android - PopupWindow 抛出 BadTokenException

Question

如果我直接在oCreate()中添加showPopupWindow();，会报错:

android.view.WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running?

如下所示:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btn = (Button) findViewById(R.id.btn);

    showPopupWindow();
    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
             showPopupWindow();
        }
    });
}

private void showPopupWindow() {
    TextView textView = new TextView(this);
    textView.setText("This is a Text");
    textView.setTextSize(20);
    textView.setTextColor(Color.parseColor("#33000000"));
    //悬浮窗体
    popupWindow = new PopupWindow(textView,-2,-2);
    //设置View
    popupWindow.setContentView(textView);
    //设置宽高
    //必须设置背景
    popupWindow.setBackgroundDrawable(new ColorDrawable(Color.BLUE));
    //父窗体，Gravity，位置（x距离左边的距离，y距离上边的距离）
    popupWindow.showAtLocation(findViewById(R.id.rl_main), Gravity.LEFT + Gravity.TOP, 60, 60);

}

但是如果我将它添加到onClick中，就可以了，如下所示:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btn = (Button) findViewById(R.id.btn);

    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            showPopupWindow();
        }
    });
}

private void showPopupWindow() {
    TextView textView = new TextView(this);
    textView.setText("This is a Text");
    textView.setTextSize(20);
    textView.setTextColor(Color.parseColor("#33000000"));
    //悬浮窗体
    popupWindow = new PopupWindow(textView,-2,-2);
    //设置View
    popupWindow.setContentView(textView);
    //设置宽高
    //必须设置背景
    popupWindow.setBackgroundDrawable(new ColorDrawable(Color.BLUE));
    //父窗体，Gravity，位置（x距离左边的距离，y距离上边的距离）
    popupWindow.showAtLocation(findViewById(R.id.rl_main), Gravity.LEFT + Gravity.TOP, 60, 60);

}

请帮助我理解它。

Answer 1

我会说在 onCreate() 方法中显示弹出窗口还为时过早，因为在那之前， Activity 可能还没有完成所需的生命周期。您需要通过实现几分之一秒的延迟来区分您的解决方案。