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In computer programming, loops are used to repeat a block of code. For example, if you want to show a message 100 times, then you can use a loop. It's just a simple example; you can achieve much more with loops.

In the previous tutorial, you learned about Java for loop . Here, you are going to learn about while and do...while loops.

Java while loop

Java while loop is used to run a specific code until a certain condition is met. The syntax of the while loop is:

• A while loop evaluates the textExpression inside the parenthesis () .
• If the textExpression evaluates to true , the code inside the while loop is executed.
• The textExpression is evaluated again.
• This process continues until the textExpression is false .
• When the textExpression evaluates to false , the loop stops.

To learn more about the conditions, visit Java relational and logical operators .

Flowchart of while loop

Example 1: Display Numbers from 1 to 5

Here is how this program works.

Example 2: Sum of Positive Numbers Only

In the above program, we have used the Scanner class to take input from the user. Here, nextInt() takes integer input from the user.

The while loop continues until the user enters a negative number. During each iteration, the number entered by the user is added to the sum variable.

When the user enters a negative number, the loop terminates. Finally, the total sum is displayed.

Java do...while loop

The do...while loop is similar to while loop. However, the body of do...while loop is executed once before the test expression is checked. For example,

• The body of the loop is executed at first. Then the textExpression is evaluated.
• If the textExpression evaluates to true , the body of the loop inside the do statement is executed again.
• The textExpression is evaluated once again.
• This process continues until the textExpression evaluates to false . Then the loop stops.

Flowchart of do...while loop

Let's see the working of do...while loop.

Example 3: Display Numbers from 1 to 5

Example 4: Sum of Positive Numbers

Here, the user enters a positive number, that number is added to the sum variable. And this process continues until the number is negative. When the number is negative, the loop terminates and displays the sum without adding the negative number.

Here, the user enters a negative number. The test condition will be false but the code inside of the loop executes once.

Infinite while loop

If the condition of a loop is always true , the loop runs for infinite times (until the memory is full). For example,

Here is an example of an infinite do...while loop.

In the above programs, the textExpression is always true . Hence, the loop body will run for infinite times.

for and while loops

The for loop is used when the number of iterations is known. For example,

And while and do...while loops are generally used when the number of iterations is unknown. For example,

Table of Contents

• Introduction
• Java while Loop
• Flowchart of while Loop
• Example: while Loop
• Java do...while Loop
• Flowchart of do...while Loop
• Example: do...while Loop
• Infinite while Loop
• Java for vs while loop

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The Java while Loop

The java do while loop, the continue command, the break command, variable visibility in while loops, while loops in other languages.

The Java while loop is similar to the for loop . The while loop enables your Java program to repeat a set of operations while a certain conditions is true.

The Java while loop exist in two variations. The commonly used while loop and the less often do while version. I will cover both while loop versions in this text.

Let us first look at the most commonly used variation of the Java while loop. Here is a simple Java while loop example:

This example shows a while loop that executes the body of the loop as long as the counter variable is less than 10. Inside the while loop body the counter is incremented. Eventually the counter variable will no longer be less than 10, and the while loop will stop executing.

Here is another while example that uses a boolean to make the comparison:

This Java while example tests the boolean variable shouldContinue to check if the while loop should be executed or not. If the shouldContinue variable has the value true , the while loop body is executed one more time. If the shouldContinue variable has the value false , the while loop stops, and execution continues at the next statement after the while loop.

Inside the while loop body a random number between 0 and 10 is generated. If the random number is larger than 5, then the shouldContinue variable will be set to true . If the random number is 5 or less, the shouldContinue variable will be set to false .

Like with for loops, the curly braces are optional around the while loop body. If you omit the curly braces then the while loop body will consist of only the first following Java statement. Here is a Java while example illustrating that:

In this example, only the first System.out.println() statement is executed inside the while loop. The second System.out.println() statement is not executed until after the while loop is finished.

Forgetting the curly braces around the while loop body is a common mistake. Therefore it can be a good habit to just always put them around the while loop body.

