如何在不崩溃的情况下中断 onBackPressed 线程？

Question

我已经尝试重写 onBackPressed 以不仅完成当前 activity，而且在我调用下一个 activity 的意图时中断线程。当我之前按下时，启动 activity 完成，但线程保持运行并将意图调用到下一个 activity。现在我已经在 BackPressed 上包含了线程中断，当我按回键时应用程序崩溃了。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：（此解决方案对我有用）。

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

当您在线程上调用 interrupt() 方法时，在睡眠状态下，将抛出 InterruptedException。

你可以在你的线程中检查天气它应该继续：

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

然后您可以在 onBackPressed 方法中将 shouldContinue 更改为 false：

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

Answer 2

Udi 我已经回答了你的问题。但我建议您使用 TimerTask and 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 3

您可以创建一个 volatile boolean 检查以阻止线程继续进行，请参见以下代码：

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();

然后在 onBackPressed 中做这样的事情：

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

建议使用 volatile 关键字，因为通常执行取消的线程不一定与被取消的线程相同。将 boolean 检查标记为 volatile 可确保检查标志的线程将看到最新值。

Answer 4

为了给您一个简洁的答案以及解释将来如何做，请看一下 Handler class and the 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) 基于为 same

提供的文档

如何在不崩溃的情况下中断 onBackPressed 线程？

How to interrupt a thread onBackPressed without crashing?

android

splash-screen

java-threads