Java - Statement while Statement

What is while loop?

A while statement is a loop statement.

It executes a statement repeatedly as long as a condition is true.

Syntax

The general form of a while-loop statement is

while (condition-expression)
        Statement

The condition-expression must be a boolean expression.

The statement can be a simple statement or a block statement.

• The condition-expression is evaluated first.
• If it returns true, the statement is executed.
• Then, the condition-expression is evaluated.
• If it returns true, the statement is executed.
• It loops until the condition-expression returns false.

The condition-expression in a while-loop statement is not optional.

The body of a while loop may not be executed even once if the condition-expression evaluates to false for the first time.

To make a while statement infinite loop, use the boolean literal true as the condition-expression.

while (true)
   System.out.println ("This is an infinite loop");

Some for-loop statements can be converted to a while-loop statement.

The conversion between a for-loop and a while-loop statement is shown below.

A for-loop statement:

for (initialization; condition-expression; expression-list)
      Statement

Equivalent while-loop Statements:

Initialization
while (condition-expression) {
        Statement
        Expression-list
}

Related Topics

• Use break statement to exit a while-loop
• Input Validation with while loop
• Sum integer till a value using while loop
• find the average of any amount of numbers using while loop
• Sum all values using while loop
• Compare while loop and for loop

Example

• Print all integers between 1 and 10 using a while-loop
• Write code to Counts how many times the substring appears in the larger string.
• Write code to join Iterable<String> to a string using while loop
• Write code to repeat a string using while loop
• Write code to count string occur Times using while loop and String.indexOf()
• Write code to count number Of character Occurences in a string using indexOf() and while loop
• Write code to trim a string with while loop and Character.isWhitespace
• Convert byte array to hex string with do while loop
• Write code to generate Random String using while loop
• calculates average of however many test scores user enters

Exercise

• Write code to Returns the longest common prefix for two Strings or "" if no prefix is shared

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