java中的"goto"--label

时间:2024-06-17 20:36:01

java中没有goto,但是goto是保留字。例如int goto;是不合法的。

但是java中有标签,仅作用在多重循环的continue和break中。

continue和break只能作用于本层循环,但是有了标签可以直接跳出多重循环。

代码举例:

public class Main {

	public static void main(String[] args) {

		first: // 标签与循环直接不可以加语句
for (int i = 0; i < 3; ++i) {
System.out.println("\nfirst: " + (i + 1) + " times start"); second:
for (int j = 0; j < 2; ++j) {
System.out.println("\tsecond: " + (j + 1) + " times start");
if (i == 1 && j == 1) {
System.out.println("\t----break----");
break;
} for (int k = 0; k < 2; ++k) {
System.out.println("\t\tthird: " + (k + 1) + " times start");
if (i == 1 && j == 0 && k == 0) {
System.out.println("\t\t----continue----");
continue;
}
if (i == 2 && j == 0) {
System.out.println("\t\t----continue second----");
continue second;
}
if (i == 2 && j == 1 && k == 1) {
System.out.println("\t\t----break first----");
break first;
} System.out.println("\t\tthird: " + (k + 1) + " times end");
}
System.out.println("\tsecond: " + (j + 1) + " times end");
}
System.out.println("first: " + (i + 1) + " times end");
} } }

输出:

first: 1 times start
second: 1 times start
third: 1 times start
third: 1 times end
third: 2 times start
third: 2 times end
second: 1 times end
second: 2 times start
third: 1 times start
third: 1 times end
third: 2 times start
third: 2 times end
second: 2 times end
first: 1 times end first: 2 times start
second: 1 times start
third: 1 times start
----continue----
third: 2 times start
third: 2 times end
second: 1 times end
second: 2 times start
----break----
first: 2 times end first: 3 times start
second: 1 times start
third: 1 times start
----continue second----
second: 2 times start
third: 1 times start
third: 1 times end
third: 2 times start
----break first----