如何在视图寻呼机中查找“最后一页”。或总的“观看次数”。 Android开发

Question

谢谢您对高级的帮助。很抱歉，如果这是一个非常愚蠢的问题，但是我在其他地方找不到。基本上，我想要确定的是确定ViewPager中所有页面的总数，就像我的代码一样。我尝试（在更高版本上）将“大小变量”添加到f作为参数（请参见FirstFragment）。这不是一个已知的数字，因为用户输入的是我将创建的表单（视图）的数量，并将其作为意图传递给FirstFragment。所以我试过了：

Fragment f = new UserFragment();
Bundle bundl = new Bundle();
bundl.putInt("pagenumbers", size);
f.setArguments(bundl);
lf.add(f); 

在FirstFragment内部。但是，当UserFragment在“ pagenumbers”下提取其参数时，它将返回0。然后，我尝试获取对FragmentAdapter内的getCount（）方法的访问权限，但是，由于需要时我位于UserFragment内，因此我不确定如何进行此操作。

[我正在尝试做的事情可能是帮助澄清，是我正在提取“当前页面信息”，这要归功于我的早期帖子以及所提供的帮助。现在，我要查看是否“当前页==大小（//这是页数。viewpager中的总视图）”。因此，在onClick方法中，您可以在UserFragment中看到它是否是最后一页，并且用户单击该按钮可以转到下一页。我希望它跳到另一个活动，在该活动中它处理从所有表单收集的所有SparseArray数据。 （虽然我需要有关如何将这个SparseArray数据放入意图的帮助，但我可能会对此提出一个新的问题...，因为它并不是很相关）。因此，如果您可以帮助我获得当前的工作尝试（如何正确地完成工作），或者只是建议一种全新的方法让我感到高兴。只要我能使它工作！

非常感谢您提供的所有帮助。请帮忙！

My UserFragment.java：

    package com.example.thinice;

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

public class UserFragment extends Fragment {


    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.layout_avgcalcform,
                container, false);
        final EditText markc = (EditText)rootView.findViewById(R.id.editTextASSMARK);
        final EditText marktotc = (EditText)rootView.findViewById(R.id.editTextASSTOT);
        final EditText assvalc = (EditText)rootView.findViewById(R.id.editTextASSWORTH);
        int currentviewnum =  ((FirstFragment) getActivity()).getPager().getCurrentItem();
        String pagenum = Integer.toString(currentviewnum);

           TextView tv = (TextView) rootView.findViewById(R.id.avg_testtv);
             tv.setText(pagenum);
        Button b = (Button) rootView.findViewById(R.id.button1);
        b.setOnClickListener( new View.OnClickListener(){

               public void onClick(View v){

        int currentviewnum =  ((FirstFragment)    getActivity()).getPager().getCurrentItem();
                   ((FirstFragment) getActivity()).saveData(new  Question(markc.getText().toString(),marktotc.getText().toString(),assvalc.getText().toString()));
                   ((FirstFragment) getActivity()).getPager().setCurrentItem(currentviewnum+1);



               }
    });
        return rootView;

    }   

}

如果您需要查看更多我的代码，请告诉我。但这真的让我很烦。因此，如果有人可以帮助我，那就太好了！非常感谢您。

FragmentAdapter.java：

     package com.example.thinice;

import java.util.ArrayList;
import java.util.List;

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

public class FragmentAdapter extends FragmentPagerAdapter{


    private List<Fragment> fragments;



    public FragmentAdapter(FragmentManager fragmentManager, ArrayList<Fragment> fragments) {
        super(fragmentManager);
            this.fragments = fragments;
    }

    @Override
    public Fragment getItem(int position) {
        //Bundle args = new Bundle();
        //args.putInt("page_position", position+1);
        //((Fragment) fragments).setArguments(args);
        return this.fragments.get(position);
    }

