What is difference between FillParent and wrap content in android?

This example demonstrates how do I show the difference between fillParent and wrap content in android.

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?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=".MainActivity">
   <TextView
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      android:text="A wiki is run using wiki software, otherwise known as a wiki engine. A wiki
      engine is a type of content management system, but it differs from most other such systems,
      including blog software, in that the content is created without any defined owner or leader,
       and wikis have little inherent structure, allowing structure to emerge according to the needs
       of the users."/>
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:text="This is a Wrap text"/>
</RelativeLayout>

Step 3 − Add the following code to src/MainActivity.java

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
   }
}

Step 4 − Add the following code to androidManifest.xml

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

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −

FillParent/Match parent: Fill parent is the older version, the updated one is the match parent which takes the entire screen.

Wrap Content: Wrap content takes the length of the text and wraps its content. Example: “This is a Wrap Text”. The wrap content starts wrapping from “This” and ends at “text”.