java - 使用 Fragment 库扩充类 fragment 时出错

Question

我正在尝试测试 Fragment 类，但不知何故，我的程序不断引发 Error Inflating 类 fragment 。我知道有关此错误的问题已被反复询问，但我发现答案没有帮助。由于我不需要对 API < 11 的支持，我正在使用 android.app.Activity 库和 android.app.Fragment 库，它们具有 getFragmentManager() 方法。我自己在我的代码中没有发现任何问题，所以任何人都可以帮助我吗？

主 Activity .java

import android.app.Activity;
import android.app.Fragment;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {

Fragment fragment1;
Button button1;

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

    fragment1 = new MainActivityFragment1();

    button1 = (Button) findViewById(R.id.button1);

    button1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            getFragmentManager().beginTransaction()
                    .replace(R.id.fragment, fragment1)
                    .commit();
        }
    });

MainAcitivityFragment1.java

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


public class MainActivityFragment1 extends Fragment {

public MainActivityFragment1() {
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment1, container, false);
}
}

fragment 1.xml

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">

        <Button
            android:id="@+id/button1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="1ST"
            android:onClick="onClick1"/>

    </LinearLayout>

    <fragment
        android:id="@+id/fragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

这是我的 logcat，以备不时之需:

08-27 12:17:35.040    2290-2290/com.example.samplefragmentbasic E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.samplefragmentbasic, PID: 2290
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.samplefragmentbasic/com.example.samplefragmentbasic.MainActivity}: android.view.InflateException: Binary XML file line #32: Error inflating class fragment
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
        at      `android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
        at android.app.ActivityThread.access$800(ActivityThread.java:151)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5257)
        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:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
 Caused by: android.view.InflateException: Binary XML file line #32: Error inflating class fragment
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:763)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
        at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:378)
        at android.app.Activity.setContentView(Activity.java:2145)
        at com.example.samplefragmentbasic.MainActivity.onCreate(MainActivity.java:19)
        at android.app.Activity.performCreate(Activity.java:5990)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
            at android.app.ActivityThread.access$800(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5257)
            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:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
 Caused by: java.lang.NullPointerException
        at java.lang.VMClassLoader.findLoadedClass(Native Method)
        at java.lang.ClassLoader.findLoadedClass(ClassLoader.java:362)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:499)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
        at android.app.Fragment.instantiate(Fragment.java:604)
        at android.app.Fragment.instantiate(Fragment.java:582)
        at android.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2108)
        at android.app.Activity.onCreateView(Activity.java:5328)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:733)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
            at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:378)
            at android.app.Activity.setContentView(Activity.java:2145)
            at com.example.samplefragmentbasic.MainActivity.onCreate(MainActivity.java:19)
            at android.app.Activity.performCreate(Activity.java:5990)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
            at android.app.ActivityThread.access$800(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5257)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)

Answer 1

@syk:仅供引用

使用此 android.support.v4.app.Fragment 代替 import android.app.Fragment;。对于您的 fragment 部分。

并使用 FragmentActivity 代替 Activity

public class MainActivity extends FragmentActivity {

并导入这个

android.support.v4.app.FragmentActivity