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The while and do-while Statements

Thewhile statement continually executes a block of statements while a particular condition istrue. Its syntax can be expressed as:

while (expression) {     statement(s)}

Thewhile statement evaluatesexpression, which must return aboolean value. If the expression evaluates totrue, thewhile statement executes thestatement(s) in thewhile block. Thewhile statement continues testing the expression and executing its block until the expression evaluates tofalse. Using thewhile statement to print the values from 1 through 10 can be accomplished as in the followingWhileDemo program:

class WhileDemo {    public static void main(String[] args){        int count = 1;        while (count < 11) {            System.out.println("Count is: " + count);            count++;        }    }}

You can implement an infinite loop using thewhile statement as follows:

while (true){    // your code goes here}

The Java programming language also provides ado-while statement, which can be expressed as follows:

do {     statement(s)} while (expression);

The difference betweendo-while andwhile is thatdo-while evaluates its expression at the bottom of the loop instead of the top. Therefore, the statements within thedo block are always executed at least once, as shown in the followingDoWhileDemo program:

class DoWhileDemo {    public static void main(String[] args){        int count = 1;        do {            System.out.println("Count is: " + count);            count++;        } while (count < 11);    }}