Android : Using Button & Click-Event with example

Introduction :

In this article we will learn, how to use Button and Listen for Click-Events. We shall take an example to understand all these . To make the example clear and easy to understand we shall use another control called EditText.

Implementation using Example :

Create a new android project with name ButtonTutorial.
[If you are a beginner and don’t know how to create a project then read it here Creating HelloWorld Application in Android]
Type you application name as My Button Tutorial.
Provide package name as com.suvendu.tutorials.button
Open main.xml and delete the single TextView already present in the page(may be with a text ‘Hello World, ButtonTutorialActivity!’.
Drag a EditText and a Button on to the layout.
Change the id of the EditText to ‘@+id/txtShowCurTime‘
Change the id of the Button to ‘@+id/btnGenCurTime‘
Add a new string to strings.xml with Name ‘button’ and Value ‘Generate Current Time‘

Change the text of the Button to ‘@string/button’
[Your layout is ready now and the main.xml should look like this]

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:orientation="vertical" >

<EditText
 android:id="@+id/txtShowCurTime"
 android:layout_width="match_parent"
 android:layout_height="wrap_content" >
 <requestFocus />
 </EditText>

 <Button
 android:id="@+id/btnGenCurTime"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:text="@string/button" />

</LinearLayout>

Open your default activity file (Ex: ButtonTutorialActivity.java)
Declare two global variables
```
Button btnCTime;
 EditText txtCTime;
```

import respective packages

import android.widget.Button;
import android.widget.EditText;

Link these variables to the layout in OnCreate() as follows

btnCTime=(Button)findViewById(R.id.btnGenCurTime);
 txtCTime=(EditText)findViewById(R.id.txtShowCurTime);

We don’t want the OnScreenKeyBoard to appear when the cursor is on EditText so, let disable this.

txtCTime.setInputType(InputType.TYPE_NULL);
</li>
	<li>Set the OnClickListener for the Button

btnCTime.setOnClickListener(new OnClickListener() {

 @Override
 public void onClick(View vw) {

 }
 });

import the package for OnClickListener

import android.view.View.OnClickListener;

Now do the logic inside onClick() to show the current time
```
txtCTime.setText(new Date().toString());
```
You need to import java package for using Date
```
import java.util.Date;
```

Finally, the default activity file should look like

package com.suvendu.tutorials.button;

import java.util.Date;

import android.app.Activity;
import android.os.Bundle;
import android.text.InputType;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class ButtonTutorialActivity extends Activity {
    Button btnCTime;
    EditText txtCTime;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btnCTime=(Button)findViewById(R.id.btnGenCurTime);
        txtCTime=(EditText)findViewById(R.id.txtShowCurTime);
        txtCTime.setInputType(InputType.TYPE_NULL);
        btnCTime.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View vw) {
                txtCTime.setText(new Date().toString());
            }
        });
    }
}