android练习demo1

Textview1

类似验证码的效果 点击之后生成一个随机的4位数，更换颜色。
代码如下

public class MainActivity extends Activity {private TextView text1;private Button btn1;private int color[] = { Color.BLUE, Color.BLACK, Color.GREEN, Color.RED };private Handler handler = new Handler() {public void handleMessage(Message msg) {if(msg.what==1){//核心代码如下Math.random();和Random().nextInt();text1.setText((int)(Math.random()*9000+1000)+"");text1.setTextColor(color[new Random().nextInt(4)]);}};};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);text1 = (TextView) findViewById(R.id.text1);btn1 = (Button) findViewById(R.id.btn1);btn1.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubnew Thread() {public void run() {init();};}.start();}});}private void init() {// TODO Auto-generated method stubMessage msg = new Message();msg.what = 1;handler.sendMessage(msg);}}

android 练习demo2

spinner

下拉列表框中的列表项主要有以下两种配置方式。

方式一、通过资源文件配置，例如定义一个values\city_data.xml的文件，在定义数据内容时需要使用元素指定，定义内容如下：

<?xml version="1.0" encoding="utf-8"?>
<resources><string-array name="city_items"><item >1</item><item >2</item><item >3</item><item >4</item><item >5</item></string-array>
</resources>

方式二、通过android.widget.ArrayAdapter类读取资源文件或者指定具体的数据。

定义布局xml文件

<LinearLayout 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:orientation="vertical"tools:context="com.example.demotest.MainActivity" ><TextView
        android:id="@+id/text1"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="选择你喜欢的数字" /><Spinner
        android:id="@+id/sp1"android:layout_width="match_parent"android:layout_height="wrap_content"android:entries="@array/city_items"/> <!-- 加载数据到spinner中 --></LinearLayout>

public class SpinnerText3 extends Activity {private Spinner spintener;private Spinner spintener2;private TextView textView;private List<String> data = null;private ArrayAdapter<String> adapter;public void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState); // 生命周期方法super.setContentView(R.layout.spinner2); // 设置要使用的布局管理器textView = (TextView) findViewById(R.id.text2);spintener = (Spinner) findViewById(R.id.sp1);spintener2 = (Spinner) findViewById(R.id.sp2);spintener2.setPrompt("选择国籍");data = new ArrayList<String>();data.add("中国");data.add("美国");data.add("日本");data.add("韩国");adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, data);spintener2.setAdapter(adapter);// 加载数据spintener.setOnItemSelectedListener(new OnItemSelectedListener() {@Overridepublic void onItemSelected(AdapterView<?> parent, View view, int position, long id) {// 拿到数组String[] cities = getResources().getStringArray(R.array.city_items);// 根据位置显示数据textView.setText("您选择的数字是" + cities[position]);}@Overridepublic void onNothingSelected(AdapterView<?> parent) {}});spintener2.setOnItemSelectedListener(new OnItemSelectedListener() {@Overridepublic void onItemSelected(AdapterView<?> parent, View view, int position, long id) {// TODO Auto-generated method stubString[] str = data.toArray(new String[data.size()]);Toast.makeText(SpinnerText3.this, "帅哥" + str[position], Toast.LENGTH_SHORT).show();;}@Overridepublic void onNothingSelected(AdapterView<?> parent) {// TODO Auto-generated method stub}});}