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yayun0516 · 更新于 2018-11-28 11:00:43

Android 用的最多的,也最难用的应该就是 ListView 了,下面我们研究一下它的用法。

一、最简单的 ListView

我们简单介绍一下 ListView 的最简单用法,不使用布局文件:

package org.lxh.demo;

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

public class MainActivity extends Activity {
    private String[] arrays = { "Sunday", "Monday", "Tuesday", "Wednesday",
            "Thursday", "Friday", "Saturday" };
    private ListView listView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        listView = new ListView(this);
        listView.setAdapter(new ArrayAdapter<String>(this,
                android.R.layout.simple_expandable_list_item_1, arrays));//利用ArrayAdapter对数据进行包装
        super.setContentView(listView);//将ListView设置为显示界面
    }

}

运行实例如下:

二、结合 ArrayAdapter 实现较复杂的 ListView

1.main.xml 代码:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
    <ListView
        android:id="@+id/list_view"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" /></LinearLayout>

2.fruit_item.xml 代码:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <ImageView
        android:id="@+id/fruit_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/fruit_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginLeft="10sp" />
</LinearLayout>

3.Fruit.java 代码如下:

package org.lxh.demo;

public class Fruit {
    private String name;
    private int imageId;

    public Fruit(String name, int imageId) {
        this.name = name;
        this.imageId = imageId;
    }

    public String getName() {
        return name;
    }

    public int getImageId() {
        return imageId;
    }
}

4.集成 ArrayAdapter 的 FruitAdapter.java 代码如下:

package org.lxh.demo;

import java.util.List;

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

public class FruitAdapter extends ArrayAdapter<Fruit> {
    private int resourceId;

    public FruitAdapter(Context context, int textViewResourceId,
            List<Fruit> objects) {
        super(context, textViewResourceId, objects);
        resourceId = textViewResourceId;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Fruit fruit = getItem(position);
        View view;
        ViewHolder viewHolder;
        if (convertView == null) {
            view = LayoutInflater.from(getContext()).inflate(resourceId, null);
            viewHolder = new ViewHolder();
            viewHolder.fruitImage = (ImageView) view
                    .findViewById(R.id.fruit_image);
            viewHolder.fruitName = (TextView) view
                    .findViewById(R.id.fruit_name);
            view.setTag(viewHolder);
        } else {
            view = convertView;
            viewHolder = (ViewHolder) view.getTag();
        }

        viewHolder.fruitImage.setImageResource(fruit.getImageId());
        viewHolder.fruitName.setText(fruit.getName());
        return view;

    }

    class ViewHolder {
        ImageView fruitImage;
        TextView fruitName;
    }

}

5.MainActivity.java 代码如下:

package org.lxh.demo;

import java.util.ArrayList;
import java.util.List;

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

public class Hello extends Activity {
    private List<Fruit> fruitList = new ArrayList<Fruit>();

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState); // 生命周期方法
        super.setContentView(R.layout.main); // 设置要使用的布局管理器
        initFruits();
        FruitAdapter adapter = new FruitAdapter(Hello.this,
                R.layout.fruit_item, fruitList);
        ListView listView = (ListView) findViewById(R.id.list_view);
        listView.setAdapter(adapter);

    }

    private void initFruits() {
        Fruit appleFruit = new Fruit("Apple", R.drawable.apple_pic);
        fruitList.add(appleFruit);
        Fruit bananaFruit = new Fruit("Banana", R.drawable.banana_pic);
        fruitList.add(bananaFruit);
        Fruit orangeFruit = new Fruit("Orange", R.drawable.orange_pic);
        fruitList.add(orangeFruit);
        Fruit waterFruit = new Fruit("Apple", R.drawable.watermelon_pic);
        fruitList.add(waterFruit);

    }
}

运行实例如下:

三、结合上下文菜单实现单项的删除

修改 MainActivity.java 程序如下:


package org.lxh.demo;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.widget.ListView;
import android.widget.AdapterView.AdapterContextMenuInfo;

public class Hello extends Activity {
    private List<Fruit> fruitList = new ArrayList<Fruit>();
    FruitAdapter adapter;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState); // 生命周期方法
        super.setContentView(R.layout.main); // 设置要使用的布局管理器
        initFruits();
        adapter = new FruitAdapter(Hello.this, R.layout.fruit_item, fruitList);
        ListView listView = (ListView) findViewById(R.id.list_view);
        listView.setAdapter(adapter);
        super.registerForContextMenu(listView);//注册上下文菜单

    }

    @Override
    public void onCreateContextMenu(ContextMenu menu, View v,// 创建菜单项
            ContextMenuInfo menuInfo) {

        super.onCreateContextMenu(menu, v, menuInfo);
        menu.setHeaderTitle("选择操作");
        menu.add(Menu.NONE, Menu.FIRST + 1, 1, "删除");
        menu.add(Menu.NONE, Menu.FIRST + 2, 2, "取消");
    }

    @Override
    public boolean onContextItemSelected(MenuItem item) {// 选择监听
        AdapterContextMenuInfo acmiRef = (AdapterContextMenuInfo) item
                .getMenuInfo();// 用来获取item信息哎,重要
        int removeIndex = acmiRef.position;
        switch (item.getItemId()) {
        case Menu.FIRST + 1:
            fruitList.remove(removeIndex);
            adapter.notifyDataSetChanged();// 删除后刷新ListView

            break;
        case Menu.FIRST + 2:

            break;

        default:
            break;
        }
        return false;
    }

    private void initFruits() {
        Fruit appleFruit = new Fruit("Apple", R.drawable.apple_pic);
        fruitList.add(appleFruit);
        Fruit bananaFruit = new Fruit("Banana", R.drawable.banana_pic);
        fruitList.add(bananaFruit);
        Fruit orangeFruit = new Fruit("Orange", R.drawable.orange_pic);
        fruitList.add(orangeFruit);
        Fruit waterFruit = new Fruit("Apple", R.drawable.watermelon_pic);
        fruitList.add(waterFruit);

    }
}

运行实例:

选择删除后:

总结

  1. super.registerForContextMenu(listView);//注册上下文菜单
  2. adapter.notifyDataSetChanged();// 删除后刷新 ListView
  3. AdapterContextMenuInfo acmiRef = (AdapterContextMenuInfo) item.getMenuInfo();// 用来获取当前 item 信息,重要 int removeIndex = acmiRef.position;//获取点击位置的坐标