Android 我刷卡时应用程序崩溃_Android_Android Fragments

Android 我刷卡时应用程序崩溃

android android-fragments

Android 我刷卡时应用程序崩溃,android,android-fragments,Android,Android Fragments,我正在研究android碎片。昨天我编写了和现在一样的代码，但今天它崩溃了。我包括代码，请看看你是否能抓住它的错误主要碎片活动的代码 package com.example.fragmentswithswipetabs; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.

我正在研究android碎片。昨天我编写了和现在一样的代码，但今天它崩溃了。我包括代码，请看看你是否能抓住它的错误主要碎片活动的代码

package com.example.fragmentswithswipetabs;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;

public class MainActivity extends FragmentActivity {
    ViewPager viewpager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        viewpager = (ViewPager) findViewById(R.id.viewPager);
        viewpager.setAdapter(new CustomAdapter(getSupportFragmentManager()));
    }

    public class CustomAdapter extends FragmentPagerAdapter {

        public CustomAdapter(FragmentManager fm) {
            super(fm);
            // TODO Auto-generated constructor stub
        }

        @Override
        public Fragment getItem(int i) {
            // TODO Auto-generated method stub
            Fragment fragment = null;
            switch (i) {
            case 0:
                fragment = new FragmentA();
                break;
            case 1:
                fragment = new FragmentB();
                break;
            case 3:
                fragment = new FragmentC();
                break;
            }
            return fragment;
        }

        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return 3;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            // TODO Auto-generated method stub
            if (position == 0) {
                return "Tab 1";
            } else if (position == 1) {
                return "Tab 2";
            } else if(position == 2){
                return "Tab 3";
            }
            return null;
        }

    }
}

activity_main.xml的代码

<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/viewPager"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <android.support.v4.view.PagerTitleStrip
        android:id="@+id/viewPagerStrip"
        android:layout_width="fill_parent"
        android:layout_height="40dip"
        android:layout_gravity="top"
        android:background="#DDDDDD"
        android:gravity="center" >
    </android.support.v4.view.PagerTitleStrip>

</android.support.v4.view.ViewPager>

记录Cat信息

07-04 07:07:05.204: D/dalvikvm(150): GC_EXPLICIT freed 100K, 51% free 2975K/5959K, external 1289K/1546K, paused 96ms
07-04 07:07:05.394: D/AndroidRuntime(799): Shutting down VM
07-04 07:07:05.394: W/dalvikvm(799): threadid=1: thread exiting with uncaught exception (group=0x40015560)
07-04 07:07:05.404: E/AndroidRuntime(799): FATAL EXCEPTION: main
07-04 07:07:05.404: E/AndroidRuntime(799): java.lang.NullPointerException
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.app.BackStackRecord.doAddOp(BackStackRecord.java:394)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.app.BackStackRecord.add(BackStackRecord.java:389)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:99)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:832)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.view.ViewPager.populate(ViewPager.java:1048)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.view.ViewPager$3.run(ViewPager.java:244)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.os.Handler.handleCallback(Handler.java:587)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.os.Handler.dispatchMessage(Handler.java:92)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.os.Looper.loop(Looper.java:123)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.app.ActivityThread.main(ActivityThread.java:3683)
07-04 07:07:05.404: E/AndroidRuntime(799):  at java.lang.reflect.Method.invokeNative(Native Method)
07-04 07:07:05.404: E/AndroidRuntime(799):  at java.lang.reflect.Method.invoke(Method.java:507)
07-04 07:07:05.404: E/AndroidRuntime(799):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-04 07:07:05.404: E/AndroidRuntime(799):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-04 07:07:05.404: E/AndroidRuntime(799):  at dalvik.system.NativeStart.main(Native Method)
07-04 07:07:05.404: W/ActivityManager(61):   Force finishing activity com.example.fragmentswithswipetabs/.MainActivity
07-04 07:07:05.924: W/ActivityManager(61): Activity pause timeout for HistoryRecord{40543390 com.example.fragmentswithswipetabs/.MainActivity}

请注意，我包括三个片段，每个片段都有一个简单的文本视图。

应用程序启动，当我滑动到其他片段时，它崩溃了，因为FragmentStatePagerAdapter。在片段中，我们需要分离getChildFragmentManager

因此，我们需要在activityCreated（）之后添加以下代码

不应该有第三种情况，应该是第二种情况：

请在您的问题中添加日志。我使用的是FramentPagerAdapter而不是FragmentStatePagerAdapter。没问题：）。尽管如此，投票支持也将非常受欢迎；）

07-04 07:07:05.204: D/dalvikvm(150): GC_EXPLICIT freed 100K, 51% free 2975K/5959K, external 1289K/1546K, paused 96ms
07-04 07:07:05.394: D/AndroidRuntime(799): Shutting down VM
07-04 07:07:05.394: W/dalvikvm(799): threadid=1: thread exiting with uncaught exception (group=0x40015560)
07-04 07:07:05.404: E/AndroidRuntime(799): FATAL EXCEPTION: main
07-04 07:07:05.404: E/AndroidRuntime(799): java.lang.NullPointerException
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.app.BackStackRecord.doAddOp(BackStackRecord.java:394)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.app.BackStackRecord.add(BackStackRecord.java:389)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:99)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:832)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.view.ViewPager.populate(ViewPager.java:1048)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.support.v4.view.ViewPager$3.run(ViewPager.java:244)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.os.Handler.handleCallback(Handler.java:587)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.os.Handler.dispatchMessage(Handler.java:92)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.os.Looper.loop(Looper.java:123)
07-04 07:07:05.404: E/AndroidRuntime(799):  at android.app.ActivityThread.main(ActivityThread.java:3683)
07-04 07:07:05.404: E/AndroidRuntime(799):  at java.lang.reflect.Method.invokeNative(Native Method)
07-04 07:07:05.404: E/AndroidRuntime(799):  at java.lang.reflect.Method.invoke(Method.java:507)
07-04 07:07:05.404: E/AndroidRuntime(799):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-04 07:07:05.404: E/AndroidRuntime(799):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-04 07:07:05.404: E/AndroidRuntime(799):  at dalvik.system.NativeStart.main(Native Method)
07-04 07:07:05.404: W/ActivityManager(61):   Force finishing activity com.example.fragmentswithswipetabs/.MainActivity
07-04 07:07:05.924: W/ActivityManager(61): Activity pause timeout for HistoryRecord{40543390 com.example.fragmentswithswipetabs/.MainActivity}

   @Override
public void onDetach() {
    super.onDetach();
    try {
        Field childFragmentManager = Fragment.class.getDeclaredField("mChildFragmentManager");
        childFragmentManager.setAccessible(true);
        childFragmentManager.set(this, null);
    } catch (NoSuchFieldException e) {
        throw new RuntimeException(e);
    } catch (IllegalAccessException e) {
        throw new RuntimeException(e);
    }
}

        case 0:
            fragment = new FragmentA();
            break;
        case 1:
            fragment = new FragmentB();
            break;
        case 3:
            fragment = new FragmentC();
            break;