2020 ~ whereisstuff

Encapsulation in java

whereisstuffDecember 15, 2020 No comments

Encapsulation:

Data encapsulation is used to hide the implementation details from users.
If a data member is private it means it can only be accessed within the same class.
No outside class can access private data member (variable) of other class.

Syntax:

class class_name
{
private data_members;
public methods()
{
}

}

Example program:

class Account {
    private int account_number;
    private int account_balance;

    public void show_Data() {
        account_number=13456;
        account_balance=5000;
        System.out.println("Before deposit of "+"account XXXXX"+account_number+" number of balance :"+account_balance);
    }

    public void deposit(int a) {
        if (a < 0) {
            System.out.println("Given amount is wrong...");
        } else
            account_balance = account_balance + a;
        System.out.println("After deposit of current balance :"+account_balance);
    }
}

class Encapsulation{
    public static void main(String args[])
    {
        Account ac=new Account();
        ac.show_Data();
        ac.deposit(200);
    }

}

Output:

Exception handling in java

whereisstuffDecember 03, 2020 No comments

Exception handling:

Exception in java is an indication of some unusual event.
Usually it indicates the error.
Various keywords used in handling the exception are :
try-A block of source code that is to be monitored for the exception.
catch -The catch block handles the specific type of exception along with the try block.
finally - It specifies the code that must be executed even though exception may or may not occur.
throw - Used to throw specific exception from the program code.
throws - It specifies the exceptions that can be thrown by a particular method.

Syntax:

class class_name
{
try
{
//Exception occures here
}
catch(Exception_type exception_variable)
{
//Exception handling here
}

}

Types of exception:

1) Built-in exceptions:

Before using exception:

public class Divide_By_Zero {
    public static void main(String args[]) {
        int a = 0, b = 0, c = 0;
        a = 5;
        b = 0;
        c = a / b;
        System.out.println(a + " divide by zero of value is : " + c);
    }

}

Output:

Handling above error by using exception:

public class Divide_By_Zero {
    public static void main(String args[])
    {
        int a = 0,b=0,c=0;
        try
        {
            a=5;
            b=0;
            c=a/b;
        }
        catch(ArithmeticException e)
        {
            System.out.println(a+" divide by zero is infinity.");
        }

    }

Output:

Another Example program:

public class Divide_By_Zero {
    public static void main(String args[]) {
        int a[] = new int[3];
        try {
            for (int i = 1; i <= 3; i++) {
                a[i] = i * i;
                System.out.println("Arrsy index"+"\t"+"Added value");
                System.out.println(i+"\t\t"+a[i]);
            }
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Array index is out of bounds.");
        }
    }

}

Output:

2) User-defined exception:

If you need to create user-defined exception, must be constructor method.

Example program:

import java.lang.Exception;
public class user_defined_exception extends Exception {

    public user_defined_exception(String msg) {
        super(msg);
    }
}
class Objects {
    public static void main(String args[]) {
        int age=15;
        try {
            if (age < 21) {
                throw new user_defined_exception("Your age is very less than the condition.");
            }
        } catch (user_defined_exception e) {
            System.out.println("This is exception block.");
            System.out.println(e.getMessage());

        } finally {
            System.out.println("Finally exception block is end.");
        }
    }
}

Output:

String handling in java

whereisstuffDecember 01, 2020 No comments

String handling:

String is a collection of character. In java, String defines the objects. The string object is used in order to handle some text.

Most widely used functions are,

1. The length() function:

It is used to count and return the number of characters presents.

Example program length():

import java.util.Scanner;
public class String_length {
     public static void main(String args[]) {
    Scanner sc = new Scanner(System.in);
        System.out.print("Enter any string: ");
        String a = sc.next();
        System.out.print("Length of "+a+" is : "+a.length()+" Characters \n");
     }


}

Output:

2. String compare:

Method 1:

import java.util.Scanner;
public class String_equals {
     public static void main(String args[]) {
         int i;
    Scanner sc = new Scanner(System.in);
        System.out.print("Enter any string: ");
        String a = sc.next();
        String str="Whereisstuff";
        if (a.equals(str))
        {
            System.out.println("Entered string "+a+" is equal to stored string("+str+").");
        }
        else
        {
           System.out.println("Entered string "+a+" is not equal to stored string("+str+").");
        }

     }

}

Method 2:

import java.util.Scanner;
public class String_compare_method2 {
     public static void main(String args[]) {
         int i;
    Scanner sc = new Scanner(System.in);
        System.out.print("Enter any string: ");
        String a = sc.next();
        String str="Whereisstuff";
        if (a==str)
        {
            System.out.println("Enterd string "+a+" is equal to stored string("+str+").");
        }
        else
        {
           System.out.println("Enterd string "+a+" is not equal to stored string("+str+").");
        }

     }

}

Output:

If condition:

Else condition:

3. String compare with ignore case:

import java.util.Scanner;

public class String_EqualsIgnore {

     public static void main(String args[]) {

         int i;

    Scanner sc = new Scanner(System.in);

        System.out.print("Enter any string: ");

        String a = sc.next();

        String str="Whereisstuff";

        if (a.equalsIgnoreCase(str))

        {

            System.out.println("Enterd string "+a+" is equal to stored string("+str+").");

        }

        else

        {

           System.out.println("Enterd string "+a+" is not equal to stored string("+str+").");

        }



     }

}

Output:

If condition:

Else condition:

4. String to compare with array:

import java.util.Scanner;
public class String_Compare_in_Array {
    public static void main(String[] args) {
        int[] num = {1000, 2000, 3000, 4000};
        boolean found = false;
        Scanner input = new Scanner(System.in);
        System.out.println("Enter your PIN number : ");
        int pin = input.nextInt();
        for (int n : num) {
            if (n == pin) {
                found = true;
                break;
            }
        }
        if (found) {
            System.out.println("Entered PIN number is correct.");
        } else {
            System.out.println("Sorry try again!!!");
        }
    }

}

Output:

If condition:

Else part:

5. String upper and lower case:

import java.util.Scanner;
public class String_upper_lower {
    public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
        System.out.print("Enter any string in capital letters: ");
        String a = sc.next();
        System.out.print("Entered string is converted upper into lower : "+a.toLowerCase()+"\n");
        System.out.print("Enter any string in small letters: ");
        String b = sc.next();
        System.out.print("Entered string is converted lower into upper : "+b.toUpperCase()+"\n");
    }
}