android入门系列- TextView EditText Button ImageView 的简单应用

 1 public class MainActivity extends Activity {
 2 
 3     private TextView tv;
 4     private EditText et;
 5     private Button btn;
 6     private ImageView iv;
 7 
 8     @Override
 9     protected void onCreate(Bundle savedInstanceState) {
10         super.onCreate(savedInstanceState);
11         // 加载布局文件
12         setContentView(R.layout.activity_main);
13         // 初始化控件
14         init();
15         // 设置Button的OnClickListener监听器
16         btn.setOnClickListener(new OnClickListener() {
17             @Override
18             public void onClick(View v) {
19                 // 将et中输入的内容通过Toast显示出来
20                 Toast.makeText(MainActivity.this,
21                         "et的输入为：" + et.getText().toString(), Toast.LENGTH_SHORT)
22                         .show();
23             }
24         });
25         // 设置ImageView的OnClickListener监听器
26         iv.setOnClickListener(new OnClickListener() {
27             @Override
28             public void onClick(View v) {
29                 // 当点击btn的时候就让iv的图片变成另一张图片
30                 iv.setBackgroundResource(R.drawable.animal);
31             }
32         });
33     }
34 
35     private void init() {
36         tv = (TextView) this.findViewById(R.id.acMain_tv_username);
37         et = (EditText) this.findViewById(R.id.acMain_et_password);
38         btn = (Button) this.findViewById(R.id.acMain_btn_login);
39         iv = (ImageView) this.findViewById(R.id.acMain_iv_show);
40         tv.setText("Hello , this is gh");
41     }

 1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:paddingBottom="@dimen/activity_vertical_margin"
 6     android:paddingLeft="@dimen/activity_horizontal_margin"
 7     android:paddingRight="@dimen/activity_horizontal_margin"
 8     android:paddingTop="@dimen/activity_vertical_margin"
 9     tools:context="com.example.cnblogs001.MainActivity" >
10 
11     <TextView
12         android:id="@+id/acMain_tv_username"
13         android:layout_width="match_parent"
14         android:layout_height="wrap_content"
15         android:gravity="center_horizontal"
16         android:padding="10dp"
17         android:text="@string/hello_world"
18         android:textColor="@android:color/holo_blue_dark"
19         android:textSize="20sp" />
20 
21     <EditText
22         android:id="@+id/acMain_et_password"
23         android:layout_width="match_parent"
24         android:layout_height="wrap_content"
25         android:layout_below="@id/acMain_tv_username"
26         android:layout_marginTop="10dp"
27         android:ellipsize="end"
28         android:gravity="center_horizontal"
29         android:hint="@string/hint_et_password"
30         android:inputType="textPassword"
31         android:maxLines="1" />
32 
33     <Button
34         android:id="@+id/acMain_btn_login"
35         android:layout_width="match_parent"
36         android:layout_height="wrap_content"
37         android:layout_below="@id/acMain_et_password"
38         android:layout_marginTop="10dp"
39         android:alpha="0.5"
40         android:background="@android:color/holo_blue_dark"
41         android:gravity="center"
42         android:text="@string/text_btn_login"
43         android:textColor="#000000"
44         android:textSize="20sp" />
45 
46     <ImageView
47         android:id="@+id/acMain_iv_show"
48         android:layout_width="150dp"
49         android:layout_height="150dp"
50         android:layout_below="@id/acMain_btn_login"
51         android:layout_centerHorizontal="true"
52         android:layout_marginTop="10dp"
53         android:background="@drawable/logo"
54         android:scaleType="fitCenter" />
55 
56 </RelativeLayout>