Can we call a “case” inside another case in the same switch statement in Java?

问题:

My intention is to call two cases inside another case in the same switch statement,

switch (orderType) {         case 1:              statement 1;             break;        case 2:             statement 2;             break;        case 3:              **call case 1;**              **Call case 2;**              break;        default:             break;` } 

Can we do that in Java?

回答1:

Although you cannot influence the switch cases directly, you can call switch's parent method from one case and pass different arguments. For example,

void foo(int param1, String param2, ...) {     switch (param1) {         case 0:             foo(1, "some string");             break;          case 1:             //do something             break;          default:             break;     } } 

回答2:

No, you can't jump to the code snippet in another switch case. You can however extract the code into an own method that can be called from another case:

switch (orderType) {     case 1:          someMethod1();         break;     case 2:         someMethod2();         break;     case 3:         someMethod1();         someMethod2();         break;     default:         break; }  void someMethod1() { ... } void someMethod2() { ... } 

回答3:

You can't just call a another case block like this. What you could do, though, is wrap each of these blocks in a method, and reuse them:

private void doSomething() {     // implementation }  private void doSomethingElse() {     // implementation }  private void runSwitch(int order) {      switch (orderType) {            case 1:                  doSomething();                 break;            case 2:                 doSomethingElse();                 break;            case 3:                 doSomething();                 doSomethingElse();                 break;            default:                 break;     } } 

回答4:

As others have pointed out, you can implement your switch cases inside a method which takes a parameter, which corresponds to the desired switch case. These switch cases can recursively call the same method, with the desired switch cases. Here is a fully-working example which allows you to check if a year is a leap year, or not:

public class LeapYear {      static int year = 2016;      public static void main(String[] args) {          leapSwitch(1);      }      public static void leapSwitch(int switchcase) {          switch (switchcase) {          case 1: {             if (year % 4 == 0) {                 leapSwitch(2);             } else {                 leapSwitch(5);             }         }             break;          case 2: {             if (year % 100 == 0) {                 leapSwitch(3);              } else {                 leapSwitch(4);             }         }             break;          case 3: {             if (year % 400 == 0) {                 leapSwitch(4);              } else {                 leapSwitch(5);             }         }             break;          case 4: {             System.out.println(year+ " is a leap year!");         }             break;          case 5: {             System.out.println("Not a leap year...");         }             break;          }     } } 

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