Android开发学习之路--UI之ListView

Posted 2020-06-13 东月之神

    这里再学习写android的ListView，其实我们都使用过ListView，就像手机的联系人，就是用的ListView了。下面就实现下简单的ListView吧，首先是xml文件中添加相关的代码：

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

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

</LinearLayout>

    然后在MainActivity代码中实现如下：

package com.example.jared.uilistview;

import android.os.Bundle;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class MainActivity extends AppCompatActivity {

    private String[] data = {"苹果", "香蕉", "梨子", "西瓜", "蓝莓", "葡萄", "橘子",
                             "甘蔗", "火龙果", "柚子", "荔枝", "猕猴桃"};
    private ListView listView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActionBar actionBar = getSupportActionBar();
        actionBar.hide();
        
        setContentView(R.layout.activity_main);

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(
          MainActivity.this, android.R.layout.simple_list_item_1, data);
        listView = (ListView)findViewById(R.id.list_view);
        listView.setAdapter(adapter);
    }
}

     这里定义了ArrayAdapter适配器，用来适配ListView，可以泛型编程，这里只用String，所以用这个倒是挺合适。

     运行代码如下：

    

    这里实现的最简单就是文字，下面在添加图片试试。

    首先新建fruit类，代码如下：

package com.example.jared.uilistview;

/**
 * Created by jared on 16/2/9.
 */
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;
    }
}

    Fruit类主要是提供一个名字和一张图片，所以提供了获取名字和imageid的接口。

    接着新建一个fruit.xml用来提供imageview和textview，当然还可以扩展，代码如下：

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

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

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

</LinearLayout>

    创建自定义适配器FruitAdapter，代码如下：

package com.example.jared.uilistview;

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;

import java.util.List;

/**
 * Created by jared on 16/2/9.
 */
public class FruitAdapter extends ArrayAdapter<Fruit> {
    private int resourceId;

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

    public View getView(int position, View convertView, ViewGroup parent) {
        Fruit fruit = getItem(position);
        View view = LayoutInflater.from(getContext()).inflate(resourceId, null);
        ImageView fruitImage = (ImageView)view.findViewById(R.id.fruit_image);
        TextView fruitName = (TextView)view.findViewById(R.id.fruit_name);
        fruitImage.setImageResource(fruit.getImageId());
        fruitName.setText(fruit.getName());
        return view;
    }
}

    最后修改MainActivity代码，如下所示：

package com.example.jared.uilistview;

import android.os.Bundle;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.widget.ListView;

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

public class MainActivity extends AppCompatActivity {

    private List<Fruit> fruitList = new ArrayList<Fruit>();
    private ListView listView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActionBar actionBar = getSupportActionBar();
        actionBar.hide();

        setContentView(R.layout.activity_main);
        initFruits();
        FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.fruit, fruitList);

        listView = (ListView)findViewById(R.id.list_view);
        listView.setAdapter(adapter);
    }

    private void initFruits() {
        Fruit apple = new Fruit("苹果", R.drawable.apple);
        fruitList.add(apple);
        Fruit banana = new Fruit("香蕉", R.drawable.banana);
        fruitList.add(banana);
        Fruit pear = new Fruit("梨子", R.drawable.pear);
        fruitList.add(pear);
        Fruit watermelon = new Fruit("西瓜", R.drawable.watermelon);
        fruitList.add(watermelon);
        Fruit grape = new Fruit("葡萄", R.drawable.grape);
        fruitList.add(grape);
        Fruit orange = new Fruit("橙子", R.drawable.orange);
        fruitList.add(orange);
        Fruit litchi = new Fruit("荔枝", R.drawable.litchi);
        fruitList.add(litchi);
        Fruit strawberry = new Fruit("草莓", R.drawable.strawberry);
        fruitList.add(strawberry);
        Fruit pineapple = new Fruit("菠萝", R.drawable.pineapple);
        fruitList.add(pineapple);
    }
}

    运行看效果如下：

    图片和文字都显示着了，那么怎么实现点击的效果呢？那下面就来学习下了。

    首先是在MainActivity中添加代码如下：

package com.example.jared.uilistview;

import android.os.Bundle;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;

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

public class MainActivity extends AppCompatActivity {

    private List<Fruit> fruitList = new ArrayList<Fruit>();
    private ListView listView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActionBar actionBar = getSupportActionBar();
        actionBar.hide();

        setContentView(R.layout.activity_main);
        initFruits();
        FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.fruit, fruitList);

        listView = (ListView)findViewById(R.id.list_view);
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Fruit fruit = fruitList.get(i);
                Toast.makeText(MainActivity.this, fruit.getName(), Toast.LENGTH_SHORT).show();
            }
        });
    }

    private void initFruits() {
        Fruit apple = new Fruit("苹果", R.drawable.apple);
        fruitList.add(apple);
        Fruit banana = new Fruit("香蕉", R.drawable.banana);
        fruitList.add(banana);
        Fruit pear = new Fruit("梨子", R.drawable.pear);
        fruitList.add(pear);
        Fruit watermelon = new Fruit("西瓜", R.drawable.watermelon);
        fruitList.add(watermelon);
        Fruit grape = new Fruit("葡萄", R.drawable.grape);
        fruitList.add(grape);
        Fruit orange = new Fruit("橙子", R.drawable.orange);
        fruitList.add(orange);
        Fruit litchi = new Fruit("荔枝", R.drawable.litchi);
        fruitList.add(litchi);
        Fruit strawberry = new Fruit("草莓", R.drawable.strawberry);
        fruitList.add(strawberry);
        Fruit pineapple = new Fruit("菠萝", R.drawable.pineapple);
        fruitList.add(pineapple);
    }
}

    这里添加了setOnItemClickListener方法，然后就类似于Button一样的。运行看下效果，如下：

    ViewList基本上就学习这些知识了。