Android應用開發學習之列表選擇框

 

本文我們來看列表選擇框的實現。程序運行效果如下圖所示：

 

主佈局文件main.xml內容如下所示：

 

<PRE class=html name="code"><?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/prompt" />
    <Spinner 
    	android:entries="@array/brands"
   	 	android:layout_height="wrap_content" 
   		android:layout_width="wrap_content" 
    	android:id="@+id/spinner"/>
<Button 
android:text="提交" 
    		android:id="@+id/button" 
    		android:layout_width="wrap_content" 
    		android:layout_height="wrap_content"/>  
</LinearLayout>
</PRE><BR>
<PRE></PRE>
<P>Spinner標記指定瞭列表選擇框，列表選擇框的內容是由android:entries屬性指定的，即數組資源@array/brands，我們將該數組定義在一個單獨的資源文件BrandArray.xml中，其定義如下：</P>
<PRE class=html name="code"><?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="brands">
    	<item>蘋果</item>
    	<item>三星</item>
    	<item>HTC</item>
    	<item>諾基亞</item>
    	<item>聯想</item>
    	<item>華為</item>
    	<item>其它</item>
    </string-array>
</resources>
</PRE>
<P>&nbsp;</P>
<P><SPAN style="FONT-SIZE: 14px">最後，編寫主<SPAN style="FONT-FAMILY: Calibri">Activity</SPAN>文件，響應用戶的操作，其內容如下：</SPAN><BR>
</P>
<P><SPAN style="FONT-SIZE: 14px"></SPAN>&nbsp;</P>
<SPAN style="COLOR: teal"></SPAN><PRE class=html name="code">package com.liuhaoyu;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.Spinner;
import android.widget.Toast;
import android.widget.AdapterView.OnItemSelectedListener;

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        final Spinner spinner = (Spinner) findViewById(R.id.spinner);
        
        spinner.setOnItemSelectedListener(new OnItemSelectedListener() {

        	@Override
			public void onItemSelected(AdapterView<?> parent, View arg1,
					int pos, long id) {
				String result = parent.getItemAtPosition(pos).toString();
				Log.i("選擇結果是：", result);
			}

			@Override
			public void onNothingSelected(AdapterView<?> arg0) {
			}
			
		});
        
        Button button = (Button) findViewById(R.id.button);

		button.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				Toast.makeText(MainActivity.this,
						"您選擇的品牌是：" + spinner.getSelectedItem().toString(),
						Toast.LENGTH_SHORT).show();
			}
		});
    }
}</PRE>
<P align=left><BR>
<SPAN style="COLOR: black">&nbsp;</SPAN></P>
<P><SPAN style="COLOR: black">以上我們是通過在佈局文件中通過數組資源直接為列表選擇框指定列表內容，如果不在佈局文件中指定，也可以通過使用適配器的方式為其指定列表內容。下面我們來看一個例子，其運行效果如下：</SPAN></P>
<P><IMG alt="" src="https://img.blog.csdn.net/20130801163255843?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvbGl1aGFveXV0eg==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/SouthEast"></P>
<P><SPAN style="FONT-SIZE: 14px">主佈局文件<SPAN style="FONT-FAMILY: Calibri">main.xml</SPAN>內容如下：</SPAN></P>
<SPAN style="COLOR: teal"></SPAN><PRE class=html name="code"><?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/prompt" />
    <Spinner 
   	 	android:layout_height="wrap_content" 
   		android:layout_width="wrap_content" 
    	android:id="@+id/spinner"/>
    <Button android:text="提交" 
    	android:id="@+id/button" 
    	android:layout_width="wrap_content" 
    	android:layout_height="wrap_content"/>  
</LinearLayout></PRE>
<P align=left><BR>
<SPAN style="COLOR: teal">主</SPAN><SPAN style="COLOR: teal">Activity</SPAN><SPAN style="COLOR: teal">文件內容如下：</SPAN></P>
<SPAN style="FONT-FAMILY: Calibri; FONT-SIZE: 14px"></SPAN><PRE class=java name="code"><?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/prompt" />
    <Spinner 
   	 	android:layout_height="wrap_content" 
   		android:layout_width="wrap_content" 
    	android:id="@+id/spinner"/>
    <Button android:text="提交" 
    	android:id="@+id/button" 
    	android:layout_width="wrap_content" 
    	android:layout_height="wrap_content"/>  
</LinearLayout>
主Activity文件內容如下：
package com.liuhaoyu;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Spinner;
import android.widget.Toast;

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        final Spinner spinner = (Spinner) findViewById(R.id.spinner);
        
        // 通過在代碼中定義數組來創建適配器.
        String[] brand=new String[]{"蘋果","三星","HTC","諾基亞","聯想","華為","其它"};
		ArrayAdapter<String> adapter=new ArrayAdapter<String>(this,android.R.layout.simple_spinner_dropdown_item,brand);
		
 		// 也可以使用數組資源來創建適配器，而不是象上面那樣在代碼中定義 數組。 
//		ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
//				this, R.array.brands,android.R.layout.simple_spinner_dropdown_item);

		spinner.setAdapter(adapter); // 將適配器與選擇列表框關聯		
        
        spinner.setOnItemSelectedListener(new OnItemSelectedListener() {

        	@Override
			public void onItemSelected(AdapterView<?> parent, View arg1, int pos, long id) {
				String result = parent.getItemAtPosition(pos).toString();
				Log.i("選擇結果是：", result);
			}

			@Override
			public void onNothingSelected(AdapterView<?> arg0) {
			}
			
		});
        
        Button button = (Button) findViewById(R.id.button);

		button.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				Toast.makeText(MainActivity.this,
						"您選擇的品牌是：" + spinner.getSelectedItem().toString(),
						Toast.LENGTH_SHORT).show();
			}
		});
    }
    
}</PRE>
<P>&nbsp;</P>