输出如何变成2？不明白

Question

public class Ex33 {
    public static void main(String[] args) {
        int x = 3, result = 4;
        switch (x + 3) {
            case 6: result = 0;
            case 7: result = 1;
            default: result += 1;
        }
        System.out.println(result);
    }
}

不明白答案怎么变成2？

Answer 1

case 语句 "fall through" 没有 break

case 7: result = 1;   // <-- no break, so
default: result += 1; // <-- happens after case 7

这是documented行为

Another point of interest is the break statement. Each break statement terminates the enclosing switch statement. Control flow continues with the first statement following the switch block. The break statements are necessary because without them, statements in switch blocks fall through: All statements after the matching case label are executed in sequence, regardless of the expression of subsequent case labels, until a break statement is encountered

Answer 2

由于在每种情况下都缺少 break;，您的 case 语句会落空并且无法跳出循环。您所有的案例都被应用，因此导致 result = 2.

格式正确的代码如下所示：

    int x =3, result=4;

    switch (x+4){
        case 6: 
            result = 0;
            break;

        case 7: 
            result = 1;
            break;

        default: 
            result+=1;
    }

    System.out.println(result);

Answer 3

如果要停止执行其他 case 语句，则必须在每个 case 之后放置 break 语句。因此，将结果值设为 1 的等效代码是：

int x =3, result=4;
        switch (x+4){
            case 6: result = 0;
            break;
            case 7: result = 1;
            break;
            default: result+=1;
        }
        System.out.println(result);

阅读 switch 语句的一些重要规则 部分来自 here

Answer 4

匹配的case标签之后的所有语句都依次执行，不管后面的case标签的表达式如何，直到遇到break语句。进行有效的中断操作！

输出如何变成2？不明白

how does the output became 2? don't understand

java

coding-style

switch-statement