Android--下拉框

一. 实现效果图如下

　　Android 中的下拉框为Spinner 组件,其效果图如上图片

二. 实现代码

　　布局代码如下

<?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="match_parent"
    android:orientation="vertical" >

    <Spinner
        android:id="@+id/ddlCity"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

　　设置数据源

public class MainActivity extends Activity {
    private String[] items=new String[]{"北京","上海","广州","长沙"};
    private Animation myAnimation=null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ArrayAdapter<String> source=new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, items);

        Spinner ddlCity=(Spinner)findViewById(R.id.ddlCity);
        ddlCity.setAdapter(source);

        ddlCity.setOnItemSelectedListener(new Spinner.OnItemSelectedListener(){

            @Override
            public void onItemSelected(AdapterView<?> arg0, View arg1,
                    int arg2, long arg3) {
                new AlertDialog.Builder(MainActivity.this)
                .setTitle("提示")
                .setMessage("您选择的是"+items[arg2])
                .setPositiveButton("确定", null)
                .show();
            }

            @Override
            public void onNothingSelected(AdapterView<?> arg0) {

            }

        });
    }
}

数据源设置代码

　　Spinner的数据源使用ArrayAdapter

ArrayAdapter<String> source=new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, items);

　　这里需要制定下拉框Item的布局文件,这里选用系统中自带的布局文件