将字符串作为开关盒

Question

在 switch 情况下存在错误 -> RUNNING、ABORTED 和 READY 无法解析为变量。我该怎么做才能让它发挥作用？尝试了枚举，但它确实不起作用。

我无法编辑的主类：

public class Main {
public static void main(String[] args) throws InterruptedException {
StringTask task = new StringTask("A", 70000);
System.out.println("Task " + task.getState());
task.start();
if (args.length > 0 && args[0].equals("abort")) { 

/*<- code that interrupts task after 1 sec and start a new thread
*/
}
while (!task.isDone()) {
  Thread.sleep(500);
  switch(task.getState()) {
  //error  case RUNNING: System.out.print("R."); break;
  //error  case ABORTED: System.out.println(" ... aborted."); break;
  //error  case READY: System.out.println(" ... ready."); break;
    default: System.out.println("unknown state");
  }

}
System.out.println("Task " + task.getState());
System.out.println(task.getResult().length());
}
}

StringTask 类：

public class StringTask implements Runnable {
String string;
String result = "";
String status = "";
int x;
boolean end = false;
boolean done = false;

public StringTask(String string, int x) {
    this.string = string;
    this.x = x;
    this.status = "CREATED";

}

public void start() {
    Thread thread = new Thread(this);
    thread.start();
}

public void run() {
    this.status = "RUNNING";
    synchronized (this.result) {
        try {
            for (int i = 0; i < x; i++) {
                result += string;
            }
            this.status = "READY";
            this.done = true;
        } catch (Exception ex) {
            this.status = "ABORTED";
            this.done = false;
        }
    }
}

public void abort() {
    this.end = true;
    this.done = true;
    this.status = "ABORTED";
    Thread.interrupted();
}

public StringTask() {
    this.status = "ABORTED";
}

public String getState() {
    return this.status;
}

public boolean isDone() {
    return this.done;
}

public String getResult() {
    return this.result;
}
}

Answer 1

我刚刚注意到您不能编辑主类。为了改善您的问题，您必须创建 enum 来存储状态：

public enum Status {
    RUNNING, ABORTED, READY
}

将StringTask#getState改成返回Status后，就可以使用你的switch语句了：

switch (task.getState()) {
    case RUNNING:
        System.out.print("R.");
        break;
    case ABORTED: 
        System.out.println(" ... aborted.");
        break;
    case READY:
        System.out.println(" ... ready.");
        break;
    default:
        System.out.println("unknown state");
}

Answer 2

您是否尝试在switch 的情况下使用Strings？

"RUNNING" 而不是 RUNNING 等？

Answer 3

看来您的任务是让主类与Enum 一起工作，为此您必须更改StringTask 类。将status的类型改为State

    State status;

    public StringTask(String string, int x) {
        this.string = string;
        this.x = x;
        this.status = State.CREATED;

    }
   ...

    public State getState() {
        return this.status;
    }

    ...

     enum State {
       RUNNING, ABORTED, READY
      }

那么你的开关应该可以正常工作了

  switch(task.getState()) {
    case RUNNING: 
         System.out.print("R."); 
         break;
    case ABORTED: 
         System.out.println(" ... aborted."); 
         break;
    case READY: 
         System.out.println(" ... ready."); 
         break;
    default: 
         System.out.println("unknown state");
  }