Break And Continue ​

Whether it is a while loop or a for loop, there are two special statements that can be used, namely the break statement and the continue statement.

break ​

During the loop, you can use the break statement to jump out of the current loop. Let's look at an example:

public class Main {
  public static void main(String[] args) {
    int sum = 0;
    for (int i=1; ; i++) {
      sum = sum + i;
      if (i == 100) {
        break;
      }
    }
    System.out.println(sum);
  }
}

When using a for loop to calculate from 1 to 100, we do not set the detection condition for loop exit in for() . However, inside the loop, we use if to judge. If i==100 , we exit the loop through break .

Therefore, the break statement is usually used in conjunction with the if statement. Pay special attention to the fact that the break statement always jumps out of the loop at which it is located. For example:

public class Main {
    public static void main(String[] args) {
        for (int i=1; i<=10; i++) {
            System.out.println("i = " + i);
            for (int j=1; j<=10; j++) {
                System.out.println("j = " + j);
                if (j >= i) {
                    break;
                }
            }
            // jump here
            System.out.println("breaked");
        }
    }
}

The above code is two for loops nested. Because the break statement is located in the inner for loop, it will break out of the inner for loop, but not the outer for loop.

continue ​

break will jump out of the current loop, that is, the entire loop will not be executed. continue ends this loop early and continues directly to the next loop. Let's look at an example:

public class Main {
    public static void main(String[] args) {
        int sum = 0;
        for (int i=1; i<=10; i++) {
            System.out.println("begin i = " + i);
            if (i % 2 == 0) {
                continue; // This cycle will end
            }
            sum = sum + i;
            System.out.println("end i = " + i);
        }
        System.out.println(sum); // 25
    }
}

Pay attention to the effect of the continue statement. When i is an odd number, the entire loop is executed completely, so begin i=1 and end i=1 are printed. When i is an even number, the continue statement will end this loop early. Therefore, begin i=2 will be printed but end i=2 will not be printed.

In multi-level nested loops, the continue statement also ends the current loop.

Summary ​

The break statement can jump out of the current loop;

The break statement is usually used with if to end the entire loop early when the condition is met;

The break statement always jumps out of the nearest loop;

The continue statement can end this loop early;

The continue statement is usually used with if to end the loop early when the conditions are met.