What is fragment in android

Android fragment

Being a part of an activity, the Fragment in Android is also known as a sub-activity, i.e an activity can have more than one fragment. Multiple screens are represented by the fragments in an activity. Since the fragments are included in the activity, the Android fragment lifecycle gets affected by the activity lifecycle. Also since the fragments are embedded in an activity, a fragment has its own life cycle methods that are affected by the activity life cycle. To make the interaction between the fragment objects, the FragmentManager class is used.

Android Fragment Example:

In the below example, we are demonstrating the usage of the Android fragment.

File: activity _main.xml:

In the activity_main.xml file, we will add the TabLayout and ViewPager view components.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.radioapp.MainActivity">
    <android.support.design.widget.TabLayout
        android:id="@+id/tabLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#1db995">
    </android.support.design.widget.TabLayout>
    <android.support.v4.view.ViewPager
        android:id="@+id/viewPager"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/tabLayout"
        android:layout_centerInParent="true"
        android:layout_marginTop="100dp"
        tools:layout_editor_absoluteX="8dp" />
</RelativeLayout>

File: build.gradle:

In the build.gradle file, we will add the dependency library of the TabLayout.

apply plugin: 'com.android.application'
 
android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.radioapp"
        minSdkVersion 23
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}
 
dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:design:28.0.0'
    implementation 'com.android.support:support-v4:28.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

For all different tabs, we will create different fragment files.

File: Home.java:

package com.example.radioapp;
 
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
 
import app.com.sample.R;
 
public class Home extends Fragment {
    public Home() {
        // Required empty public constructor
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_home, container, false);
    }
}

File: About.java:

package com.example.radioapp;
 
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
 
import app.com.sample.R;
 
public class About extends Fragment {
    public About() {
        // Required empty public constructor
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_about, container, false);
    }
}

File: fragment_about.xml:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".About">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:textAlignment="center"
        android:text="About Fragment"
        android:textSize="16sp"
        android:textStyle="bold"/>
</FrameLayout>

File: Blog.java:

package com.example.radioapp;
 
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
 
import app.com.sample.R;
 
public class Blog extends Fragment {
    public Blog() {
        // Required empty public constructor
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_blog, container, false);
    }
}

File: fragment_blog.xml:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Blog">
    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:textAlignment="center"
        android:text="Blog Fragment"
        android:textSize="16sp"
        android:textStyle="bold"/>
</FrameLayout>