Java Tutorial/Statement Control/While Loop

Java"s "labeled while" loop

   <source lang="java">

public class MainClass {

 public static void main(String[] args) {
   int i = 0;
   outer: while (true) {
     System.out.println("Outer while loop");
     while (true) {
       i++;
       System.out.println("i = " + i);
       if (i == 1) {
         System.out.println("continue");
         continue;
       }
       if (i == 3) {
         System.out.println("continue outer");
         continue outer;
       }
       if (i == 5) {
         System.out.println("break");
         break;
       }
       if (i == 7) {
         System.out.println("break outer");
         break outer;
       }
     }
   }
 }

}</source>

Outer while loop
i = 1
continue
i = 2
i = 3
continue outer
Outer while loop
i = 4
i = 5
break
Outer while loop
i = 6
i = 7
break outer

The while Statement

1. One way to create a loop is by using the while statement.
2. Another way is to use the for statement

The while statement has the following syntax.

   <source lang="java">

while (booleanExpression) {

   statement (s)

}</source>

Using the while loop to calculate sum

   <source lang="java">

public class MainClass {

 public static void main(String[] args) {
   int limit = 20;
   int sum = 0;
   int i = 1;
   while (i <= limit) {
     sum += i++;
   }
   System.out.println("sum = " + sum);
 }

}</source>

sum = 210

While loop with double value

   <source lang="java">

public class MainClass {

 public static void main(String[] args) {
   double r = 0;
   while(r < 0.99d) {
     r = Math.random();
     System.out.println(r);
   }
 }

}</source>

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0.3867695752401421
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0.3240420706550172
0.07246065490188025
0.35761285323105796
0.9964556875646731