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
阿新 • • 發佈:2019-01-07
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: