Exiting a Loop

The normal way to exit a loop is for the tested condition to become false. This is true of all three types of loops in Java. There might be times when you want a loop to end immediately, even if the condition being tested is still true. You can accomplish this with a break statement, as shown in the following code:

int index = 0;
while (index <= 1000) {
    index = index + 5;
    if (index == 400) {
        break;
    }
}

A break statement ends the loop that contains the statement.

In this example, the while loop loops until the index variable is greater than 1,000. However, a special case causes the loop to end earlier than that: If index equals 400, the break statement is executed, ending the loop immediately.

Another special-circumstance statement you can use inside a loop is continue. The continue statement causes the loop to exit its current trip through the loop and start over at the first statement of the loop. Consider the following loop:

int index = 0;
while (index <= 1000) {
    index = index + 5;
    if (index == 400)
        continue;
    System.out.println("The index is " + index);
}

In this loop, the statements are handled normally unless the value of index equals 400. In that case, the continue statement causes the loop to go back to the while statement instead of proceeding normally to the System.out.println() statement. Because of the continue statement, the loop never displays the following text:

The index is 400

You can use the break and continue statements with all three kinds of loops.

The break statement makes it possible to create a loop in your program that’s designed to run forever, as in this example:

while (true) {
    if (quitKeyPressed == true) {
        break;
    }
}