Android Application Development BASICS (1) -- button

I. Overview

A button, as its name implies, is a button. Its main function is to respond to the actions when a user presses a button.

II. Application

Create a new project named mybutton and add the following content to the/RES/layout/Main. xml file:

1 <Button
2 android:id="@+id/button"
3         android:layout_width="fill_parent"
4         android:layout_height="wrap_content"
5         android:text="Click"
6 />

The content of the added main. xml file is:

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     android:layout_width="fill_parent"
 4     android:layout_height="fill_parent"
 5     android:orientation="vertical" >
 6 
 7     <TextView
 8 android:layout_width="fill_parent"
 9         android:layout_height="wrap_content"
10         android:text="@string/hello" />
11 
12     <Button
13 android:id="@+id/button"
14         android:layout_width="fill_parent"
15         android:layout_height="wrap_content"
16         android:text="Click"
17 />
18 
19 </LinearLayout>

Modify the mybuttonactivity. Java file and declare a button object mbutton in the mybuttonactivity class.

 

private Button mButton = null;

Use the findviewbyid () function in the oncreate () function to instantiate mbutton.

 

mButton = (Button)findViewById(R.id.button);

Then write the mbutton listening function.

 

mButton.setOnClickListener(new View.OnClickListener()
        {

            @Override
public void onClick(View v)
            {
// TODO Auto-generated method stub
                PlayToast("You Clicked Button");
            }
        });

The playtoast () function uses the toast class to display the string "you clicked button", which is relatively simple, as shown below:

private void PlayToast(String s)
    {
        Toast toast = Toast.makeText(this, s , Toast.LENGTH_LONG);
        toast.show();
    }

Okay. The following is the complete content of the mybuttonactivity. Java file:

 1 package com.nan.button;
 2 
 3 import android.app.Activity;
 4 import android.os.Bundle;
 5 import android.view.View;
 6 import android.widget.Button;
 7 import android.widget.Toast;
 8 
 9 
10 
11 public class MyButtonActivity extends Activity
12 {
13     private Button mButton = null;
14 
15 
16     /** Called when the activity is first created. */
17     @Override
18     public void onCreate(Bundle savedInstanceState)
19     {
20         super.onCreate(savedInstanceState);
21         setContentView(R.layout.main);
22 
23         mButton = (Button)findViewById(R.id.button);
24         mButton.setOnClickListener(new View.OnClickListener()
25         {
26 
27             @Override
28             public void onClick(View v)
29             {
30                 // TODO Auto-generated method stub
31                 PlayToast("You Clicked Button");
32             }
33         });
34 
35     }
36 
37 
38     private void PlayToast(String s)
39     {
40         Toast toast = Toast.makeText(this, s , Toast.LENGTH_LONG);
41         toast.show();
42     }
43 
44 }

Run the program and click the button. The effect is as follows: