Hello Readers! In this post, we are going to discuss about android radio button widget. We will also learn about different attributes of radio button that are used to customise this widget.

Output

Tutorialwing Android Radio Button Output

Getting Started

Android Radio Button can be defined as below –

An Android Radio Button is a two states button that can either be checked or unchecked. When the radio button is in unchecked state, it can be pressed or clicked to check it. Unlike Checkbox, it can not be unchecked (by clicking it) once it is checked.

We normally use Radio Buttons in Radio Group. When there are many radio buttons in Radio Group, Checking one radio button unchecks all other radio buttons.

Attributes of Android Radio Button Widget

Attributes of Radio Button are inherited from Compound Button, TextView and View. Some of the popular attributes of Radio Button inherited from TextView are –

Some of the popular attributes of Radio Button inherited from Compound Button are –

Some of the popular attributes of Radio Button inherited from View are –

Example of Android Radio Button Widget

At first, we will create android application. Then, we will use Radio Button in android application.

1. Creating New Project

Follow the steps below to create new project. Please ignore the steps if you have already created a new application.

Now, we will modify xml and java file to use radio button in the application.

2. Modify Values folder

Open res/values/strings.xml file. Then, add below code into it.

<resources>
	<string name="app_name">RadioButton</string>
</resources>

Other values folder have not been changed. So, we are not going to mention it here.

3. Use Radio Button Widget in xml file

Open res/layout/activity_main.xml file. Then, add below code into it.

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

	<RadioGroup
		android:id="@+id/radioGroup"
		android:layout_width="match_parent"
		android:layout_height="wrap_content"
		android:paddingLeft="20dp">

		<RadioButton
			android:id="@+id/radioMale"
			android:layout_width="wrap_content"
			android:layout_height="wrap_content"
			android:padding="10dp"
			android:text="Male"/>

		<RadioButton
			android:id="@+id/radioFemale"
			android:layout_width="wrap_content"
			android:layout_height="wrap_content"
			android:padding="10dp"
			android:text="Female"/>

	</RadioGroup>

</LinearLayout>

As mentioned earlier, Radio Button can not be unchecked, by clicking it, once it is checked. So, we use it with Radio Group and other radio buttons. When several radio buttons are used in a radio group, clicking on any radio button checks it and unchecks all other radio buttons. Thus, only one radio button can be selected at any time.

In activity_main.xml file, we have used two radio buttons inside a radio group. One radio button represents gender male, other represents female. So, If you want to select gender, you can either select male or female.

Radio button is used in similar situations like when you want to select only one option out of many options.

4. Access Radio Button Widget in java file

Open src/main/java/com.tutorialwing.radiobutton/MainActivity.java file. Then, add below code into it.

package com.tutorialwing.radiobutton;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.RadioGroup;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		final RadioGroup radioGroup = findViewById(R.id.radioGroup);
		if (radioGroup != null) {
			radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
				@Override
				public void onCheckedChanged(RadioGroup group, int checkedId) {
					String text = "You selected: ";
					text += (R.id.radioMale == checkedId) ? "male" : "female";
					Toast.makeText(getApplicationContext(), text, Toast.LENGTH_SHORT).show();
				}
			});
		}
	}
}

In MainActivity file, we are accessing radio buttons defined in xml file. Then we are showing a toast message when selection changes in radio group i.e. we are showing a toast message when any radio button is selected.

Since AndroidManifest.xml file is very important in any android application. We are also going to see the content of this file.

AndroidManifest.xml

Code inside src/main/AndroidManifest.xml file is as below –

<?xml version="1.0" encoding="utf-8"?>
<manifest package="com.tutorialwing.radiobutton"
		  xmlns:android="http://schemas.android.com/apk/res/android">

	<application
		android:allowBackup="true"
		android:icon="@mipmap/ic_launcher"
		android:label="@string/app_name"
		android:roundIcon="@mipmap/ic_launcher_round"
		android:supportsRtl="true"
		android:theme="@style/AppTheme">
		<activity android:name=".MainActivity">
			<intent-filter>
				<action android:name="android.intent.action.MAIN"/>

				<category android:name="android.intent.category.LAUNCHER"/>
			</intent-filter>
		</activity>
	</application>

</manifest>

When you run the application, you will get output as shown above.

That’s end of our tutorial on Android Radio Button.