The second variation of the Java while loop is the do while construct. Here is a Java do while example:

Notice the while loop condition is now moved to after the do while loop body. The do while loop body is always executed at least once, and is then executed repeatedly while the while loop condition is true .

The main difference between the two while loop variations is exactly that the do while loop is always executed at least once before the while loop condition is tested. This is not the case with the normal while loop variation explained in the beginning of this text.

The two variations of the Java while loop come in handy in different situations. I mostly used the first while loop variation, but there are situations where I have used the second variation.

Java contains a continue command which can be used inside Java while (and for ) loops. The continue command is placed inside the body of the while loop. When the continue command is met, the Java Virtual Machine jumps to the next iteration of the loop without executing more of the while loop body. The next iteration of the while loop body will proceed as any other. If that iteration also meets the continue command, that iteration too will skip to the next iteration, and so forth.

Here is a simple continue example inside a while loop:

Notice the if statement inside the while loop. This if statement checks if each String in the strings array does not start with with the letter j . If not, then the continue command is executed, and the while loop continues to the next iteration.

If the current String in the strings array does start with the letter j , then the next Java statement after the if statement is executed, and the variable wordsStartingWithJ is incremented by 1.

The continue command also works inside do while loops. Here is a do while version of the previous example:

Notice that this version of the while loop requires that the strings array has a least one element, or it will fail when trying to index into the array at position 0 during the first iteration of the do while loop.

The break command is a command that works inside Java while (and for ) loops. When the break command is met, the Java Virtual Machine breaks out of the while loop, even if the loop condition is still true. No more iterations of the while loop are executed once a break command is met. Here is a break command example inside a while loop:

Notice the second if statement inside the while loop. This if statement checks if 3 words or more have been found which starts with the letter j . If yes, the break command is executed, and the program breaks out of the while loop.

Like with the continue command, the break command also works inside do while loops. Here is the example from before, using a do while loop instead:

Note that this variation of the while loop requires that the strings array always has at least one element. If not, it will fail during the first iteration of the do while loop, when it tries to access the first element (with index 0) of the array.

Variables declared inside a Java while loop are only visible inside the while loop body. Look at this while loop example:

After the while loop body has finished executing the count variable is still visible, since the count variable is declared outside the while loop body. But the name variable is not visible because it is declared inside the while loop body. Therefore the name variable is only visible inside the while loop body.

For the curious reader, here are links to tutorials about while loop instructions in all the programming languages covered here at Jenkov.com :

• while in Java
• while in Python

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Is doing an assignment inside a condition considered a code smell?

Many times I have to write a loop that requires initialization of a loop condition, and an update every time the loop executes. Here's one example:

One things I dislike about this code is the duplicate call to getCurrentStrings() . One option is to add the assignment to the condition as follows:

But while I now have less duplication and less code, i feel that my code is now harder to read. On the other hand, it is easier to understand that we are looping on a variable that may be changed by the loop.

What is the best practice to follow in cases like this?

• 5 Doing a call like GetCurrentStrings() once outside a while loop, and then calling it inside the loop, is a very common, well understood, accepted as best practice pattern. It's not code duplication; you have to call GetCurrentStrings() once outside the loop to establish the initial condition for the while . –  Robert Harvey Commented Mar 20, 2014 at 15:57

5 Answers 5

First, I would definitely frame the first version as a for-loop:

Unfortunately there's no idiomatic way in C++, Java or C# that I know of to get rid of the duplication between initializer and incrementer. I personally like abstracting the looping pattern into an Iterable or Enumerable or whatever your language provides. But in the end, that just moves the duplication into a reusable place. Here's a C# example:

Now you can do this:

C#'s yield makes writing this easy; it's uglier in Java or C++.

C++ culture is more accepting of assignment-in-condition than the other languages, and implicit boolean conversions are actually used in some idioms, e.g. type queries:

The above relies on the implicit conversion of pointers to bool and is idiomatic. Here's another:

This modifies the variable s within the condition.

