Question

我正在尝试第一次构建一个viewpager。我正在onCreate主方法中填充视图的ArrayList，并将其传递给PagerAdapter的构造函数。活动启动很好，我可以看到ViewPager（或至少它的背景），但没有任何视图出现在其中，我只看到空白背景。我已经尝试过膨胀布局XML，我知道它正在其他小部件中工作，所以它不是一个问题。我猜它与我编写instantiateObject方法的方式有关。无论如何，这是我的适配器：

    public class StoryAdapter extends PagerAdapter {
    private Context ctx;
    private ViewBuilder viewBuilder;

    public StoryAdapter(Context ctx, ArrayList<View> views){
        this.ctx = ctx;
    }


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

    @Override
    public boolean isViewFromObject(View arg0, Object arg1) {
        // TODO Auto-generated method stub
        return false;
    }

    @Override
    public Object instantiateItem(View arg0, int arg1) {
            View v = views.get(arg1);
            ((ViewPager) arg0).addView(v);
            return v;
            }

    @Override
    public void destroyItem(View pager, int arg1, Object view) {
    ((ViewPager) pager).removeView((View) view);

}
}

这是我的onCreate（）：

public class ShowStory extends Activity {
public int totalPages;
Button backBtn;
public String text;
public ArrayList<View> views;

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

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

    backBtn.setOnClickListener(new OnClickListener() {
        public void onClick(View view){
            Intent intent = new Intent();
            setResult(RESULT_CANCELED, intent);        
            finish();       
        }
    });
    ViewPager vp = (ViewPager)findViewById(R.id.storyFlipper);
    views = new ArrayList<View>();

    View v0 = getLayoutInflater().inflate(R.layout.galleryview, null);

    TextView v0t = (TextView)v0.findViewById(R.id.headline);
    v0t.setText("COVER1");

    View v1 = getLayoutInflater().inflate(R.layout.coverpage, null);
//      TextView v1t = (TextView)findViewById(R.id.coverText);
//      v1t.setText("COVER2");      

    View v2 = getLayoutInflater().inflate(R.layout.coverpage, null);
//      TextView v2t = (TextView)findViewById(R.id.coverText);
//      v2t.setText("COVER3");  

views.add(v0);
views.add(v1);
views.add(v2);  


    StoryAdapter sa = new StoryAdapter(this, views);        
    vp.setAdapter(sa);

PS我这样做主要是出于教育目的，这显然是一个非常简单的例子。任何帮助将不胜感激！

------编辑：我尝试了你的建议：

        @Override
    public Object instantiateItem(View collection, int position) {
    LayoutInflater inflater = (LayoutInflater) collection.getContext()
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    int resId = 0;
    switch (position) {

    case 0:
        resId = R.layout.coverpage;
        break;
    case 1:
        resId = R.layout.coverpage;
        break;
    case 2:
        resId = R.layout.coverpage;
        break;
    case 3:
        resId = R.layout.coverpage;
        break;

    }
    View view = inflater.inflate(resId, null);
    ((ViewPager) collection).addView(view, 0);
    return view;

    }

并得到相同的结果 - 我看到了viewpager的空白背景，但没有显示视图

Answer 1

我想通了 - 这是因为我在isViewFromObject方法中没有任何东西。用

替换null

return arg0 == (View) arg1;

解决了这个问题。

Answer 2

我认为需要在instantiateItems方法中夸大视图。我就这样做了：

@Override
public Object instantiateItem(View collection, int position) {
LayoutInflater inflater = (LayoutInflater) collection.getContext()
        .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

int resId = 0;
switch (position) {

case 0:
    resId = R.layout.first_layout_id;

    break;
case 1:
    resId = R.layout.layout_id;
    break;
case 2:
    resId = R.layout.layout_id;
    break;
case 3:
    resId = R.layout.layout_id;
    break;

}

View view = inflater.inflate(resId, null);
((ViewPager) collection).addView(view, 0);
return view;

}

视图未出现在viewpager中

2 个答案: