Develop an application that uses GUI components, Font and Colours

 Simple application to change font size and color of textview

1)Open eclipse or android studio and select new android project

2)Give project name and select next
3) Choose the android version.Choose the lowest android version(Android 2.2) and select next
4) Enter the package name.package name must be two word seprated by comma and click finish
5)Go to package explorer in the left hand side.select our project.
6)Go to res folder and select layout.Double click the main.xml file
7)Now you can see the Graphics layout window.

8)Click the main.xml file and type the code below

<?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" >
    <TextView
        android:id="@+id/textView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="20sp"
        android:gravity="center"
        android:text="HELLO WORLD"
        android:textSize="20sp"
        android:textStyle="bold" />
    <Button
        android:id="@+id/button1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="Change font size"
        android:textSize="20sp" />
    <Button
        android:id="@+id/button2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="Change color"
        android:textSize="20sp" />
     <Button
        android:id="@+id/button3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="Change font"
        android:textSize="20sp" />
</LinearLayout>

9)Again click the graphics layout tab and screen layout is look like below

 10)Go to project explorer and select src folder.Now select mainactivity.java file and type the following code

//import android.R;
import android.app.Activity;
import android.graphics.Color;
import android.graphics.Typeface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class AndroidActivity extends Activity {
     float font =24;
     int i=1;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        final TextView t1=(TextView) findViewById(R.id.textView1);
      Button  b1 = (Button) findViewById(R.id.button1);

        b1.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {
                t1.setTextSize(font);
                font=font+4;
                if(font==40)
                    font=20;
            }
        });
        Button  b2 = (Button) findViewById(R.id.button2);
        b2.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {
                switch(i)
                {
                case 1:
                    t1.setTextColor(Color.parseColor("#0000FF"));
                    break;
                case 2:
                    t1.setTextColor(Color.parseColor("#00FF00"));
                    break;
                case 3:
                    t1.setTextColor(Color.parseColor("#FF0000"));
                    break;
                case 4:
                    t1.setTextColor(Color.parseColor("#800000"));
                    break;
                }
                i++;
                if(i==5)
                    i=1;
                 
            }
              
        });
   
}
}

11)Now go to main.xml and right click .select run as option and select run configuration

12) Android output is present in the android emulator as shown in below.