Android入门之EditText（纯Java）

Android入门之EditText（纯Java）

1. import Android.app.Activity;  
2. import android.os.Bundle;  
3. import android.text.Editable;  
4. import android.text.TextWatcher;  
5. import android.widget.*;  
6.   
7. public class EditTextTest extends Activity {  
8.      
9.     private LinearLayout mainLayout=null;  
10.       
11.     private RelativeLayout layout=null;   
12.     private TextView tv1=null;      //标题           
13.     private TextView tv2=null;      //可输入剩余字符数   
14.     private EditText et=null;       //输入框          
15.       
16.     public void onCreate(Bundle savedInstanceState) {  
17.         super.onCreate(savedInstanceState);  
18.         mainLayout_init();  
19.         setContentView(mainLayout);  
20.     }  
21.     /*mainLayout初始化*/  
22.     void mainLayout_init(){  
23.         mainLayout=new LinearLayout(this);  
24.         LinearLayout.LayoutParams lp=new LinearLayout.LayoutParams(-1, -1);  
25.         mainLayout.setLayoutParams(lp);  
26.         mainLayout.setOrientation(LinearLayout.VERTICAL);  
27.         layout_init();  
28.         mainLayout.addView(layout);  
29.         et_init();  
30.         mainLayout.addView(et);  
31.     }  
32.     /*layout1初始化*/  
33.     void layout_init(){  
34.         layout=new RelativeLayout(this);  
35.         RelativeLayout.LayoutParams lp=new RelativeLayout.LayoutParams(-1, -2);  
36.         layout.setLayoutParams(lp);  
37.         tv1_init();  
38.         layout.addView(tv1);  
39.         tv2_init();  
40.         layout.addView(tv2);  
41.     }  
42.     /*tv11初始化*/  
43.     void tv1_init(){  
44.         tv1=new TextView(this);  
45.         RelativeLayout.LayoutParams lp=new RelativeLayout.LayoutParams(-2, -2);  
46.         lp.addRule(RelativeLayout.ALIGN_PARENT_LEFT);  
47.         tv1.setLayoutParams(lp);  
48.         tv1.setTextSize(30);  
49.         tv1.setText("请输入账号:");  
50.     }  
51.     /*tv12初始化*/  
52.     void tv2_init(){  
53.         tv2=new TextView(this);  
54.         RelativeLayout.LayoutParams lp=new RelativeLayout.LayoutParams(-2, -2);  
55.         lp.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);  
56.         tv2.setLayoutParams(lp);  
57.         tv2.setTextSize(30);  
58.         tv2.setText("12");  
59.     }  
60.     /*et1初始化*/  
61.     void et_init(){  
62.         et=new EditText(this);  
63.         LinearLayout.LayoutParams lp=new LinearLayout.LayoutParams(-1,-2);  
64.         et.setLayoutParams(lp);  
65.         et.setSingleLine(true);  
66.         //字符变化监听   
67.         TextWatcher tw=new TextWatcher(){  
68.             public void afterTextChanged(Editable s) {  
69.                 //限制输入，最多允许输入12个   
70.                 if(et.length()>12){  
71.                     //截取字符串，舍弃最后一个   
72.                     et.setText((et.getText()).subSequence(0, 12));  
73.                     //设置光标。由于用setText函数会导致光标复位，所以重新设置光标到末尾   
74.                     et.setSelection(12);  
75.                 }  
76.                 //显示剩余可输入字符数   
77.                 tv2.setText(String.valueOf(12-et.length()));  
78.             }  
79.             public void beforeTextChanged(CharSequence s, int start, int count,int after) {}  
80.             public void onTextChanged(CharSequence s, int start, int before,int count) {}  
81.         };  
82.         et.addTextChangedListener(tw);  
83.     }  
84. }