The common pattern, however, is that the condition itself is trivial, usually relying completely on some implicit conversion to bool. Since collections don't do that, putting an empty test there would be considered less idiomatic.

C culture is even more accepting, with the fgetc loop idiom looking like this:

But in higher-level languages, this is frowned upon, because with the higher level usually comes lesser acceptance of tricky code.

• Liked the multiple explanations and examples. Thanks! –  vainolo Commented Mar 24, 2014 at 8:28

The fundamental problem here, it seems to me, is that you have a N plus one half loop , and those are always a bit messy to express. In this particular case, you could hoist the "half" part of the loop into the test, as you have done, but it looks very awkward to me. Two ways of expressing that loop may be:

Idiomatic C/C++ in my opinion:

Strict "structured programming", which tends to frown on break :

• Indeed, for(;;) is a dead giveaway, that there's a break (or return) inside the loop. When not abused, it can make for a very clear yet concise loop construct. –  hyde Commented Mar 20, 2014 at 16:12

The former code seems more rational and readable to me and the whole loop also makes perfect sense. I'm not sure about the context of the program, but there is nothing wrong with the loop structure in essence.

The later example seems trying to write a Clever code, that is absolutely confusing to me in the first glance.

I also agree with Rob Y 's answer that in the very first glance you might think it should be an equation == rather than an assignment , however if you actually read the while statement to the end you will realize it's not a typo or mistake, however the problem is that you can't clearly understand Why there is an assignment within the while statement unless you keep the function name exactly same as doThingsThatCanAlterCurrentStrings or add an inline comment that explains the following function is likely to change the value of currentStrings .

That sort of construction shows up when doing some sort of buffered read, where the read fills a buffer and returns the number of bytes read, or 0. It's a pretty familiar construct.

There's a risk someone might think you got = confused with == . You might get a warning if you're using a style checker.

Honestly, I'd be more bothered by the (...).size() than the assignment. That seems a little iffy, because you're dereferencing the assignment. ;)

I don't think there's a hard rule, unless you're strictly following the advice of a style checker & it flags it with a warning.

Duplication is like medicine. It's harmful in high doses, but can be beneficial when appropriately used in low doses. This situation is one of the helpful cases, as you've already refactored out the worst duplication into the getCurrentStrings() function. I agree with Sebastian, though, that it's better written as a for loop.

Along those same lines, if this pattern is coming up all the time, it might be a sign that you need to create better abstractions, or rearrange responsibilities between different classes or functions. What makes loops like these problematic is they rely heavily on side effects. In certain domains that's not always avoidable, like I/O for example, but you should still try to push side effect-dependent functions as deep into your abstraction layers as possible, so there aren't very many of them.

In your example code, without knowing the context, the first thing I would do is try to find a way to refactor it to do all the work on my local copy of currentStrings , then update the external state all at once. Something like:

If the current strings are being updated by another thread, an event model is often in order:

You get the picture. There's usually some way to refactor your code to not depend on side effects as much. If that's not practical, you can often avoid duplication by moving some responsibility to another class, as in:

It might seem like overkill to create a whole new CurrentStrings class for something that can be mostly served by a List<String> , but it will often open up a whole gamut of simplifications throughout your code. Not to mention the encapsulation and type-checking benefits.

• 2 Why would you ever write something as a for loop when you don't know ahead of time how many iterations you're going to have? That's what while is for. –  Robert Harvey Commented Mar 20, 2014 at 16:01
• That's a whole question in itself, but for loops have a defined initial condition, stop condition, update, and body. Usually when those four elements exist and are not overly complex, it's preferable to use a for loop. For one thing, it limits the scope of loop variables to the loop body itself. For another, it provides an unambiguous place to look for those elements, which is a big readability boost in a large loop. Loops with fixed iteration counts happen to fit the for loop criteria, but that doesn't mean they're the only kind of loops that do. –  Karl Bielefeldt Commented Mar 20, 2014 at 16:30
• Well, if I were using a loop variable (that increments or decrements in each loop iteration), I wouldn't use a while anyway. That's not the case in the OP. –  Robert Harvey Commented Mar 20, 2014 at 16:32
• Sure it is. currentStrings is a loop variable. It changes on every iteration and is the basis for the stop condition. It doesn't have to be a counter. –  Karl Bielefeldt Commented Mar 20, 2014 at 16:36
• Yeah, thought I qualified my use of the term "loop variable" in my last comment. Oh, well. –  Robert Harvey Commented Mar 20, 2014 at 16:37

