break和continue标签的用法

Java中for循环中执行顺序问题及break, continue标签用法

博客分类：

• Java综合

 

public class labeledfor {
  static test monitor = new test();
  public static void main(string[] args) {
      int i = 0;
      outer: // can't have statements here
      for(; true ;) { // infinite loop
           inner: // can't have statements here
           for(; i < 10; i++) {
                system.out.println("i = " + i);
                if(i == 2) {
                    system.out.println("continue");
                    continue;
                }
                if(i == 3) {
                    system.out.println("break");
                    i++; // otherwise i never
                          // gets incremented.
                    break;
                }
                if(i == 7) {
                    system.out.println("continue outer");
                    i++; // otherwise i never
                           // gets incremented.
                    continue outer;
                }
                if(i == 8) {
                    system.out.println("break outer");
                    break outer;
                }

                for(int k = 0; k < 5; k++) {
                    if(k == 3) {
                         system.out.println("continue inner");
                         continue inner;
                    }

public class labeledfor {
  static test monitor = new test();
  public static void main(string[] args) {
      int i = 0;
      outer: // can't have statements here
      for(; true ;) { // infinite loop
           inner: // can't have statements here
           for(; i < 10; i++) {
                system.out.println("i = " + i);
                if(i == 2) {
                    system.out.println("continue");
                    continue;
                }
                if(i == 3) {
                    system.out.println("break");
                    i++; // otherwise i never
                          // gets incremented.
                    break;
                }
                if(i == 7) {
                    system.out.println("continue outer");
                    i++; // otherwise i never
                           // gets incremented.
                    continue outer;
                }
                if(i == 8) {
                    system.out.println("break outer");
                    break outer;
                }

                for(int k = 0; k < 5; k++) {
                    if(k == 3) {
                         system.out.println("continue inner");
                         continue inner;
                    }

 结果:
"i = 0",
"continue inner",
"i = 1",
"continue inner",
"i = 2",
"continue",
"i = 3",
"break",
"i = 4",
"continue inner",
"i = 5",
"continue inner",
"i = 6",
"continue inner",
"i = 7",
"continue outer",
"i = 8",
"break outer"

总结：

  (1):一般的continue会退回最内层循环的开头（顶部），并继续执行。
  (2):带标签的continue会到达标签的位置，并重新进入紧接在那个标签后面的循环。
  (3):一般的break会中断并跳出当前的循环。
  (4):带标签的break会中断并跳出标签所指的循环。
要记住的重点是：在Java里面需要使用标签的唯一理由是因为有循环嵌套的存在，而且想从多层嵌套中break或continue。