04-Jump-Statements.md

Jump Statements

Java supports three jump statements: break, continue, and return. These statements transfer control to another part of your program.

break Statement

In Java, the break statement has three uses.

• It terminates a statement sequence in a switch statement.
• It can be used to exit a loop.
• It can be used as a “civilized” form of goto.

Using break to Exit a Loop

break Statement is a loop control statement which is used to terminate the loop. As soon as the break statement is encountered from within a loop, the loop iterations stops there and control returns from the loop immediately to the first statement after the loop.

Example 01

// Using break to exit a loop.
class BreakLoop {
    public static void main(String args[]) {
        for(int i=0; i<100; i++) {
            if(i == 10) 
                break; // terminate loop if i is 10
            System.out.println("i: " + i);
        }
        System.out.println("Loop complete.");
    }
}

Output

i: 0
i: 1
i: 2
i: 3
i: 4
i: 5
i: 6
i: 7
i: 8
i: 9
Loop complete.

The break statement can be used with any of Java’s loops, including intentionally infinite loops.

When used inside a set of nested loops, the break statement will only break out of the innermost loop.

Using break as a Form of Goto

By using this form of break, you can, for example, break out of one or more blocks of code. These blocks need not be part of a loop or a switch. They can be any block. Further, you can specify precisely where execution will resume, because this form of break works with a label.

Example 02

// Using break as a civilized form of goto.
class Break {
    public static void main(String args[]) {
        boolean t = true;
        first: {
            second: {
                third: {
                    System.out.println("Before the break.");
                    if(t) 
                        break second; // break out of second block
                    System.out.println("This won't execute");
                }
                System.out.println("This won't execute");
            }
            System.out.println("This is after second block.");
        }
    }
}

Output

Before the break.
This is after second block.

Example 03

// Using break to exit from nested loops
class BreakLoop {
    public static void main(String args[]) {
        outer: for(int i=0; i<3; i++) {
            System.out.print("Pass " + i + ": ");
            for(int j=0; j<100; j++) {
                if(j == 10) 
                    break outer; // exit both loops
                System.out.print(j + " ");
            }
            System.out.println("This will not print");
        }
        System.out.println("Loops complete.");
    }
}

Output

Pass 0: 0 1 2 3 4 5 6 7 8 9 Loops complete.

continue Statement

Sometimes it is useful to force an early iteration of a loop. That is, you might want to continue running the loop but stop processing the remainder of the code in its body for this particular iteration.

The continue statement performs such an action. In while and do-while loops, a continue statement causes control to be transferred directly to the conditional expression that controls the loop. In a for loop, control goes first to the iteration portion of the for statement and then to the conditional expression.

Example 04

// Demonstrate continue.
class Continue {
    public static void main(String args[]) {
        for(int i=0; i<10; i++) {
            System.out.print(i + " ");
            if (i%2 == 0)
                continue;
            System.out.println("");
        }
    }
}

Output

0 1
2 3
4 5
6 7
8 9

As with the break statement, continue may specify a label to describe which enclosing loop to continue.

Example 05

// Using continue with a label.
class ContinueLabel {
    public static void main(String args[]) {
        outer: for (int i=0; i<10; i++) {
            for(int j=0; j<10; j++) {
                if(j > i) {
                    System.out.println();
                    continue outer;
                }
                System.out.print(" " + (i * j));
            }
        }
        System.out.println();
    }
}

Output

0
0 1
0 2 4
0 3 6 9
0 4 8 12 16
0 5 10 15 20 25
0 6 12 18 24 30 36
0 7 14 21 28 35 42 49
0 8 16 24 32 40 48 56 64
0 9 18 27 36 45 54 63 72 81

External Sources

Readings

• JavaTPoint
  • break
  • continue
• Beginners Book
  • break
  • continue
• GeeksForGeeks
  • break
  • continue