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Java while loop – tutorial & examples.

in Java Tutorials June 4, 2024 Comments Off on Java While Loop – Tutorial & Examples

While Loop In Java – Executing a set of statements repeatedly is known as looping. We have 3 types of looping constructs in Java. These looping statements are also known as iterative statements.

All the three are used primarily with same purpose and the difference is in their syntax. Because of the syntactical differences, their behavior may differ a little bit. We will see the differences soon. More than the behavior it is programmer’s choice about what looping constructor to use when.

Example For While Loop – While Loop Basics

Definition Of While Loop

This loop is used to execute a set of statements repeatedly as long as a condition is true.

When control comes to this loop, the condition in the header is evaluated to check whether it results in true or false. If the condition is true, the control enters the loop body and executes the statements in it.

After executing the statements, the control automatically comes up to the condition part and checks whether the condition results in true (the code in body might have changed value of some variable so that the conditions truth value may change).

If the condition results in true, then control enters the body again to execute the statements in it. Then the control goes to condition part again.

This process is continued as long as the condition results in true . When the condition results in false, the control goes to the statement immediately following the loop.

Example Program for Java While Loop:

Execution Order:

Another Example Program For While Loop In Java:

In the above example, by the time control comes to header part of the loop, a is 1 and b is 3 so the condition a<=b results in true.

So the control comes into loop body and prints “mouse” . Then value of a is incremented by 1 so it becomes 2. Then the control comes-up to the condition part automatically and checks its truth value.

As value of a is 2 now, the condition results in true again. So the body executes and prints “mouse” again. Then a becomes 3.

Then the control comes to condition part again which results in true. So the loop body is executed third time to print “mouse” and to increment a by 1 .

This time a is 4 so the condition results in false (4<=3) . As the condition is false, the control comes to the statement after the loop and prints “cat”.

Loop Control Variables

The truth value of the condition depends on one or more variables. Such variables are known as loop control variables.

In the above example, the condition in loop header depends on the variable a and b. A change in any of these two variables will affect the truth value of the condition. In this particular example, value of b is not changed at all in the loop. So a is the primary loop control variable here.

Body With Single Statement

Similar to if/else block, the while loop block also do not need curly braces when there is only one statement. So the following two examples will give same effect.

Generally the loop body is executed N number of times and the condition is checked for N+1 number of times. For the first N times, the condition results in true and the (N+1)th time the condition results in false.

Infinite Loops

Sometimes we write a looping construct as if the condition results in true always. Such loops are known as infinite loops or indefinite loops.

Example Program For Infinite Loop:

This kind of loops are used when we don’t know exactly when to come out of the loop. At middle of the loop body, we may need to come out depending on a resultant value after an expression is evaluated or a user entered value met a condition. When such a situation arises we can come out using a statement like ‘break ’ or ‘return’.

Executing Part Of The Body In An Iteration

If we want to skip remaining statements of a loop in the current iteration (round), then we can use ‘continue’ statement at middle of a loop body. Then the control automatically goes to the next iteration (condition part). The next time (in the next iteration) all the statements of the loop body may get executed.

Only Boolean Values Are Accepted

The condition in the header should always result in a Boolean value (true or false). No other value is allowed (similar to condition in if header).

Nested Loops

We can have a looping construct inside another looping construct. This kind of arrangement is known as nested looping.

