如何中断一个线程onBackPressed而不崩溃

Question

我已经尝试重写onBackPressed不仅完成当前活动，而且还中断线程，因为我正在调用一个意图到下一个活动内。当我按回之前，溅射活动完成，但线程继续运行，并调用下一个活动的意图。现在我已经包含了线程中断onBackPressed，当我按回应用程序崩溃。我做错了什么?

skipscreen.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            SharedPreferences savestate = getSharedPreferences("skip", MODE_PRIVATE);
            savestate.edit().putBoolean("skip", true).apply();
            skip= true;
            homeintent();
        }
    });
    Thread splashthread = new Thread() {
        @Override
        public void run() {
                try {
                    sleep(3000);
                    if (!skip) { homeintent();}
                } catch (InterruptedException Interrupt) {
                    Interrupt.printStackTrace();
                }
            }
    };
    splashthread.start();
}
private void homeintent() {
    Intent i = new Intent(splash.this, home.class);
    startActivity(i);
    finish();
}
@Override
public void onBackPressed() {
    splashthread.interrupt();
    finish();
  }
}

更新:(这个解决方案对我有效)。

skipscreen.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            SharedPreferences savestate = getSharedPreferences("skip", MODE_PRIVATE);
            savestate.edit().putBoolean("skip", true).apply();
            skip= true;
            homeintent();
        }
    });
    Thread splashthread = new Thread() {
        @Override
        public void run() {
                try {
                    sleep(3000);
                    if (!skip) { homeintent();}
                } catch (InterruptedException Interrupt) {
                    Interrupt.printStackTrace();
                }
            }
    };
    splashthread.start();
}
private void homeintent() {
    if (!ThreadInterrupted) {
           Intent i = new Intent(splash.this, home.class);
           startActivity(i);
   }
           finish();
}
@Override
public void onBackPressed() {
        SharedPreferences savestate= getSharedPreferences("ThreadInterrupted", MODE_PRIVATE);
        savestate.edit().putBoolean("ThreadInterrupted", true).apply();
        ThreadInterrupted = true;
        homeintent();
    }
}

Answer 1

为了给您一个简洁的答案，并解释将来如何做到这一点，请查看Handler类和Handler. postdelayed()方法。

 private Handler homeIntenthandler;
    @Override
    protected void onCreate(){
    //other things
        skipscreen.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                SharedPreferences savestate = getSharedPreferences("skip", MODE_PRIVATE);
                savestate.edit().putBoolean("skip", true).apply();
                skip= true;
                homeintent();
            }
        });
//initialise handler and set timer;
        homeIntenthandler= new Handler();
        homeIntenthandler.postDelayed(new Runnable() {
            @Override
            public void run() {
               homeintent();
            }
        },3000);
    }
    }
    private void homeintent() {
        Intent i = new Intent(splash.this, home.class);
        startActivity(i);
        finish();
    }
    @Override
    public void onBackPressed() {
      if(homeIntenthandler!=null)
        homeIntenthandler.removeCallbacksAndMessages(null)
        finish();
      }
    }

Handler.removeCallbacksAndMessages(null)基于相同

Answer 2

当你在线程中调用interrupt()方法时，当线程处于睡眠状态时，InterruptedException将被抛出。

你可以在线程内部检查它是否应该继续:

 Thread splashthread = new Thread() {
    @Override
    public void run() {
           while (shouldContinue) {
                  doSomeWork();
           }
   }
};

你可以在你的onBackPressed方法中将shouldContinue设置为false:

@Override
public void onBackPressed() {
       shouldContinue = false;
       finish();
}

Answer 3

我已经回答了你的问题。但是我建议你使用TimerTask和Timer而不是Thread。

Timer timer;
TimerTask timertask;
timer = new Timer();
timertask = new TimerTask() {
    @Override
    public void run() {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
               homeintent();        
            }
        });
    }
};
timer.schedule(timertask, 3000);
@Override
public void onBackPressed() {
    if(timertask!=null){
        timertask.cancel();
    }
    if(timer!=null){
        timer.cancel();
    }
    finish();
}

Answer 4

您可以创建一个volatile boolean检查来阻止线程进程，参见以下代码:

private volatile boolean cancelled = false;
Thread splashthread = new Thread() {
    @Override
    public void run() {
            if ( cancelled ) {
              return; // or handle this however you want
            }else{
              // do what ever you want to do here
            }
        }
};
splashthread.start();

在onBackPressed中这样做:

@Override
public void onBackPressed() {
    cancelled = true;
    finish();
}

建议使用volatile关键字，因为通常执行取消操作的线程不一定是被取消的线程。将boolean检查标记为volatile确保检查标志的线程将看到最新的值。