在使用view pager打开应用程序崩溃之前 - Android

时间：2015-04-07 15:55:19

标签： android android-fragments

这是我的第一个使用片段和页面滑动的应用。我正在尝试使用按钮和编辑文本创建三个布局。用户将能够在页面之间滑动。应该没有标签。问题是当我将应用程序上传到手机时，它会崩溃。我经历了一些教程并应用了相同的东西，除了他们没有添加按钮或编辑文本。在下面的代码中，我只包含了第一个片段，因为所有其他片段都是相似的。

主要活动Java：

package com.example.ibm.exoskeleton_2;
import com.example.ibm.exoskeleton_2.TabsPagerAdapter;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;

public class MainActivity extends FragmentActivity implements
        ActionBar.TabListener {

    private ViewPager viewPager;
    private TabsPagerAdapter mAdapter;
    private ActionBar actionBar;
    // Tab titles
    private String[] tabs = { "Top Rated", "Games", "Movies" };

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

        // Initilization
        viewPager = (ViewPager) findViewById(R.id.pager);
        actionBar = getActionBar();
       mAdapter = new TabsPagerAdapter(getSupportFragmentManager());

        viewPager.setAdapter(mAdapter);
       actionBar.setHomeButtonEnabled(false);


       // Adding Tabs
       /*for (String tab_name : tabs) {
            actionBar.addTab(actionBar.newTab().setText(tab_name)
                    .setTabListener(this));
        }*/

        /**
         * on swiping the viewpager make respective tab selected
         * */
        viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

            @Override
            public void onPageSelected(int position) {
                // on changing the page
                // make respected tab selected
                //actionBar.setSelectedNavigationItem(position);
            }

            @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) {
            }

            @Override
            public void onPageScrollStateChanged(int arg0) {
            }
        });
    }

    @Override
    public void onTabReselected(Tab tab, FragmentTransaction ft) {
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        // on tab selected
        // show respected fragment view
        viewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
    }

}

Android Manifist：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.ibm.exoskeleton_2" >
   <application
        android:allowBackup="true"
        android:icon="@mipmap/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>
    </application>

</manifest>

First Fragment：

package com.example.ibm.exoskeleton_2;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

/**
 * Created by IBM on 07-Apr-15.
 */
public class MainPage extends Fragment {
    Button start1,start2,start3;
    Button play1,play2,play3;
    Button stop1,stop2,stop3;
    Button tour;
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.main_page, container, false);
        start1 = (Button) rootView.findViewById(R.id.Start1Button);
        start2 = (Button) rootView.findViewById(R.id.Start2Button);
        start3 = (Button) rootView.findViewById(R.id.Start3Button);
        play1 = (Button) rootView.findViewById(R.id.Video1Button);
        play2 = (Button) rootView.findViewById(R.id.Video2Button);
        play3 = (Button) rootView.findViewById(R.id.Video3Button);
        stop1 = (Button) rootView.findViewById(R.id.Stop1Button);
        stop2 = (Button) rootView.findViewById(R.id.Stop2Button);
        stop3 = (Button) rootView.findViewById(R.id.Stop3Button);
        tour = (Button) rootView.findViewById(R.id.TourButton);
        return rootView;
    }
    public class ControllerFragment extends Fragment implements View.OnClickListener {
        @Override
        public void onClick(View v) {

        }
    }
}

First Fragment XML：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:weightSum="1">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Welcome"
        android:layout_marginTop="20dp"
        android:textSize="60dp"
        android:id="@+id/textView2" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text ="Tour"
        android:id="@+id/TourButton"
        android:layout_weight="0.10"
        android:textSize="30dp"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text ="Exercise 1"
        android:textSize="35dp"
        android:layout_margin="15dp"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0.16">
    <Button
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:id="@+id/Video1Button"
        android:text= "Play"
        android:layout_weight ="1"
        android:textSize="20dp"/>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:id="@+id/Start1Button"
            android:text= "Start"
            android:layout_weight ="1"
            android:textSize="20dp"/>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:id="@+id/Stop1Button"
            android:text= "Stop"
            android:layout_weight ="1"
            android:textSize="20dp"/>
    </LinearLayout>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Exercise 2"
        android:textSize="35dp"
        android:layout_margin="15dp"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0.19">
        <Button
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:id="@+id/Video2Button"
            android:text= "Play"
            android:layout_weight ="1"
            android:textSize="20dp"/>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:id="@+id/Start2Button"
            android:text= "Start"
            android:layout_weight ="1"
            android:textSize="20dp"/>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:id="@+id/Stop2Button"
            android:text= "Stop"
            android:layout_weight ="1"
            android:textSize="20dp"/>
        </LinearLayout>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Exercise 3"
        android:textSize="35dp"
        android:layout_margin="15dp"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0.17">
        <Button
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:id="@+id/Video3Button"
            android:text= "Play"
            android:layout_weight ="1"
            android:textSize="20dp"/>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:id="@+id/Start3Button"
            android:text= "Start"
            android:layout_weight ="1"
            android:textSize="20dp"/>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:id="@+id/Stop3Button"
            android:text= "Stop"
            android:layout_weight ="1"
            android:textSize="20dp"/>
    </LinearLayout>

</LinearLayout>

标签页适配器：

package com.example.ibm.exoskeleton_2;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
public class TabsPagerAdapter extends FragmentPagerAdapter {

    public TabsPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int index) {

        switch (index) {
        case 0:

            return new ExtraExercise();
        case 1:

            return new MainPage();
        case 2:

            return new OnYourOwn();
        }

        return null;
    }

    @Override
    public int getCount() {
        // get item count - equal to number of tabs
        return 3;
    }

}

Log Cat：

04-07 18:56:09.588  29377-29377/com.example.ibm.exoskeleton_2 I/Process﹕ Sending signal. PID: 29377 SIG: 9
04-07 18:57:44.871  30095-30095/com.example.ibm.exoskeleton_2 I/SELinux﹕ Function: selinux_android_load_priority [0], There is no sepolicy file.
04-07 18:57:44.901  30095-30095/com.example.ibm.exoskeleton_2 I/SELinux﹕ Function: selinux_android_load_priority , spota verifySig and checkHash pass. priority version is VE=SEPF_GT-I9505_4.4.2_0040
04-07 18:57:44.901  30095-30095/com.example.ibm.exoskeleton_2 I/SELinux﹕ selinux_android_seapp_context_reload: seapp_contexts file is loaded from /data/security/spota/seapp_contexts
04-07 18:57:44.901  30095-30095/com.example.ibm.exoskeleton_2 E/dalvikvm﹕ >>>>> Normal User
04-07 18:57:44.901  30095-30095/com.example.ibm.exoskeleton_2 E/dalvikvm﹕ >>>>> com.example.ibm.exoskeleton_2 [ userId:0 | appId:10253 ]
04-07 18:57:44.901  30095-30095/com.example.ibm.exoskeleton_2 D/dalvikvm﹕ Late-enabling CheckJNI
04-07 18:57:45.001  30095-30095/com.example.ibm.exoskeleton_2 W/ApplicationPackageManager﹕ getCSCPackageItemText()
04-07 18:57:45.011  30095-30095/com.example.ibm.exoskeleton_2 I/PersonaManager﹕ getPersonaService() name persona_policy
04-07 18:57:45.051  30095-30095/com.example.ibm.exoskeleton_2 D/AndroidRuntime﹕ Shutting down VM
04-07 18:57:45.051  30095-30095/com.example.ibm.exoskeleton_2 W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x418c1da0)
04-07 18:57:45.051  30095-30095/com.example.ibm.exoskeleton_2 E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.ibm.exoskeleton_2, PID: 30095
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ibm.exoskeleton_2/com.example.ibm.exoskeleton_2.MainActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2305)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
            at android.app.ActivityThread.access$900(ActivityThread.java:161)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            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:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.example.ibm.exoskeleton_2.MainActivity.onCreate(MainActivity.java:34)
            at android.app.Activity.performCreate(Activity.java:5426)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2269)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
            at android.app.ActivityThread.access$900(ActivityThread.java:161)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            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:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)
04-07 18:57:46.522  30095-30095/com.example.ibm.exoskeleton_2 I/Process﹕ Sending signal. PID: 30095 SIG: 9
04-07 19:34:52.119      356-356/com.example.ibm.exoskeleton_2 D/AndroidRuntime﹕ Shutting down VM
04-07 19:34:52.119      356-356/com.example.ibm.exoskeleton_2 W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x418c1da0)
04-07 19:34:52.119      356-356/com.example.ibm.exoskeleton_2 E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.ibm.exoskeleton_2, PID: 356
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ibm.exoskeleton_2/com.example.ibm.exoskeleton_2.MainActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2305)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
            at android.app.ActivityThread.access$900(ActivityThread.java:161)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            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:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.example.ibm.exoskeleton_2.MainActivity.onCreate(MainActivity.java:34)
            at android.app.Activity.performCreate(Activity.java:5426)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2269)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
            at android.app.ActivityThread.access$900(ActivityThread.java:161)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            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:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)
04-07 19:42:48.253    1897-1897/com.example.ibm.exoskeleton_2 W/ApplicationPackageManager﹕ getCSCPackageItemText()
04-07 19:42:48.253    1897-1897/com.example.ibm.exoskeleton_2 I/PersonaManager﹕ getPersonaService() name persona_policy
04-07 19:42:48.303    1897-1897/com.example.ibm.exoskeleton_2 D/AndroidRuntime﹕ Shutting down VM
04-07 19:42:48.303    1897-1897/com.example.ibm.exoskeleton_2 W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x418c1da0)
04-07 19:42:48.303    1897-1897/com.example.ibm.exoskeleton_2 E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.ibm.exoskeleton_2, PID: 1897
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ibm.exoskeleton_2/com.example.ibm.exoskeleton_2.MainActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2305)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
            at android.app.ActivityThread.access$900(ActivityThread.java:161)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            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:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.example.ibm.exoskeleton_2.MainActivity.onCreate(MainActivity.java:34)
            at android.app.Activity.performCreate(Activity.java:5426)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2269)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
            at android.app.ActivityThread.access$900(ActivityThread.java:161)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            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:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)

1 个答案:

答案 0 :(得分：0)

如果您将FragmentActivity替换为ActionBarActivity并使用getSupportActionBar()代替getActionBar()来解决问题。

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