ScrollView中的ListView潜在的解决方法

Question

我已就此事完成了所有研究.我知道Google认为这是毫无意义的,开发人员知道事实并非如此.我也知道没有已知的解决方法,但我知道我接近制作一个.用户DougW发布了此代码:

public class Utility {
    public static void setListViewHeightBasedOnChildren(ListView listView) {
        ListAdapter listAdapter = listView.getAdapter(); 
        if (listAdapter == null) {
            // pre-condition
            return;
        }

        int totalHeight = 0;
        for (int i = 0; i < listAdapter.getCount(); i++) {
            View listItem = listAdapter.getView(i, null, listView);
            listItem.measure(0, 0);
            totalHeight += listItem.getMeasuredHeight();
        }

        ViewGroup.LayoutParams params = listView.getLayoutParams();
        params.height = totalHeight + (listView.getDividerHeight() * (listAdapter.getCount() - 1));
        listView.setLayoutParams(params);
    }
}

几乎完成了我的工作.但是当我尝试它时,我在listItem.measure(0,0)行得到一个NullPointer异常.listItem本身已初始化,但该方法仍会抛出异常.请告诉我如何解决这个问题.

这是我的代码:

public class ExpenseReportsActivity extends Activity {

    private ListView lvReports;
    private ExpenseReportListAdapter adapter;
    private Button btnSend;
    private Button btnCancel;

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

        lvReports = (ListView)findViewById(R.id.lv_reports);
        lvReports.setBackgroundResource(R.drawable.shape_expense_report_list);

        ColorDrawable cd = new ColorDrawable(0xFFffffff);
        lvReports.setDivider(cd);
        lvReports.setDividerHeight(1);

        adapter = new ExpenseReportListAdapter(this);
        lvReports.setAdapter(adapter);

        int totalHeight = 0;
        for (int i = 0; i < adapter.getCount(); i++) {
            View listItem = adapter.getView(i, null, lvReports);
            listItem.measure(0, 0);
            totalHeight += listItem.getMeasuredHeight();
        }

        ViewGroup.LayoutParams params = lvReports.getLayoutParams();
        params.height = totalHeight + (lvReports.getDividerHeight() * (adapter.getCount() - 1));
        lvReports.setLayoutParams(params);
    }
}

我正在处理的另一个解决方法是使用我的自定义视图的onWindowFocusChanged方法.它告诉视图的精确高度.问题是当我仍在我的Activiy的onCreate方法中时,事件不会被触发,也不会在我的Activity的onWindowFocusChanged方法中触发.我尝试了一个自定义事件,但它从未触发过(它放在我的自定义视图的onWindowFocusChanged方法中,并且监听器在我的Activity的onWindowFocusChanged方法中).

Answer 1

好的,只要我满足您的需求,我想你可能只是使用这个ListView.addFooterView(View v)方法:

http://developer.android.com/reference/android/widget/ListView.html#addFooterView(android.view.View)

它允许您将所有列表项+"几个按钮"页脚作为单个块滚动.

所以代码应该是这样的:

import android.os.Bundle;
import android.view.LayoutInflater;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;

public class YourActivity extends ListActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        LayoutInflater factory = getLayoutInflater();
        LinearLayout footer = 
            (LinearLayout) factory.inflate(R.layout.your_a_few_buttons_footer, null);

        getListView().addFooterView(footer);

        String[] array = new String[50];
        for (int i = 0; i < 50;) { array[i] = "LoremIpsum " + (++i); }

        setListAdapter(
            new ArrayAdapter<String>(this, R.layout.list_item, array)
        );
    }   
}

注意,文档说addFooterView()应该在之前调用setListAdapter().

更新:View在列表顶部添加一个使用ListView.addHeaderView(View v).请注意,例如,LinearLayout也是一个View.因此,您可以将任何您想要的内容作为页眉或页脚放置,并且它将与列表一起滚动为不可分割的块.