范例HelloSpinner

Android docs中的范例，简单翻译整理如下。

注：范例过程及相关代码有部分调整，请知晓。
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1、创建新项目，名称HelloSpinner；

2、修改res/layout/strings.xml，内容如下：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="planet_prompt">Choose a planet</string>
    <string-array name="planets_array">
        <item>Mercury</item>
        <item>Venus</item>
        <item>Earth</item>
        <item>Mars</item>
        <item>Jupiter</item>
        <item>Saturn</item>
        <item>Uranus</item>
        <item>Neptune</item>
    </string-array>
</resources>

3、修改res/layout/main.xml，内容如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:padding="10dip"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dip"
        android:text="@string/planet_prompt"
    />
    <Spinner 
        android:id="@+id/spinner"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:prompt="@string/planet_prompt"
    />
</LinearLayout>

3、增加类MyOnItemSelectedListener.java，类代码如下：

public class MyOnItemSelectedListener implements OnItemSelectedListener {

	public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
		Toast.makeText(parent.getContext(), "The planet is " + parent.getItemAtPosition(pos).toString(),
				Toast.LENGTH_LONG).show();
	}

	public void onNothingSelected(AdapterView<?> parent) {
		// Do nothing.
	}
}

4、修改HelloSpinner.java的onCreate方法，内容如下：

	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		Spinner spinner = (Spinner) findViewById(R.id.spinner);
		ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.planets_array,
				android.R.layout.simple_spinner_item);
		adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
		spinner.setAdapter(adapter);
		spinner.setOnItemSelectedListener(new MyOnItemSelectedListener());
	}

5、运行项目，即可看到运行效果，如下图所示：