Android之Spinner用法

一. 简单认识

Activity

package cn.lyj.android;import android.app.Activity;import android.content.Context;import android.content.SharedPreferences;import android.os.Bundle;import android.view.View;import android.widget.AdapterView;import android.widget.AdapterView.OnItemSelectedListener;import android.widget.ArrayAdapter;import android.widget.Spinner;import android.widget.TextView;import android.widget.Toast;public class AndroidUIActivity extends Activity {protected int mPos;protected String mSelection;protected ArrayAdapter<CharSequence> mAdapter;public static final int DEFAULT_POSITION = 2;public static final String PREFERENCES_FILE = "SpinnerPrefs";public static final String PROPERTY_DELIMITER = "=";public static final String POSITION_KEY = "Position";public static final String SELECTION_KEY = "Selection";public static final String POSITION_MARKER = POSITION_KEY+ PROPERTY_DELIMITER;public static final String SELECTION_MARKER = SELECTION_KEY+ PROPERTY_DELIMITER;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);Spinner spinner = (Spinner) findViewById(R.id.Spinner01);// 设置ArrayAdapterthis.mAdapter = ArrayAdapter.createFromResource(this, R.array.Planets,android.R.layout.simple_spinner_dropdown_item);spinner.setAdapter(this.mAdapter);// 选中触发事件，在窗口中央显示项目OnItemSelectedListener spinnerListener = new myOnItemSelectedListener(this, this.mAdapter);spinner.setOnItemSelectedListener(spinnerListener);}/** * 用户选中下拉列表中得一项 */public class myOnItemSelectedListener implements OnItemSelectedListener {ArrayAdapter<CharSequence> mLocalAdapter;Activity mLocalContext;// 构造方法public myOnItemSelectedListener(Activity c,ArrayAdapter<CharSequence> ad) {this.mLocalContext = c;this.mLocalAdapter = ad;}//When the user selects an item in the spinner, this method is invoked by the callback chainpublic void onItemSelected(AdapterView<?> parent, View v, int pos,long row) {//暂时没发现有什么用//AndroidUIActivity.this.mPos = pos;AndroidUIActivity.this.mSelection = parent.getItemAtPosition(pos).toString();TextView resultText = (TextView) findViewById(R.id.SpinnerResult);resultText.setText(AndroidUIActivity.this.mSelection);}//无用public void onNothingSelected(AdapterView<?> parent) {}}/* * Restores the current state of the spinner (which item is selected, and the value     * of that item). */@Overridepublic void onResume() {super.onResume();if (!readInstanceState(this))setInitialState();Spinner restoreSpinner = (Spinner) findViewById(R.id.Spinner01);restoreSpinner.setSelection(getSpinnerPosition());}/** * Read the previous state of the spinner from the preferences file */public boolean readInstanceState(Context c) {SharedPreferences p = c.getSharedPreferences(PREFERENCES_FILE,MODE_WORLD_READABLE);this.mPos = p.getInt(POSITION_KEY, AndroidUIActivity.DEFAULT_POSITION);this.mSelection = p.getString(SELECTION_KEY, "");return (p.contains(POSITION_KEY));}/* *Store the current state of the spinner (which item is selected, and the value of that item). */@Overridepublic void onPause() {super.onPause();if (!writeInstanceState(this)) {Toast.makeText(this, "Failed to write state!", Toast.LENGTH_LONG).show();}}/** * Write the application's current state to a properties repository. */public boolean writeInstanceState(Context c) {SharedPreferences p = c.getSharedPreferences(AndroidUIActivity.PREFERENCES_FILE, MODE_WORLD_READABLE);SharedPreferences.Editor e = p.edit();e.putInt(POSITION_KEY, this.mPos);e.putString(SELECTION_KEY, this.mSelection);return (e.commit());}/** * Sets the initial state of the spinner when the application is first run. */public void setInitialState() {this.mPos = DEFAULT_POSITION;}public int getSpinnerPosition() {return this.mPos;}public void setSpinnerPosition(int pos) {this.mPos = pos;}public String getSpinnerSelection() {return this.mSelection;}public void setSpinnerSelection(String selection) {this.mSelection = selection;}}

main.xml

<?xml version="1.0" encoding="utf-8"?><!--     Creates a Linear Layout View to contain the spinner --><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >    <!--        Creates a spinner widget called Spinner01, within the Linear Layout        The prompt text comes from the string "planet_prompt" in strings.xmlSpinner不支持android:drawSelectorOnTop此属性    -->    <Spinner        android:id="@+id/Spinner01"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:drawSelectorOnTop="true"             android:prompt="@string/planet_prompt" >    </Spinner><!--         Creates a TextView called SpinnerResult, below the spinner. -->    <TextView        android:id="@+id/SpinnerResult"        android:layout_width="fill_parent"        android:layout_height="fill_parent"        android:gravity="center"        android:text="Result"        android:textSize="10pt"        android:textStyle="bold" >    </TextView></LinearLayout>

strings.xml

<?xml version="1.0" encoding="utf-8"?><!--    The string named "app_name" defines the application's visible name.    The string array "Planets" defines an array of 9 strings. The application loads    this array into the spinner's array adapter.    The string "planet_prompt" defines the prompt for the result text box. --><resources>    <string name="app_name">Spinner</string>    <string-array name="Planets">        <item>Mercury</item>        <item>Venus</item>        <item>Earth</item>        <item>Mars</item>        <item>Jupiter</item>        <item>Saturn</item>        <item>Uranus</item>        <item>Neptune</item>        <item>Pluto</item>    </string-array>    <string name="planet_prompt">Select a planet</string></resources>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="cn.lyj.android"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk android:minSdkVersion="10" />    <application        android:icon="@drawable/ic_launcher"        android:label="@string/app_name" >        <activity            android:label="@string/app_name"            android:name=".AndroidUIActivity" >            <intent-filter >                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>    </application></manifest>

二. 运行结果

启动

点击菜单

选择Pluto

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