Android-Java 为什么浮动小部件覆盖按钮不可见并且代码没有错误？

Question

我尝试制作浮动小部件覆盖按钮 - 就像信使个人资料照片小部件一样，当有人向您发送消息时会显示该小部件。我使用了这些文件。 当我运行程序时，代码中没有任何无效内容。我看到带有按钮的应用程序，但单击后没有任何可见内容。

MainActivity.java：

package com.example.mywidget;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        startFloatingWidgetService();

        };


    private void startFloatingWidgetService() {
        Intent intent = new Intent(this, FloatingWidgetService.class);
        startService(intent);
    }
};

FloatingWidgetService.java

package com.example.mywidget; 

import android.app.Service;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.os.IBinder;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.LinearLayout;

public class FloatingWidgetService extends Service {

    private WindowManager mWindowManager;
    private View mFloatingWidgetView;

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        mFloatingWidgetView = LayoutInflater.from(this).inflate(R.layout.floating_widget_layout, null);

        // Inicializace tlačítka
        Button button = mFloatingWidgetView.findViewById(R.id.floating_button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
              
                showTextDialog();
            }
        });

        // Inicializace WindowManager
        mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
        WindowManager.LayoutParams params = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY, 
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT
        );

        params.gravity = Gravity.BOTTOM | Gravity.END;
        mWindowManager.addView(mFloatingWidgetView, params);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mFloatingWidgetView != null && mWindowManager != null) {
            mWindowManager.removeView(mFloatingWidgetView);
        }
    }

    private void showTextDialog() {

    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/start_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Start Floating Widget Service" />


</androidx.constraintlayout.widget.ConstraintLayout>

floating_widget_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <Button
        android:id="@+id/floating_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="dfdsfdasdfasdfAFASD"
        android:layout_gravity="end"
        android:background="@android:color/holo_red_light"/>

</LinearLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>


    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/Theme.Mywidget"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Answer 1

FloatingWidgetService.java 中的 showTextDialog() 方法是空的，这就是为什么当你调用这个空方法时什么也没有出现：

 private void showTextDialog() {

    }

尝试测试它是否正常工作，然后将其替换为您想要的代码：

private void showTextDialog() {
    Toast.makeText(this, "Button clicked!", Toast.LENGTH_SHORT).show();
}