Java Program to show the use of some String Library classes

import java.io.*;
import java.util.*;
public class StringLibrary{
    Scanner scan=new Scanner(System.in);
    String first, last, replace, replaceWith, compare, compareWith, indexOf, number;
    int index;
    char character;
    public void input(){
        try{
            System.out.println("Enter your First Name: ");
            first=scan.nextLine();
            System.out.println("Enter your Last Name: ");
            last=scan.nextLine();
        }
        catch(Exception e){
            System.out.println("Error Code: "+e);
            System.exit(0);
        }
    }

    public void compute(){
        number=first.concat(" "+last);
        lengthString();
        characterIndex();
        replacing();
        compare();
        indexOf();
        caseConversion();
    }

    public void lengthString(){
        int length=first.length()+last.length();
        System.out.println("Length of String including blank spaces: "+length);
    }

    public void characterIndex(){
        try{
            System.out.println("Enter index number: ");
            index=scan.nextInt();
        }
        catch(Exception e){
            System.out.println("Error Code: "+e);
            System.exit(0);
        }
        System.out.println("Character at Index \""+index+"\" is: "+(number.charAt(index)));
    }

    public void replacing(){
        try{
            System.out.println("Enter any String you want to replace: ");
            replace=scan.next();
            System.out.println("Enter the String you want to replace with: ");
            replaceWith=scan.next();
        }
        catch(Exception e){
            System.out.println("Error Code: "+e);
            System.exit(0);
        }
        System.out.println("After replacing: "+(number.replace(replace, replaceWith)));
    }

    public void compare(){
        try{
            System.out.println("Enter the String you would like to compare: ");
            compare=scan.next();
            System.out.println("Enter the String you want to compare it with: ");
            compareWith=scan.next();
        }
        catch(Exception e){
            System.out.println("Error Code: "+e);
            System.exit(0);
        }
        System.out.println("Result in True/False:- \nString comparison: "+(compare.equals(compareWith)));
        if(compare.compareTo(compareWith)==0)
            System.out.println("Case Sensitive comparison: String Matches!");
        else
            System.out.println("Case Sensitive comparison: String Doesn't Matches!");
        if(compare.equalsIgnoreCase(compareWith))
            System.out.println("Non-Case Sensitive comparison: String Matches!");
        else
            System.out.println("Non-Case Sensitive comparison: String Mathces!");
    }

    public void indexOf(){
        try{
            System.out.println("Enter any character to view its first and last index: ");
            indexOf=scan.next();
            character=indexOf.charAt(0);
        }
        catch(Exception e){
            System.out.println("Error Code: "+e);
            System.exit(0);
        }
        System.out.println("First Index of \""+character+"\" is: "+(number.indexOf(character))+"\nLast Index: "+(number.lastIndexOf(character)));
    }

    public void caseConversion(){
        System.out.println("Your Name in Upper Case: "+(number.toUpperCase()));
        System.out.println("Your Name in Lower Case: "+(number.toLowerCase()));
    }

    public static void main(String[] args){
        StringLibrary obj=new StringLibrary();
        obj.input();
        obj.compute();
    }
}