android - 我想测量 ListView 的高度(getHight() = 0)

Question

我不能自己决定任务会问

我想测量 ListView 的高度。无法捕捉到渲染 ListView 的时刻 (rssListView.getHight(); = 0 )

public class RSSactivity extends Activity {

    public static RssItem selectedRssItem = null;
    String feedUrl = "";
    ListView rssListView = null;
    ArrayList<RssItem> rssItems = new ArrayList<RssItem>();
    ArrayAdapter<RssItem> aa = null;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        rssListView = (ListView) findViewById(R.id.rssListView);
        aa = new ArrayAdapter<RssItem>(this, R.layout.list_item, rssItems);
        rssListView.setAdapter(aa); 
        feedUrl = rssURLTV.getText().toString();
        refressRssList();
        rssListView.getWidth(); // = 0 ,    
    }

    private void refressRssList() {

        ArrayList<RssItem> newItems = RssItem.getRssItems(feedUrl);
        rssItems.clear();
        rssItems.addAll(newItems);
        aa.notifyDataSetChanged();

    }

}

目标是计算 ListView 屏幕中的项目数量

Answer 1

在onCreate中:

rssListView.getViewTreeObserver().addOnGlobalLayoutListener(
    new ViewTreeObserver.OnGlobalLayoutListener() {
      @Override
      public void onGlobalLayout() {
        // If you need this to be called again, then run again addOnGlobalLayoutListener.
        mainPanel.getViewTreeObserver().removeGlobalOnLayoutListener(this);
        rssListView.getWidth(); // It's available here.
      }
    });