Android项目常用控件之ListView

最新推荐文章于 2024-08-04 17:25:58 发布

原创最新推荐文章于 2024-08-04 17:25:58 发布 · 352 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#android #BaseAdapter #ListView #控件

Android 专栏收录该内容

18 篇文章

订阅专栏

本文介绍如何在Android应用中使用ListView展示列表数据。通过定义布局文件和编写Activity代码，结合自定义适配器实现数据填充。适合初学者学习。

在Android项目中我们经常会用到ListView来展示相关内容

首先看下实现后的效果图：

在布局文件activity_main.xml中定义一个ListView控件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ListView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"></ListView>

</RelativeLayout>

在布局文件list_item.xml中填充ListView控件的itm

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <ImageView
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@mipmap/ic_launcher" />

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_centerVertical="true"
        android:text="安卓" />

</RelativeLayout>

Activity代码：

import android.app.Activity;
import android.os.Bundle;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MainActivity extends Activity {

    private ListView mListView;
    private MyListViewAdapter mAdapter;
    private List<Map<String, Object>> list;

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

        mListView = (ListView) findViewById(R.id.list);
        list = getData();
        mAdapter = new MyListViewAdapter(this, list);
        mListView.setAdapter(mAdapter);
    }

    private List<Map<String, Object>> getData() {
        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
        Map<String, Object> map;
        for (int i = 0; i < 10; i++) {
            map = new HashMap<String, Object>();
            map.put("img", R.mipmap.ic_launcher);
            map.put("title", "android");
            list.add(map);
        }
        return list;
    }


}

创建自定义适配器MyListViewAdapter继承BaseAdapter

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.List;
import java.util.Map;


public class MyListViewAdapter extends BaseAdapter {

    private LayoutInflater inflater;
    private List<Map<String, Object>> list;

    public MyListViewAdapter(Context context, List<Map<String, Object>> list) {
        this.list = list;
        this.inflater = LayoutInflater.from(context);
    }

    //获取数目中的条目数
    @Override
    public int getCount() {
        return list == null ? 0 : list.size();
    }

    //数据集中与指定索引对应的数据项
    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

    //列表中与指定索引对应的行id
    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            //加载布局为一个视图
            convertView = inflater.inflate(R.layout.list_item, null);
            holder = new ViewHolder();

            holder.mImageView = (ImageView) convertView.findViewById(R.id.image);
            holder.mTextView = (TextView) convertView.findViewById(R.id.text);

            convertView.setTag(holder);
        } else {

            holder = (ViewHolder) convertView.getTag();
        }
        holder.mTextView.setText((String) list.get(position).get("title"));
        return convertView;
    }

    public class ViewHolder {

        private ImageView mImageView;
        private TextView mTextView;

    }
}