关于获得ArrayAdapter对象的细节

在写一个 SlidingDrawer的Demo时，发现一个自己原来没有注意的问题。

首先贴上源代码。

 

package com.example.slidingdrawerproject;

import android.R.anim;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.res.Resources;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.SlidingDrawer;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ZoomControls;

public class SlidingDrawerActivity extends Activity {

    private SlidingDrawer drawer = null;
    private ListView listView = null;
    private ArrayAdapter<CharSequence> adapter = null;
    private TextView textView = null;
    private ZoomControls controls = null;
    private float curFontSize = 0;
    private String[] data = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        super.setContentView(R.layout.activity_sliding_drawer);
        drawer = (SlidingDrawer) super.findViewById(R.id.slidingdrawer);

        LinearLayout layout = (LinearLayout) super.findViewById(R.id.content);
        listView = new ListView(this);
 adapter = ArrayAdapter.createFromResource(this, R.array.citys, android.R.layout.simple_list_item_1); // Resources resources = getResources(); // data = resources.getStringArray(R.array.citys); // adapter = new ArrayAdapter<CharSequence>(this, // android.R.layout.simple_list_item_1, data);
        listView.setAdapter(adapter);
        layout.addView(listView, 2);


        drawer.setOnDrawerCloseListener(new SlidingDrawer.OnDrawerCloseListener() {

            @Override
            public void onDrawerClosed() {
                Toast.makeText(SlidingDrawerActivity.this, "关闭组件",
                        Toast.LENGTH_SHORT).show();
            }
        });
        drawer.setOnDrawerOpenListener(new SlidingDrawer.OnDrawerOpenListener() {

            @Override
            public void onDrawerOpened() {
                Toast.makeText(SlidingDrawerActivity.this, "打开组件",
                        Toast.LENGTH_SHORT).show();
            }
        });

        drawer.setOnDrawerScrollListener(new SlidingDrawer.OnDrawerScrollListener() {

            @Override
            public void onScrollStarted() {
                Toast.makeText(SlidingDrawerActivity.this, "滑动组件ing....",
                        Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onScrollEnded() {
                Toast.makeText(SlidingDrawerActivity.this, "滑动组件end",
                        Toast.LENGTH_SHORT).show();

            }
        });

        listView.setOnItemClickListener(new ListView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                Object obj = parent.getAdapter().getItem(position);
                if (obj instanceof String) {
                    String info = (String) obj;
                    Dialog dialog = new AlertDialog.Builder(
                            SlidingDrawerActivity.this).setTitle("info")
                            .setMessage(info).setIcon(R.drawable.ic_launcher)
                            .create();

                    dialog.show();
                }
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_sliding_drawer, menu);
        return true;
    }

}

 

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="citys">
        <item>北京</item>
        <item>南昌</item>
        <item>昆明</item>
        <item>九江</item>
        <!-- (云南过桥米线发源地) -->
        <item>蒙自</item>
        <item>深证</item>
        <item>东莞</item>
        <item>香港</item>
    </string-array>
</resources>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <SlidingDrawer
        android:id="@+id/slidingdrawer"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical"
        android:handle="@+id/handle"
        android:content="@+id/content"
        >
        <ImageView
            android:id="@+id/handle"
            android:src="@android:drawable/ic_lock_idle_alarm"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            />

        <LinearLayout
            android:id="@+id/content"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:orientation="vertical" >

            <TextView
                android:id="@+id/slid_txt"
                android:text="明天放假"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                />
            <ZoomControls
                android:id="@+id/slid_zoomCon"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                />

        </LinearLayout>
    </SlidingDrawer>

</LinearLayout>

效果图：

 

这是可以出现效果的。

在ArrayAdapter中的源代码中：是

adapter = ArrayAdapter.createFromResource(this, R.array.citys,
    android.R.layout.simple_list_item_1);

这个是没有问题的，查API文档，

 

public static ArrayAdapter<CharSequence> createFromResource (Context context, int textArrayResId, int textViewResId)

Since:  API Level 1

Creates a new ArrayAdapter from external resources. The content of the array is obtained through getTextArray(int).

Parameters

context	The application's environment.
textArrayResId	The identifier of the array to use as the data source.//xml中array的id
textViewResId	The identifier of the layout used to create views.//xml中layout的id

Returns

• An ArrayAdapter .

 

可是由于自己的粗心，把代码写成

adapter = new ArrayAdapter<CharSequence>(this,
                android.R.layout.simple_list_item_1,R.array.citys);

而且由于类型匹配，所以系统没有报错。

后来查过API

public ArrayAdapter (Context context, int resource, int textViewResourceId)

Since:  API Level 1

Constructor

Parameters

context	The current context.
resource	The resource ID for a layout file containing a layout to use when instantiating views.
textViewResourceId	The id of the TextView within the layout resource to be populated//TextView在layout中的id

所以自己错写的方法是不匹配的。

这里还有两种方法写这个adapter：首先看API文档

public ArrayAdapter (Context context, int textViewResourceId, T[] objects)

Since:  API Level 1

Constructor

Parameters

context	The current context.
textViewResourceId	The resource ID for a layout file containing a TextView to use when instantiating views.
objects	The objects to represent in the ListView.

①

将数据在代码中写成数组形式，

private String[] pro=new String[]{"北京","上海","广东","江西","云南","福建","海南","河南"};

adapter = new ArrayAdapter<CharSequence>(this,
                android.R.layout.simple_list_item_1, data);

②将xml中的资源通过resources的getStringArray（）方法转化为数组。

Resources resources = getResources();
        data = resources.getStringArray(R.array.citys);
        adapter = new ArrayAdapter<CharSequence>(this,
                android.R.layout.simple_list_item_1, data);

 

 

 

 

 

 

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