1. 程式人生 > >定製ListView的介面(使用自定義的列表項佈局,一邊顯示水果圖片,一邊顯示水果文字)以及ListView的點選事件

定製ListView的介面(使用自定義的列表項佈局,一邊顯示水果圖片,一邊顯示水果文字)以及ListView的點選事件

只能顯示一段文字的ListView實在是太過單調,我們現在就來對ListView的介面進行定製,讓它可以顯示更加豐富的內容。

首先,我們需要準備好一組水果圖片,分別對應上面提供的每一種水果,待會我們要讓這些水果名稱的旁邊都有一個圖樣。

 

接著定義一個實體類,作為ListView介面卡的適配型別。新建類Fruit,程式碼如下:

package com.example.administrator.activitydemo;

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類中只有兩個欄位,name表示水果的名字,imageId表示水果對應圖片的資源id。

然後需要為ListView的子項指定一個我們自定義的佈局,在layout目錄下新建fruit_item.xml,程式碼如下:

<?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="wrap_content">

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

    <TextView
        android:id="@+id/tv_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="10dp" />
    
</LinearLayout>

在這個佈局中,我們定義了一個ImageView用於顯示水果的圖片,又定義了一個TextView用於顯示水果的名稱,並讓TextView在垂直方向上居中顯示。

接下來需要建立一個自定義的介面卡,這個介面卡繼承自ArrayAdapter,並將泛型指定為Fruit類。新建FruitAdapter,程式碼如下所示:

package com.example.administrator.activitydemo;

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;

public class FruitAdapter extends ArrayAdapter<Fruit> {

    private int resourceId;
    private List<Fruit> list;

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


    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Fruit fruit = list.get(position);//獲取當前項的Fruit例項
        View view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
        ImageView iv_name = (ImageView) view.findViewById(R.id.iv_name);//初始化圖片
        TextView tv_name = (TextView) view.findViewById(R.id.tv_name);//初始化文字
        iv_name.setImageResource(fruit.getImageId());//為ImageView設定圖片
        tv_name.setText("" + fruit.getName());//為TextView設定文字
        return view;
    }
}

FruitAdapter重寫了父類的一組建構函式,用於將上下文、ListView子項佈局的id和資料都傳遞進來。另外又重寫了getView()方法,這個方法在每個子項被滾動到螢幕內的時候會被呼叫。在getView()方法中,首先通過get()方法獲得到當前項的Fruit例項,然後使用LayoutInflater來為這個子項載入我們傳入的佈局。

MainActivity.java程式碼:

package com.example.administrator.activitydemo;

import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

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

public class MainActivity extends AppCompatActivity {
    private ListView listView;
    private String[] data = {"Apple", "Banana", "Orange", "Watermelon",
            "Pear", "Grape", "Pineapple", "Strawberry", "Cherry", "Mango",
            "Apple", "Banana", "Orange", "Watermelon",
            "Pear", "Grape", "Pineapple", "Strawberry", "Cherry", "Mango"
    };
    private int[] res = {R.drawable.apple, R.drawable.banana, R.drawable.orange, R.drawable.watermelon,
            R.drawable.pear, R.drawable.grape, R.drawable.pineapple, R.drawable.strawberry, R.drawable.cherry, R.drawable.mango,
            R.drawable.apple, R.drawable.banana, R.drawable.orange, R.drawable.watermelon,
            R.drawable.pear, R.drawable.grape, R.drawable.pineapple, R.drawable.strawberry, R.drawable.cherry, R.drawable.mango};
    private List<Fruit> fruitList;


    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();//初始化UI控制元件
        initData();//初始化資料
    }


    private void initView() {
        listView = (ListView) findViewById(R.id.listView);
    }

    private void initData() {
        initFruits();//初始化水果資料
        FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.fruit_item, fruitList);
        listView.setAdapter(adapter);
    }

    private void initFruits() {
        fruitList = new ArrayList<>();
        for (int i = 0; i < data.length; i++) {
            Fruit fruit = new Fruit(data[i], res[i]);
            fruitList.add(fruit);
        }
    }


}


執行程式,效果圖:

是不是稍微好看了一點。

ListView的點選事件:

修改MainActivity.java中的程式碼:

package com.example.administrator.activitydemo;

import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

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

public class MainActivity extends AppCompatActivity {
    private ListView listView;
    private String[] data = {"Apple", "Banana", "Orange", "Watermelon",
            "Pear", "Grape", "Pineapple", "Strawberry", "Cherry", "Mango",
            "Apple", "Banana", "Orange", "Watermelon",
            "Pear", "Grape", "Pineapple", "Strawberry", "Cherry", "Mango"
    };
    private int[] res = {R.drawable.apple, R.drawable.banana, R.drawable.orange, R.drawable.watermelon,
            R.drawable.pear, R.drawable.grape, R.drawable.pineapple, R.drawable.strawberry, R.drawable.cherry, R.drawable.mango,
            R.drawable.apple, R.drawable.banana, R.drawable.orange, R.drawable.watermelon,
            R.drawable.pear, R.drawable.grape, R.drawable.pineapple, R.drawable.strawberry, R.drawable.cherry, R.drawable.mango};
    private List<Fruit> fruitList;


    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();//初始化UI控制元件
        initData();//初始化資料
    }


    private void initView() {
        listView = (ListView) findViewById(R.id.listView);
    }

    private void initData() {
        initFruits();//初始化水果資料
        FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.fruit_item, fruitList);
        listView.setAdapter(adapter);
    }

    private void initFruits() {
        fruitList = new ArrayList<>();
        for (int i = 0; i < data.length; i++) {
            Fruit fruit = new Fruit(data[i], res[i]);
            fruitList.add(fruit);
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Fruit fruit = fruitList.get(position);
                Toast.makeText(MainActivity.this, "" + fruit.getName(), Toast.LENGTH_SHORT).show();
            }
        });
    }
}


效果圖: