我正在尝试编写一个 Android 应用程序,当您单击按钮时,它会将文本输入控制台,但是当我编译它并在运行 7.0 API 版本 24 的 Galaxy S7 Edge 上运行它时,我收到错误.
I've read that I need to add something into the manifest file但我不确定我需要添加什么。
FATAL EXCEPTION: main Process: me.adamstephenson.test.test1, PID: 16405 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{me.adamstephenson.test.test1/me.adamstephenson.test.test1.MainActivity}: java.lang.ClassCastException: me.adamstephenson.test.test1.MainActivity cannot be cast to android.app.Activity
package me.adamstephenson.test.test1;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
public class MainActivity {
public class MyActivity extends Activity {
protected void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.activity_main);
final Button button = (Button) findViewById(R.id.RequestKey);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Log.d("RequestKey", "Clicked");
}
});
}
}
}
这是布局
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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="me.adamstephenson.test.test1.MainActivity">
<Button
android:id="@+id/RequestKey"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
tools:layout_editor_absoluteX="196dp"
tools:layout_editor_absoluteY="129dp" />
</android.support.constraint.ConstraintLayout>
最后是 list 文件
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="me.adamstephenson.test.test1">
<application
android:allowBackup="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=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
最佳答案
您在 list 中引用了错误的类。 MyActivity
是 Activity,而不是 MainActivity
。将您的 list 更改为以下内容:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="me.adamstephenson.test.test1">
<application
android:allowBackup="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=".MainActivity$MyActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
还有
你也应该让你的内心 Activity 静态
:
public class MainActivity {
public static class MyActivity extends Activity {
...
}
}
关于java.lang.RuntimeException : Unable to instantiate activit,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/42728010/