android按兩次傳回鍵退出程式

方法一：

建立一個baseActivity，然後讓其他的activity繼承它

之後在baseActivity中加入以下代碼代碼即可

<span style="font-size:18px;">@Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		if(keyCode == KeyEvent.KEYCODE_BACK){
			exit();
			return false;
		}
		return super.onKeyDown(keyCode, event);
	}

	private void exit() {
		if((System.currentTimeMillis()-exitTime) > 2000){
			Toast.makeText(getBaseContext(), "再按一次退出程式", Toast.LENGTH_LONG).show();
			exitTime = System.currentTimeMillis();
		}else{
			finish();
			System.exit(0);
		}
	}</span>
           

方法二：

判斷兩次點選傳回鍵的時間差，如果小于一定時間，如2秒，則退出函數

<span style="font-size:18px;"> private long firstTime = 0;
    @Override
 public boolean onKeyUp(int keyCode, KeyEvent event) {
        // TODO Auto-generated method stub
        switch(keyCode)
        {
        case KeyEvent.KEYCODE_BACK:
             long secondTime = System.currentTimeMillis(); 
              if (secondTime - firstTime > 2000) {                                         //如果兩次按鍵時間間隔大于2秒，則不退出
                  Toast.makeText(this, "再按一次退出程式", Toast.LENGTH_SHORT).show(); 
                  firstTime = secondTime;//更新firstTime
                  return true; 
              } else {                                                    //兩次按鍵小于2秒時，退出應用
             System.exit(0);
              } 
            break;
        }
      return super.onKeyUp(keyCode, event);
    }
</span>
           

方法三：

利用線程延時處理

private int mBackKeyPressedTimes = 0;

        @Override
        public void onBackPressed() {
                if (mBackKeyPressedTimes == 0) {
                        Toast.makeText(this, "再按一次退出程式 ", Toast.LENGTH_SHORT).show();
                        mBackKeyPressedTimes = 1;
                        new Thread() {
                                @Override
                                public void run() {
                                        try {
                                                Thread.sleep(2000);
                                        } catch (InterruptedException e) {
                                                e.printStackTrace();
                                        } finally {
                                                mBackKeyPressedTimes = 0;
                                        }
                                }
                        }.start();
                        return;
                      else{
                               this.activity.finish();
                            }
                }
                super.onBackPressed();
        }