There is no limit on depth of nesting.  We can have any other loop inside a while loop. In fact any loop can have any other loop as part of its nesting. Not only a loop, any other construct (if, switch, etc) can be placed in a loop.

Initialization, Condition and Incrementation

Generally a loop execution depends on initial value of loop control variable, condition of loop and incrementation/decrementation of loop control variable.

The following loop executes for 10 times.

Dummy Statement As Loop Body

If we put a semi-colon at the end of a while expression, that semi-colon becomes body of the loop. In that case anything after the semi-colon becomes out of the loop.

In the above example we have 3 statements. int a=10; is before the loop and System.out.println(a); is after the loop.

The loop statement ends in its line itself. The semi-colon in the line (2nd line) is body of the loop. So as long as the condition (a++ < 13) is true the dummy statement (semi-colon) is executed.

When condition results in false , the control comes out to print a value. So the printing statement is executed only once with that code. When it is printed, it prints 14.

Hope you like this tutorial, In case if you have any doubts do leave a comment here.

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The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available. See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases. See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.

Assignment, Arithmetic, and Unary Operators

The simple assignment operator.

One of the most common operators that you'll encounter is the simple assignment operator " = ". You saw this operator in the Bicycle class; it assigns the value on its right to the operand on its left:

This operator can also be used on objects to assign object references , as discussed in Creating Objects .

The Arithmetic Operators

The Java programming language provides operators that perform addition, subtraction, multiplication, and division. There's a good chance you'll recognize them by their counterparts in basic mathematics. The only symbol that might look new to you is " % ", which divides one operand by another and returns the remainder as its result.

The following program, ArithmeticDemo , tests the arithmetic operators.

This program prints the following:

You can also combine the arithmetic operators with the simple assignment operator to create compound assignments . For example, x+=1; and x=x+1; both increment the value of x by 1.

The + operator can also be used for concatenating (joining) two strings together, as shown in the following ConcatDemo program:

By the end of this program, the variable thirdString contains "This is a concatenated string.", which gets printed to standard output.

The Unary Operators

The unary operators require only one operand; they perform various operations such as incrementing/decrementing a value by one, negating an expression, or inverting the value of a boolean.

The following program, UnaryDemo , tests the unary operators:

The increment/decrement operators can be applied before (prefix) or after (postfix) the operand. The code result++; and ++result; will both end in result being incremented by one. The only difference is that the prefix version ( ++result ) evaluates to the incremented value, whereas the postfix version ( result++ ) evaluates to the original value. If you are just performing a simple increment/decrement, it doesn't really matter which version you choose. But if you use this operator in part of a larger expression, the one that you choose may make a significant difference.

The following program, PrePostDemo , illustrates the prefix/postfix unary increment operator:

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Assignment Operator in Java with Example

Assignment operator is one of the simplest and most used operator in java programming language. As the name itself suggests, the assignment operator is used to assign value inside a variable. In java we can divide assignment operator in two types :

• Assignment operator or simple assignment operator
• Compound assignment operators

What is assignment operator in java

The = operator in java is known as assignment or simple assignment operator. It assigns the value on its right side to the operand(variable) on its left side. For example :

The left-hand side of an assignment operator must be a variable while the right side of it should be a value which can be in the form of a constant value, a variable name, an expression, a method call returning a compatible value or a combination of these.

The value at right side of assignment operator must be compatible with the data type of left side variable, otherwise compiler will throw compilation error. Following are incorrect assignment :

Another important thing about assignment operator is that, it is evaluated from right to left . If there is an expression at right side of assignment operator, it is evaluated first then the resulted value is assigned in left side variable.

Here in statement int x = a + b + c; the expression a + b + c is evaluated first, then the resulted value( 60 ) is assigned into x . Similarly in statement a = b = c , first the value of c which is 30 is assigned into b and then the value of b which is now 30 is assigned into a .

The variable at left side of an assignment operator can also be a non-primitive variable. For example if we have a class MyFirstProgram , we can assign object of MyFirstProgram class using = operator in MyFirstProgram type variable.

