是否可以在ViewPagerAdapter外部设置文本或背景颜色？

Question

在ViewPagerAdapter.class我有2个layout（whereami.xml和mapview.xml），并使用LayoutInflater来为instantiateItem()内的每个视图充气，通常我应该在InstantiateItem instantiateItem()内设置所有内容（根据xml的TextView，ImageView等instantiateItem() 。 但就我而言，我确实需要在ViewPagerActivity的onCreate()处设置setText或Background颜色，以扩展MapActivity

那么，是否有必要在onCreate()设置它们？

PS我尝试调试程序，发现过程不会叫instantiateItem()直到它走出的onCreate()方法。 因此，由于View为Null，因此每次创建setText时，View都不会创建，并且编程强制关闭。

ViewPagerActivity

public class ViewPagerActivity extends MapActivity {
    private ViewPagerAdapter adapter;
    private ViewPager pager;

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

        adapter = new ViewPagerAdapter(this);
        pager = (ViewPager) findViewById(R.id.viewpager);
        TitlePageIndicator indicator = (TitlePageIndicator) findViewById(R.id.indicator);
        pager.setAdapter(adapter);
        indicator.setViewPager(pager);


        //LinearLayout bgcolor = (LinearLayout)findViewById(R.id.mainlayout);
        //bgcolor.setBackgroundColor(Color.Black);
        //TextView text1 = (TextView)findViewById(R.id.text1);
        //text1.setText("somevalue");

    }


}

ViewPagerAdapter

public class ViewPagerAdapter extends PagerAdapter implements TitleProvider {
    private final Context context;
    private MapView mapView;
    private MapController mapController;
    private View view;

    public ViewPagerAdapter(Context context) {
    }

    private static String[] titles = new String[] { "Page1", "Map" };

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

        if (position == 0) {
            view = inflater.inflate(R.layout.whereami, null);
            ((ViewPager) pager).addView(view, 0);

        }
        if (position == 1) {
            view = inflater.inflate(R.layout.my_map_activity, null);
            ((ViewPager) pager).addView(view, 0);
            mapView = (MapView) view.findViewById(R.id.mapview);

            mapController = mapView.getController();
            mapController.setZoom(14);
        }

        return view;
    }

}

whereami.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/mainlayout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

<TextView
    android:id="@+id/text1"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="8dp"
    android:textSize="16sp" >
</TextView>
</LinearLayout>

Answer 1

如果您知道onCreate()的TextView中应该包含什么内容，为什么不通过适配器的构造函数传递它呢？

new ViewPagerAdapter(this, "TextToPass");

带有：

private String toDisplay;
public ViewPagerAdapter(Context context, String toDisplay) {
    this.toDispay = toDisplay;
}

和：

view = inflater.inflate(R.layout.whereami, null);
TextView textView = view.findViewById(R.id.text1);
textView.setText(toDisplay);