Android开发--Spinner控件的使用

我们经常会在Windows开发的过程中看到一个下拉菜单控件，在Android中也有相应的控件，它的名字叫Spinner，本文介绍Spinner的用法。

首先，下面的这张截图是实现的实例：

在第一行，你会看到一行说明“This is just Test！”，这个类似于标题，它的定义方法是spinner.setPrompt("This is just Test!");

下面的数据是引用资源，使用的是string数组，让我们来看下数组的定义：

   <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>

当用户点击选择Spinner的下拉选项时，会弹出相应的Toast说明，这就需要实现相应的监听功能

下面给出本程序的源代码：

public class Spinner_Activiy extends Activity {
	private Spinner spinner=null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_spinner__activiy);
		Spinner spinner = (Spinner) findViewById(R.id.planets_spinner);
		// Create an ArrayAdapter using the string array and a default spinner layout
		ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
		        R.array.planets_array, android.R.layout.simple_spinner_item);
		// Specify the layout to use when the list of choices appears
		adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
		// Apply the adapter to the spinner
		spinner.setAdapter(adapter);
		spinner.setPrompt("This is just Test!");
		spinner.setOnItemSelectedListener(new SpinnerActivity());
	}
	public class SpinnerActivity implements OnItemSelectedListener {
	   
	    
	    public void onItemSelected(AdapterView<?> parent, View view, 
	            int pos, long id) {
	        // An item was selected. You can retrieve the selected item using
	        // parent.getItemAtPosition(pos)
	    	Toast.makeText(Spinner_Activiy.this, "Your selection is "+parent.getItemAtPosition(pos).toString(), Toast.LENGTH_LONG).show();
	    }

	    public void onNothingSelected(AdapterView<?> parent) {
	        // Another interface callback
	    }
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.activity_spinner__activiy, menu);
		return true;
	}

}