底部tab的返回退出和对话框

第一种：

private long exitTime = 0;

@Override
public boolean dispatchKeyEvent(KeyEvent event) {
if (event.getKeyCode() == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN) {
   if ((System.currentTimeMillis() - exitTime) > 2000) {
         Toast.makeText(getApplicationContext(), "再按一次退出程序",
           Toast.LENGTH_SHORT).show();
         exitTime = System.currentTimeMillis();
   } else {
          ActivityStack.create().AppExit(TabMainActivity.this);
   }
       return true;
 }

return super.dispatchKeyEvent(event);
}

第二种：

@Override
public boolean dispatchKeyEvent(KeyEvent event) {
if (event.getKeyCode() == KeyEvent.KEYCODE_BACK&& event.getAction()==KeyEvent.ACTION_DOWN) {
     showLoginOutDialog();
      return true;
}
    return super.dispatchKeyEvent(event);
}

/**
* 退出程序
*/
private void showLoginOutDialog() {
    AlertDialog.Builder dialog = new AlertDialog.Builder(this);
      dialog.setTitle("温馨提示");
      dialog.setMessage("您确定要退出客户端吗？");
      dialog.setPositiveButton("取消", new DialogInterface.OnClickListener() {
 public void onClick(DialogInterface dialog, int which) {
      dialog.dismiss();
 }
});
    dialog.setNegativeButton("确定", new DialogInterface.OnClickListener() {
 public void onClick(DialogInterface dialog, int which) {

MainActivity.this.finish();
     android.os.Process.killProcess(android.os.Process.myPid());
     System.exit(0);
 }
 }).create();
  dialog.show();
}