Android 找不到 activity，即使它已在清单中声明

Question

我正在尝试启动一个带有意图的 activity，但它找不到 activity。这很奇怪，因为我在清单中声明了 activity。我做了其他 Whosebug 帖子建议的所有事情：我更新了 Android Studio，更新了 SDK 工具，并检查了逻辑错误。没有什么。我不知道是怎么回事。这是我的代码：

Intent mIntent = new Intent(this, ItemsActivity.class);

@Override
protected void onCreate(Bundle savedInstanceState) {
    ...

    Button button2 = (Button) findViewById(R.id.button2);
    button2.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            String[] itemsArray = new String[items.size()];
            String[] quantitiesArray = new String[quantities.size()];

            for (int i = 0; i < items.size(); i++) {
                itemsArray[i] = items.get(i);
                quantitiesArray[i] = quantities.get(i);
            }

            Bundle extras = new Bundle();
            extras.putStringArray("items", itemsArray);
            extras.putStringArray("quantities", quantitiesArray);
            //mIntent.putExtras(extras);
            startActivity(mIntent);
        }
    });

这是清单：

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <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
        android:name=".ItemsActivity"
        android:label="@string/list_name">
    </activity>
</application>

一切正确；我调试以确保没有其他错误。一切正常，就是找不到activity。这是日志中的实际错误：

04-03 22:45:40.846  27796-27796/com.example.android.hackathonapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.android.hackathonapp, PID: 27796
android.content.ActivityNotFoundException: Unable to find explicit activity class {/com.example.android.hackathonapp.ItemsActivity}; have you declared this activity in your AndroidManifest.xml?
        at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1636)
        at android.app.Instrumentation.execStartActivity(Instrumentation.java:1430)
        at android.app.Activity.startActivityForResult(Activity.java:3532)
        at android.app.Activity.startActivityForResult(Activity.java:3493)
        at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:817)
        at android.app.Activity.startActivity(Activity.java:3735)
        at android.app.Activity.startActivity(Activity.java:3703)
        at com.example.android.hackathonapp.MainActivity.onClick(MainActivity.java:56)
        at android.view.View.performClick(View.java:4654)
        at android.view.View$PerformClick.run(View.java:19438)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:146)
        at android.app.ActivityThread.main(ActivityThread.java:5602)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
        at dalvik.system.NativeStart.main(Native Method)

我完全卡住了。有人可以帮帮我吗？提前致谢:)

Answer 1

这里：

Intent mIntent = new Intent(this, ItemsActivity.class);

导致问题的行，因为在 Activity 创建之前将 this 作为第一个参数传递。

在任何方法中而不是在 class 级别准备 Intent 以获得 Activity 的有效上下文：

@Override
protected void onCreate(Bundle savedInstanceState) {
 ....
 // Prepare Intent here
 final Intent mIntent = new Intent(this, ItemsActivity.class);
 ....
}

Android 找不到 activity，即使它已在清单中声明

Android can't find an activity, even though it's declared in the manifest

android

android-manifest

android-activity