ANDROID_MARS学习笔记_S02_001_Spinner

1.strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">S02_E01_SpinnerEtc</string>
    <string name="hello_world">Hello world!</string>
    <string name="action_settings">Settings</string>

    <string-array name="planets">
        <item>地球</item>
        <item>火星</item>
        <item>水星</item>
        <item>木星</item>
    </string-array>
</resources>

2.activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.s02_e01_spinneretc.MainActivity" >

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

</RelativeLayout>

3.item.xml自定义下拉项用

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:id="@+id/textViewId"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    />
</LinearLayout>

4.java

package com.example.s02_e01_spinneretc;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;

@SuppressLint("NewApi")
public class MainActivity extends ActionBarActivity implements OnItemSelectedListener{

    private Spinner mSpinner;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mSpinner = (Spinner) findViewById(R.id.mSpinner);
        // Create an ArrayAdapter using the string array and a default spinner layout
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.planets, 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
        mSpinner.setAdapter(adapter);
        mSpinner.setPrompt("测试");
        mSpinner.setOnItemSelectedListener(this);
    }

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

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position,
            long id) {
        System.out.println(parent.getItemAtPosition(position));
        
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {
        System.out.println(parent);
        
    }
}

5.自定义下拉源

package mars.spinner;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.AdapterView.OnItemSelectedListener;

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    //声明Spinner对象
    private Spinner spinner = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        //通过ID，得到Spinner对象
        spinner = (Spinner) findViewById(R.id.spinnerId);
        List<String> list = new ArrayList<String>();
        list.add("test1");
        list.add("test2");
        //调用ArrayAdapter的构造函数来创建ArrayAdapter对象
        //第一个参数是指上下文对象
        //第二个参数指定了下拉菜单当中每一个条目的样式
        //第三个参数指定了TextView控件的ID
        //第四个参数为整个列表提供数据
        ArrayAdapter adapter = new ArrayAdapter(this,R.layout.item,R.id.textViewId,list);
        //通过createFromResource方法创建一个ArrayAdapter对象
        //第一个参数是指上下文对象
        //第二参数引用了在strings.xml文件当中定义的String数组
        //第三个参数是用来指定Spinner的样式，是一个布局文件ID，该布局文件由Android系统提供，也可替换为自己定义的布局文件
        /*ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
                this, R.array.planets_array,
                android.R.layout.simple_spinner_item);
*/        //设置Spinner当中每个条目的样式，同样是引用一个Android系统提供的布局文件
        //adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        
        spinner.setAdapter(adapter);
        spinner.setPrompt("测试");
        //为spinner对象绑定监听器
        spinner.setOnItemSelectedListener(new SpinnerOnSelectedListener());
    }
    //这个监听器主要用来监听用户选择列表的动作
    class SpinnerOnSelectedListener implements OnItemSelectedListener{
        
        //当用户选定了一个条目时，就会调用该方法
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int position,
                long id) {
            String selected = adapterView.getItemAtPosition(position).toString();
            System.out.println(selected);
        }

        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {
            // TODO Auto-generated method stub
            System.out.println("nothingSelected");
        }
        
    }
}