Android onBackPressed不执行的解决方案

   /**
     * 再次返回键退出程序
     */
    private long lastBack = 0;

  @Override
    public void onBackPressed() {
        if (lastBack == 0 || System.currentTimeMillis() - lastBack > 2000) {
            Toast.makeText(getApplicationContext(), "再按一次返回退出程序", Toast.LENGTH_SHORT).show();
            lastBack = System.currentTimeMillis();
            return;
        }
        super.onBackPressed();
    }

onBackPressed()在Activity.class里实现：

    public void onBackPressed() {
        finish();
    }

  @Override
    public boolean dispatchKeyEvent(KeyEvent event)
    {
        if (event.getKeyCode() == KeyEvent.KEYCODE_BACK &&  event.getAction()==KeyEvent.ACTION_DOWN){
            //自己的操作
            if (lastBack == 0 || System.currentTimeMillis() - lastBack > 2000) {
                Toast.makeText(getApplicationContext(), "再按一次返回退出程序", Toast.LENGTH_SHORT).show();
                lastBack = System.currentTimeMillis();

            }else {
                finish();
            }
            return false;
        }
        return super.dispatchKeyEvent(event);
    }