    @Override
    public void destroyItem (ViewGroup container, int position, Object object)
    {
        super.destroyItem(container, position, object);
    }

    @Override
    public int getCount() {
       return this.fragments.size();
    }
}

FirstFragment.java（这是我的活动）：

    package com.example.thinice;



import java.util.ArrayList;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.util.SparseArray;
import android.widget.Button;

public class FirstFragment extends FragmentActivity 
  {

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_viewpager);

        // Check whether the activity is using the layout version with
        // the fragment_container FrameLayout. If so, we must add the first fragment
        int size = getIntent().getExtras().getInt("numass1");
        ViewPager vp = (ViewPager) findViewById(R.id.viewPager);



            if (savedInstanceState != null) {
                return;
            }

            ArrayList<Fragment> lf = new ArrayList<Fragment>();
            for(int count=0; count<size; count ++){

                Fragment f = new UserFragment();
                lf.add(f);







            }

 FragmentAdapter hello = new FragmentAdapter(getSupportFragmentManager() , lf);
            vp.setAdapter(hello);
          //  vp.setOffscreenPageLimit(size);


        }

    SparseArray<Question> questions = new SparseArray<Question>();
    public void saveData(Question quest){
        ViewPager vp = (ViewPager) findViewById(R.id.viewPager);
           questions.put(vp.getCurrentItem(), quest);

    }
    public ViewPager getPager() {
        ViewPager vp = (ViewPager) findViewById(R.id.viewPager);
        return vp;
    }




    }

编辑：建议的LOGCAT文件：

07-06 20:51:50.241: D/AndroidRuntime(8151): Shutting down VM
07-06 20:51:50.241: W/dalvikvm(8151): threadid=1: thread exiting with uncaught exception    (group=0x415a4ba8)
07-06 20:51:50.251: E/AndroidRuntime(8151): FATAL EXCEPTION: main
07-06 20:51:50.251: E/AndroidRuntime(8151): Process: com.example.thinice, PID: 8151
07-06 20:51:50.251: E/AndroidRuntime(8151): java.lang.NullPointerException
07-06 20:51:50.251: E/AndroidRuntime(8151):     at com.example.thinice.UserFragment.onCreateView(UserFragment.java:34)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.support.v4.view.ViewPager.populate(ViewPager.java:1068)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.View.measure(View.java:16497)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.View.measure(View.java:16497)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:327)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.View.measure(View.java:16497)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.View.measure(View.java:16497)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1912)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1109)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1291)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:996)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5600)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.Choreographer.doCallbacks(Choreographer.java:574)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.Choreographer.doFrame(Choreographer.java:544)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.os.Handler.handleCallback(Handler.java:733)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.os.Handler.dispatchMessage(Handler.java:95)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.os.Looper.loop(Looper.java:136)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at android.app.ActivityThread.main(ActivityThread.java:5001)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at java.lang.reflect.Method.invokeNative(Native Method)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at java.lang.reflect.Method.invoke(Method.java:515)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
07-06 20:51:50.251: E/AndroidRuntime(8151):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

您应该使用ViewPager.getAdapter（）。getCount（）getAdapter（）方法返回为ViewPager提供页面的对象。

Answer 2

在OnCreate（）中：

 ViewPager vp = (ViewPager) findViewById(R.id.viewPager);


System.out.println(vp.getChildCount());

以下代码对我来说很好用：

public class ViewFlipperMainActivity extends Activity {
    private ViewFlipper viewFlipper;
    private float lastX;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE); 
        setContentView(R.layout.help_flipper);
        viewFlipper = (ViewFlipper) findViewById(R.id.view_flipper);    
        System.out.println(viewFlipper.getChildCount());
    }
}

Answer 3

在创建ViewPager时设置setOffscreenPageLimit。

    int cont = list.size()
    mViewPager.setOffscreenPageLimit(cont);

然后您可以通过]访问>

mViewPager.getOffscreenPageLimit()