Is == an assignment operator ?

No , it's not an assignment operator, it's a relational operator used to compare two values.

Is assignment operator a binary operator

Yes , as it requires two operands.

Assignment operator program in Java

a = 2 b = 2 c = 4 d = 4 e = false

Java compound assignment operators

The assignment operator can be mixed or compound with other operators like addition, subtraction, multiplication etc. We call such assignment operators as compound assignment operator. For example :

Here the statement a += 10; is the short version of a = a + 10; the operator += is basically addition compound assignment operator. Similarly b *= 5; is short version of b = b * 5; the operator *= is multiplication compound assignment operator. The compound assignment can be in more complex form as well, like below :

List of all assignment operators in Java

The table below shows the list of all possible assignment(simple and compound) operators in java. Consider a is an integer variable for this table.

How many assignment operators are there in Java ?

Including simple and compound assignment we have total 12 assignment operators in java as given in above table.

What is shorthand operator in Java ?

Shorthand operators are nothing new they are just a shorter way to write something that is already available in java language. For example the code a += 5 is shorter way to write a = a + 5 , so += is a shorthand operator. In java all the compound assignment operator(given above) and the increment/decrement operators are basically shorthand operators.

Compound assignment operator program in Java

a = 20 b = 80 c = 30 s = 64 s2 = 110 b2 = 15

What is the difference between += and =+ in Java?

An expression a += 1 will result as a = a + 1 while the expression a =+ 1 will result as a = +1 . The correct compound statement is += , not =+ , so do not use the later one.

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Brewers lefty DL Hall just can't catch a break while on his injury rehab assignment

DL Hall ’s rehab assignment that just won’t end takes another turn.

Hall, in what what was supposed to his final outing before rejoining the Milwaukee Brewers , took a line drive off his left forearm Wednesday night while pitching with Class AAA Nashville.

“They’re going to shut him down a little bit to make sure can get some strength back,” Brewers manager Pat Murphy said Thursday.

Hall avoided a fracture but is dealing with some bruising, so the Brewers will give him anywhere between an expected three to 10 days to regain strength and regular movement.

It’s just the latest unlucky setback in a year full of them for the left-hander.

Hall has been on the injured list with a left knee strain since April 21. He rehabbed the injury and began a rehab assignment relatively quickly on May 19 at Class High-A Wisconsin.

Almost eight weeks later, Hall is still on that same rehab assignment, though it has had to be reset twice now.

Four days after Hall began the rehab assignment, he caught a cleat going down the mound and aggravated the existing knee injury. That prompted a series of examinations with various doctors, a sequence that resulted in differing opinions. Hall ultimately opted to try to rehab the injury rather than undergo surgery.

Hall began to build up from scratch again with Nashville with an outing on June 13 and had an ERA of 1.93 through five games, at which point he was deemed one outing away from being ready.

Then, on July 4 in Memphis, a rain delay in the fourth inning prevented Hall from getting the necessary work in, so he was scheduled for one more rehab outing Wednesday.

In the third inning, Hall took a smash right off his throwing arm and exited the game.

The Brewers won’t need to build Hall back up upon his return, so he likely won’t require more than one start for Nashville upon returning.

When the time comes to take the mound again, Hall might want to carry a rabbit’s foot on to the mound for that game.

Joey Ortiz nearing a return

Third baseman Joey Ortiz was a full-go in workouts before the game Thursday and could begin a rehab assignment with Wisconsin on Friday if all goes well, Murphy said.

Ortiz has been on the IL with neck inflammation on July 3 after he had only played two of the previous six games.

In his stead, the Brewers have gotten minimal production at the hot corner from Andruw Monasterio and Vinny Capra .

