ViewPager

ViewPager的使用

當第一次使用某個軟件時，會一頁頁地翻，翻了三到五頁後，點擊立即體驗，纔會進入這個軟件，這就是ViewPager。
需要寫一個ViewPagerAdapter,繼承PagerAddapter,然後重寫他的四個方法。

public class ViewPagerAdapter extends PagerAdapter {
    private List<View> views;
    public ViewPagerAdapter(List<View> views){
        this.views = views;
    }

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

    @Override
    public boolean isViewFromObject(View arg0, Object arg1) {

        return arg0==arg1;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {

//      super.destroyItem(container, position, object);
        container.removeView(views.get(position));
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        // TODO Auto-generated method stub
        View view = views.get(position);
        container.addView(view);
        if(position==2){
            Button btn = (Button) view.findViewById(R.id.pager_button);
            btn.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) {
                    Toast.makeText(v.getContext(), "點擊了按鈕", Toast.LENGTH_LONG).show();
                }
            });
        }
        return views.get(position);
    }
}

xml的編寫，需要完整的包名，

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.myviewpager.MainActivity" >
<android.support.v4.view.ViewPager
    android:id="@+id/viewpager"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</android.support.v4.view.ViewPager>

</RelativeLayout>

此外，每個頁面都是一個xml，比如：

<TextView 
        android:id="@+id/pager_text"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"
        android:text="第二個界面"/>

主活動：

public class MainActivity extends Activity {
    private ViewPager viewpager;
    private List<View> views;
    private LayoutInflater mInflater;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        viewpager = (ViewPager) findViewById(R.id.viewpager);
        views = new ArrayList<View>();
        mInflater = getLayoutInflater();
        View view1 = mInflater.inflate(R.layout.viewpager_item1, null);
        View view2 = mInflater.inflate(R.layout.viewpager_item2, null);
        View view3 = mInflater.inflate(R.layout.viewpager_item3, null);
        views.add(view1);
        views.add(view2);
        views.add(view3);
        ViewPagerAdapter myPager=new ViewPagerAdapter(views);
        viewpager.setAdapter(myPager);
    }