面试的几个小问题？

1：ScrollView和ListView的？

有时候项目里面需要ScrollView嵌套ListView,但是正常下ListView只会显示一行多一点，解决方法就是填充ListView数据后

重新计算ListView的高度，这里有两种方法来实现。

***（1）第一种方法：重写ListView

package com.jwzhangjie.test;

import android.content.Context;

import android.util.AttributeSet;

import android.widget.ListView;

public class MyListView extends ListView{

public MyListView(Context context) {

super(context);

}

public MyListView(Context context, AttributeSet attrs) {

super(context, attrs);

}

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2,

MeasureSpec.AT_MOST);

super.onMeasure(widthMeasureSpec, expandSpec);

}

}

*****（2）第二种方法：添加完数据后计算ListView中所有Item的高度和间隔线的高度然后重新设置ListView的高度

public void setListViewHeightBasedOnChildren(ListView listView) {

ListAdapter listAdapter = listView.getAdapter();

if (listAdapter == null)

return;

if (listAdapter.getCount() <= 1)

return;

int totalHeight = 0;

View view = null;

for (int i = 0; i < listAdapter.getCount(); i++) {

view = listAdapter.getView(i, null, listView);

view.measure(0,0);

totalHeight += view.getMeasuredHeight();

}

ViewGroup.LayoutParams params = listView.getLayoutParams();

params.height = totalHeight

+ (listView.getDividerHeight() * (listAdapter.getCount() - 1));

listView.setLayoutParams(params);

listView.requestLayout();

}

设置完数据后，调用setListViewHeightBasedOnChildren(listview);