This article originally appeared on Milwaukee Journal Sentinel: DL Hall injury: Brewers lefty suffers another unlucky setback on rehab

Dominic Fletcher's incredible catch

White Sox outfielder Dominic Fletcher makes an incredible catch at the wall to take away extra bases while on rehab assignment with Triple-A

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Loops in Java come into use when we need to repeatedly execute a block of statements.  Java do-while loop is an Exit control loop . Therefore, unlike for or while loop, a do-while check for the condition after executing the statements of the loop body.

Syntax:  

Note: The test_expression for the do-while loop must return a boolean value , else we would get compile-time error.

Application of do-while : Its example application is showing some kind of menu to the users. 

For example: 

You are implementing a game where you show some options to the user, press 1 to do this .., press 2 to do this .. etc and press ‘Q’ to quit the game. So here you want to show the game menu to the user at least once, so you write the code for the game menu inside the do-while loop.

Illustration:

Output explanation:

In the above code, we figured out that the condition is checked later as the body inside do will get executed one time without fail as the condition is checked later onwards. Hence whenever we want to display the menu and later on proceed command on the terminal, we always use do-while loop.

Components of do-while Loop  

A. Test Expression: In this expression, we have to test the condition. If the condition evaluates to true then we will execute the body of the loop and go to update expression. Otherwise, we will exit from the while loop. For example: 

B. Update Expression : After executing the loop body, this expression increments/decrements the loop variable by some value. For example:  

Execution of do-While loop 

• Control falls into the do-while loop.
• The statements inside the body of the loop get executed.
• Updation takes place.
• The flow jumps to Condition
• If Condition yields true, go to Step 6.
• If Condition yields false, the flow goes outside the loop
• The flow goes back to Step 2.

Flowchart do-while loop:

Implementation:

Example 1: This program will try to print “Hello World” 5 times.  

Auxiliary Space: O(1)

Output explanation:  

The program will execute in the following manner as follows:

• Program starts.
• i is initialized with value 1.
• “Hello World” gets printed 1st time.
• Updation is done. Now i = 2.
• Condition is checked. 2 < 6 yields true.
• “Hello World” gets printed 2nd time.
• Updation is done. Now i = 3.
• Condition is checked. 3 < 6 yields true.
• “Hello World” gets printed 3rd time
• Updation is done. Now i = 4.
• Condition is checked. 4 < 6 yields true.
• “Hello World” gets printed 4th time
• Updation is done. Now i = 5.
• Condition is checked. 5 < 6 yields true.
• “Hello World” gets printed 5th time
• Updation is done. Now i = 6.
• Condition is checked. 6 < 6 yields false.
• The flow goes outside the loop.

Example 3: do-while loop without curly braces {}

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Related Articles:  

• Java For loop with Examples
• Difference between while and do-while loop in C, C++, Java
• Difference between for and do-while loop in C, C++, Java

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Former Twins slugger Miguel Sano designated for assignment by Angels

Jonathan harrison | jul 8, 2024.

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The Los Angeles Angels have designated former Twins slugger Miguel Sano for assignment. The move clears room for Anthony Rendon to return the lineup after a stint on the 60-day injured list.

Sano, 31, made his return to the majors after missing the 2023 season. Signing a minor league deal in January, Sano clubbed four home runs in spring training and earned a spot on the Angels' Opening Day Roster.

A knee injury sent Sano to the injured list for nearly two months. Since returning from the injured list on June 25, he has only appeared in seven games, recording one hit in that span. Sano is slashing .205/.295/313 with just two homers so far this season.

Los Angeles now has five days to trade Sano or put him on waivers. He is unlikely to draw trade interest and could be released if he declines an assignment to the minors.

JONATHAN HARRISON

Java Tutorial

Java methods, java classes, java file handling, java how to's, java reference, java examples, java do/while loop, the do/while loop.

The do/while loop is a variant of the while loop. This loop will execute the code block once, before checking if the condition is true, then it will repeat the loop as long as the condition is true.

The example below uses a do/while loop. The loop will always be executed at least once, even if the condition is false, because the code block is executed before the condition is tested:

Try it Yourself »

Do not forget to increase the variable used in the condition, otherwise the loop will never end!

