Android动态计算ListView高度

最新推荐文章于 2021-05-25 18:10:31 发布

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本文介绍了如何在Android中动态计算ListView的高度，以优化UI显示和提高性能。通过解析内容和适配器数据，实现ListView在加载时准确适应其内容的高度。

1:上布局代码;

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.administrator.myapplication.MainActivity">

    <ListView
        android:id="@+id/lv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true" />
</RelativeLayout>

2：设置数据;

 ArrayList<String> datas = new ArrayList<>();
        for (int i = 0; i < 50; i++) {
            datas.add("测试数据" + i);
        }

        ListView listView = (ListView) findViewById(R.id.lv);
        listView.setAdapter(new MyBaseAdapter(datas));

3:适配器;

//适配器
    private class MyBaseAdapter extends BaseAdapter {

        private ArrayList<String> datas;

        private MyBaseAdapter(ArrayList<String> datas) {
            this.datas = datas;
        }

        @Override
        public int getCount() {
            return datas.size();
        }

        @Override
        public Object getItem(int position) {
            return null;
        }

        @Override
        public long getItemId(int position) {
            return 0;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            TextView textView = new TextView(MainActivity.this);
            textView.setText(datas.get(position));
            textView.setPadding(0, 40, 0, 40);
            textView.setGravity(Gravity.CENTER_HORIZONTAL);
            return textView;
        }
    }

3：关键的一步，在设置过适配器以后，调用以下方法为ListView设置高度;

public void setListViewHeightBasedOnChildren(ListView listView) {
        // 获取ListView对应的Adapter
        ListAdapter listAdapter = listView.getAdapter();
        if (listAdapter == null) {
            return;
        }
        int totalHeight = 0;
        for (int i = 0; i < listAdapter.getCount(); i++) {
            View listItem = listAdapter.getView(i, null, listView);
            //计算item的宽高
            listItem.measure(0, 0);
            //累计所有item的高度
            totalHeight += listItem.getMeasuredHeight();
        }
        ViewGroup.LayoutParams params = listView.getLayoutParams();
        params.height = totalHeight + (listView.getDividerHeight()) *(listAdapter.getCount()-1);
        listView.setLayoutParams(params);
    }