0

这是一个简单的项目。我正在使用 2 个活动。

  1. 主要活动
  2. 新活动

我为 MainActivity 做了 3 个别名

  • 红色的
  • 蓝色的
  • 绿色

我想根据我制作的活动别名更改启动器的图标和标签。为此，我在新活动中制作了 3 个按钮。MainActivity 只是调用 NewActivity。但该应用程序只是崩溃生成错误

这是 manifest.xml：

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

    <application
        android:allowBackup="true"
        android:enabled="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <activity
            android:name=".NewActivity"
            android:label="@string/app_name" />

        <activity
            android:name=".MainActivity"
            android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity-alias
            android:name=".RED"
            android:enabled="true"
            android:icon="@drawable/red"
            android:label="Red app"
            android:targetActivity=".MainActivity">

        </activity-alias>

        <activity-alias
            android:name=".BLUE"
            android:enabled="false"
            android:icon="@drawable/blue"
            android:label="Blue app"
            android:targetActivity=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity-alias>

        <activity-alias
            android:name=".GREEN"
            android:enabled="false"
            android:icon="@drawable/green"
            android:label="Green app"
            android:targetActivity=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity-alias>


    </application>

</manifest>

这是 MainActivity.java：

package com.example.app_alias_check;

import android.content.Intent;
import android.os.Bundle;
import android.os.PersistableBundle;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

class MainActivity extends AppCompatActivity {
    @Override
    public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState) {
        super.onCreate(savedInstanceState, persistentState);
        Intent intent = new Intent(this, NewActivity.class);
        startActivity(intent);
    }
}

这是NewActivity.java：

package com.example.app_alias_check;

import androidx.appcompat.app.AppCompatActivity;

import android.content.ComponentName;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class NewActivity extends AppCompatActivity implements View.OnClickListener {

     private String []iconColour = {"RED", "GREEN",  "BLUE"};
    private Button bRed, bGreen, bBlue;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_new);
        bRed = findViewById(R.id.btn_red);
        bGreen = findViewById(R.id.btn_green);
        bBlue = findViewById(R.id.btn_blue);
        bRed.setOnClickListener(this);
        bGreen.setOnClickListener(this);
        bBlue.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.btn_red:
                setIcon("Red");
                break;
            case R.id.btn_green:
                setIcon("Green");
                break;
            case R.id.btn_blue:
                setIcon("Blue");
                break;
        }
    }

    private void setIcon(String targetColour) {
        int action;
        for (String value : iconColour) {
            if (value.equals(targetColour))
                action = PackageManager.COMPONENT_ENABLED_STATE_ENABLED;
            else
                action = PackageManager.COMPONENT_ENABLED_STATE_DISABLED;

            ComponentName componentName = new ComponentName(BuildConfig.APPLICATION_ID, BuildConfig.APPLICATION_ID + value);
            getPackageManager().setComponentEnabledSetting(
                    componentName,
                    action, PackageManager.DONT_KILL_APP);
        }
    }


}

这是activity_new.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=".NewActivity">

    <Button
        android:id="@+id/btn_red"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Red"
        app:layout_constraintBottom_toTopOf="@+id/btn_green"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.501"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/btn_blue"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Blue"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.501"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btn_green" />

    <Button
        android:id="@+id/btn_green"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Green"
        app:layout_constraintBottom_toTopOf="@+id/btn_blue"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.501"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btn_red" />

</androidx.constraintlayout.widget.ConstraintLayout>

这是错误日志：

    --------- beginning of crash
07-17 20:06:49.420 3047-3047/com.example.app_alias_check E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.app_alias_check, PID: 3047
    java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.app_alias_check/com.example.app_alias_check.MainActivity}: java.lang.IllegalAccessException: class com.example.app_alias_check.MainActivity is not accessible from class android.app.Instrumentation
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
        at android.app.ActivityThread.access$800(ActivityThread.java:144)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5221)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: java.lang.IllegalAccessException: class com.example.app_alias_check.MainActivity is not accessible from class android.app.Instrumentation
        at java.lang.Class.newInstance(Class.java:1557)
        at android.app.Instrumentation.newActivity(Instrumentation.java:1065)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2199)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
        at android.app.ActivityThread.access$800(ActivityThread.java:144) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:135) 
        at android.app.ActivityThread.main(ActivityThread.java:5221) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at java.lang.reflect.Method.invoke(Method.java:372) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 

我不知道是否允许为一个活动创建多个别名或只允许一个别名？

4

1 回答 1

0

<activity-alias>允许多个。

您需要声明MainActivity为一个public类。将public关键字添加到

class MainActivity extends AppCompatActivity {
于 2020-07-18T20:14:36.417 回答