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Dozens of houses damaged after quake in Central Java

While no deaths were reported, 13 people were injured in the incident.

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total of 240 houses were damaged after a magnitude 4.4 earthquake hit Batang regency and Pekalongan city in Central Java on Sunday. While no deaths were reported, 13 people were injured in the incident.

The Batang regency administration has declared a seven-day emergency response period following the disaster.

The quake also caused damage to eight administrative office buildings, 15 schools, five houses of worship and a traditional market.

On Monday, disaster response workers cleared debris from damaged buildings in three districts. On Tuesday, activities were focused on food and non-food aid distribution to affected residents, as well as health services.

In April, a magnitude-6.5 earthquake struck off the southwestern coast of Java Island with the epicenter located about 150 kilometers away from Garut, West Java.

At least four people in the regency were injured and some buildings were damaged. The quake was felt in the capital Jakarta, where people were forced to evacuate buildings, as well as in Bandung, West Java.

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Java do while Guessing Game

So for an assignment I had to do last week I had to make a guessing game in Java using 4 do-while loops and if statements. I was unable to complete it successfully and the class has moved on providing me no help. I would appreciate it if someone could look at my code and tell me where I could improve it so the program works properly.

To give a brief description of the assignment, the assignment calls for 4 do-while loops:

• The primary do-while loop which contains most of the code and keeps the program running until the user wants to quit
• The game do-while loop which keeps the game running until the user guesses the correct number, at which point it will exit. (This part I could not figure out).
• A numeric input validation do-while loop inside of the game loop, which makes sure the user's guess is valid.
• A non-numeric input validation do-while loop which is after and outside of the game loop that asks the user if they want to play again, and checks for a valid 'Y' or 'N' response

Here is what I came up with:

I appreciate the help!

3 Answers 3

This is a working code

But, I suggest using more functions (especially for the inner for loops) to keep your code managable and more understandable.

Your problem is in this part of the program

So just use two separate booleans like so

Just as an info (not directly related to your question), be careful comparing Integers with "==", it only works for values from -128 up to 127. (but you can use == for primitive type "int")

https://wiki.owasp.org/index.php/Java_gotchas#Immutable_Objects_.2F_Wrapper_Class_Caching

You don't need two Scanner objects. You can do the entire application with a single Scanner object:

Your variables guesses , randNum , and valid should be initialized within the main game loop. This way, when a new game starts, a new random value ( randNum ) is acquired, valid is reset to boolean false, and guesses is reset to 0 .

The valid = true; located within the if (num1.hasNextInt()){ ... } IF code block of the Please enter your guess: prompt loop should be removed (deleted). This is to soon to say the input is valid and allows the prompt loop to exit. This flag should only fall true if a correct value which matches the generated randNum value is supplied by the User.

Your IF statements for checking User input should be contained within the Please enter your guess: prompt loop. This allows the indicators Too High or Too Low to be displayed and the Please enter your guess: prompt to be re-displayed for another guess.

The guesses variable is keeping an incorrect count (not enough). You only need one guesses++; and it should be placed directly after the User entry validity check IF/ELSE blocks.

You should set valid to false before entering the Do you want to play again? prompt loop.

In your Do you want to play again? prompt loop you set valid to true if either Y or N is supplied. So the main game loop is never passed through again. Because you are using the valid boolean variable as a condition for all your loops you will want to ensure that if Y (yes) is supplied then valid meets the condition required to re-loop the main game loop (which happens to be boolean false) or use a different boolean flag for this main game loop (perhaps: boolean playAgain = false; ). Currently, if Y is supplied then valid should equal false and a break; ought to be issued so as to exit the prompt loop. Because valid is false the main game loop iterates again for a new game. If N is supplied then simply exit the game at this point. There is no need to just exit the prompt loop:

Placing the:

within a do/while loop is pointless. Keep the output to console but remove the do { and } while(!valid); .

Alternative code might look something like:

To Do: Allow the User to Quit at any time.

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