Question

我在我的应用程序中使用Action Bar，扩展了ActionBarActivity，但它在Logcat中给出了以下错误，

02-12 21:59:53.252: E/AndroidRuntime(7062): FATAL EXCEPTION: main
02-12 21:59:53.252: E/AndroidRuntime(7062): Process: com.example.a_bar, PID: 7062
02-12 21:59:53.252: E/AndroidRuntime(7062): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.a_bar/com.example.a_bar.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.example.a_bar.MainActivity" on path: DexPathList[[zip file "/data/app/com.example.a_bar-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.example.a_bar-1, /system/lib, /data/downloads]]
02-12 21:59:53.252: E/AndroidRuntime(7062):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121)
02-12 21:59:53.252: E/AndroidRuntime(7062):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
02-12 21:59:53.252: E/AndroidRuntime(7062):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
02-12 21:59:53.252: E/AndroidRuntime(7062):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
02-12 21:59:53.252: E/AndroidRuntime(7062):     at android.os.Handler.dispatchMessage(Handler.java:102)
02-12 21:59:53.252: E/AndroidRuntime(7062):     at android.os.Looper.loop(Looper.java:136)
02-12 21:59:53.252: E/AndroidRuntime(7062):     at android.app.ActivityThread.main(ActivityThread.java:5021)
02-12 21:59:53.252: E/AndroidRuntime(7062):     at java.lang.reflect.Method.invokeNative(Native Method)
02-12 21:59:53.252: E/AndroidRuntime(7062):     at java.lang.reflect.Method.invoke(Method.java:515)
02-12 21:59:53.252: E/AndroidRuntime(7062):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827)
02-12 21:59:53.252: E/AndroidRuntime(7062):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
02-12 21:59:53.252: E/AndroidRuntime(7062):     at dalvik.system.NativeStart.main(Native Method)
02-12 21:59:53.252: E/AndroidRuntime(7062): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.a_bar.MainActivity" on path: DexPathList[[zip file "/data/app/com.example.a_bar-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.example.a_bar-1, /system/lib, /data/downloads]]

清单如下，

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.a_bar"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="11"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.a_bar.MainActivity"
            android:label="@string/app_name"
            android:theme="@style/Theme.AppCompat.Light" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

style.xml如下，

<resources>
 <style name="AppBaseTheme" parent="Theme.AppCompat.Light"> </style>
<style name="AppTheme" parent="AppBaseTheme"> </style>

</resources>

MainActivity如下，

package com.example.a_bar;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;

public class MainActivity extends ActionBarActivity {

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

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();
        }
    }

我在我的应用程序中添加了作为库项目android-support-v7-appcompat。并将主题添加到Manifest中，

 android:theme="@style/Theme.AppCompat.Light"

我的应用程序在声明时崩溃了。为什么生成ClassNotFoundException？但是当我扩展Activity而不是ActionBarActivity时，它正在运行。

Answer 1

无需导入android.support.v7.app.ActionBarActivity，因为项目的minSdkVersion为11，因此即使您不扩展ActionBarActivity，ActionBar也已包含在您的应用中。仅当您的应用程序的ActionBar 小于11 时，才需要为minSdkVersion导入支持库。

只需导入android.app.Activity并将您的课程扩展到Activity。

Answer 2

存在依赖性问题。添加support-v4库并希望它能解决您的问题。

虽然我正在扩展ActionBarActivity，但却给出了错误。为什么？

2 个答案: