如果我需要将滑动标签视图与多个活动合并，我该怎么办？

时间：2014-11-27 20:32:22

标签： android

我正在关注在android studio中实现选项卡滑动视图的教程，它已经很好了。但后来我不得不使用标签滑动用于多个活动。例如，我有一个主要活动，在主要活动中我有3个按钮。点击一下，每个按钮都会打开另一个活动，其中包含4个标签。 主要行为＆gt;按钮1＆gt;屏幕标签1 2 3 主要活动＆gt;按钮2＆gt;带标签的屏幕4 5 6 （这些标签1 2 3 4 5 6实际上是活动）

更简单的版本可以在这里找到： http://easyway2in.blogspot.ae/2014/10/android-swipe-views-with-tabs.html

现在，我做的是： 我已经有了main_activity的fragmentpageadapter文件。我创建了fragmentpageadaptertwo用于另一个带有可跳转选项卡的活动。这就是我的fragmentpageadapter.java和fragmentpageadaptertwo.java的样子（BIG QUESTION ::我是否需要去除不同的碎片级别？）：

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
public class FragmentPageAdapter extends FragmentPagerAdapter {
public FragmentPageAdapter(FragmentManager fm) {
    super(fm);
}
@Override
public Fragment getItem(int arg0) {
    // TODO Auto-generated method stub
    switch (arg0) {
        case 0:
            return new in_room_dining();
        case 1:
            return new laundry();
        case 2:
            return new house_keeping();
        case 3:
            return new miscellaneous();
        default:
            break;
    }
    return null;
}
@Override
public int getCount() {
    // TODO Auto-generated method stub
    return 4;
}
}

这就是fragmentpagaadpatertwo.java的样子：

package com.appt.shreyabisht.staymax;

/**
 * Created by SHREYA BISHT on 11/28/2014.
 */
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
public class FragmentPageAdaptertwo extends FragmentPagerAdapter {
public FragmentPageAdaptertwo (FragmentManager fm) {
    super(fm);
}
@Override
public Fragment getItem(int arg0) {
    // TODO Auto-generated method stub
    switch (arg0) {
        case 0:
            return new gym();
        case 1:
            return new spa();
        case 2:
            return new recreational();
        case 3:
            return new events();
        default:
            break;
    }
    return null;
}
@Override
public int getCount() {
    // TODO Auto-generated method stub
    return 4;
}
}

会发生什么：当我运行我的应用程序时，它运行正常。主要活动打开。我点击按钮1，它应该带我到一个带有可跳转选项卡的屏幕，但此时应用程序崩溃了。

以下是我在logcat中看到的内容：

11-27 15:17:39.929      885-885/com.appt.shreyabisht.staymax E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.appt.shreyabisht.staymax, PID: 885
java.lang.RuntimeException: Unable to start activity    ComponentInfo{com.appt.shreyabisht.staymax/com.appt.shreyabisht.staymax.amn_menu}:     java.lang.NullPointerException
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
        at android.app.ActivityThread.access$800(ActivityThread.java:135)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5017)
        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:779)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
        at com.appt.shreyabisht.staymax.amn_menu.onCreate(amn_menu.java:23)
        at android.app.Activity.performCreate(Activity.java:5231)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
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:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
11-27 15:17:43.339      885-885/com.appt.shreyabisht.staymax I/Process﹕ Sending signal. PID: 885 SIG: 9
11-27 15:17:44.949    1103-1103/com.appt.shreyabisht.staymax D/dalvikvm﹕ GC_FOR_ALLOC freed 37K, 9% free 3606K/3940K, paused 103ms, total 105ms
11-27 15:17:45.689    1103-1103/com.appt.shreyabisht.staymax D/﹕ HostConnection::get() New Host Connection established 0xb8d6de20, tid 1103
11-27 15:17:45.749    1103-1103/com.appt.shreyabisht.staymax W/EGL_emulation﹕ eglSurfaceAttrib not implemented
11-27 15:17:45.759    1103-1103/com.appt.shreyabisht.staymax D/OpenGLRenderer﹕ Enabling debug mode 0

（amn_menu.java:23）是 viewpager.setAdapter（FT1）;

此时我的项目中有太多活动，如果我的问题不明确，我可以从我的活动中粘贴更多代码。感谢

\\\\\\\编辑\\\\\\\\\\\\\\\

amn_menu.java 

package com.appt.shreyabisht.staymax;


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 amn_menu extends FragmentActivity implements ActionBar.TabListener{
ActionBar actionbar;
ViewPager viewpager;
FragmentPageAdaptertwo ft1;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_amn_menu);
    viewpager = (ViewPager) findViewById(R.id.pager);
    ft1= new FragmentPageAdaptertwo (getSupportFragmentManager());
    actionbar = getActionBar();
    viewpager.setAdapter(ft1);
    actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
    actionbar.addTab(actionbar.newTab().setText("Gym").setTabListener(this));
    actionbar.addTab(actionbar.newTab().setText("Spa").setTabListener(this));
    actionbar.addTab(actionbar.newTab().setText("Recreational").setTabListener(this));
    actionbar.addTab(actionbar.newTab().setText("Events").setTabListener(this));
    viewpager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageSelected(int arg0) {
            actionbar.setSelectedNavigationItem(arg0);
        }
        @Override
        public void onPageScrolled(int arg0, float arg1, int arg2) {
            // TODO Auto-generated method stub
        }
        @Override
        public void onPageScrollStateChanged(int arg0) {
            // TODO Auto-generated method stub
        }
    });
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
    // TODO Auto-generated method stub
}
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
    viewpager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
    // TODO Auto-generated method stub
}
}

1 个答案:

答案 0 :(得分：0)

标识符似乎有错误。

19:   setContentView(R.layout.activity_amn_menu);
20:   viewpager = (ViewPager) findViewById(R.id.pager);  // <<-- here viewpager = null
21:   ft1= new FragmentPageAdaptertwo (getSupportFragmentManager());
22:   actionbar = getActionBar();
23:   viewpager.setAdapter(ft1);   // <--- NullPointerException HERE
24    actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

因此， R.id.pager Layour中不存在 R.layout.activity_amn_menu 。

查看layout/activity_amn_menu.xml R.id.pager元素，添加或修改第20行中的名称。

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