Core Java Programming

Creating Package in Java

The listing below shows a package named package1 containing a single class. Class Ademo.

Ademo.java
/* =========================================================== File Name : Ademo.java Package Name : package1 WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ package package1; public class Ademo { public void show() { System.out.println("Display the Class packclass1"); } }
This source file should be named as class Ademo.Java and stored in the subdirectory package1. After compiling this file, a class Ademo.class file will created should be stored in the same subdirectory.

How to compile or make the package use under commands:

after compiling java create a folder named package1 under bin dir....

Now consider the other program as follows:

Test1.java

/*
===========================================================
File Name : Test1.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/AdvanceJavaProgramming
Created By : Bintu Chaudhary
===========================================================
*/
import java.io.*;
import package1.Ademo;
class Test1
{
	public static void main(String args[])
	{
		package1.Ademo obj = new package1.Ademo();
		obj.show();
	}
}

Output

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Ademo	Test1
-	-
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Implementing Interface in Java

/*
===========================================================
File Name : ImplementingInterface.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/AdvanceJavaProgramming
Created By : Bintu Chaudhary
===========================================================
*/
import java.io.*;
interface inter //interface define
{
	void show();
}
class interclass implements inter // implement the interface
{
	public void show()
	{
                System.out.println("Hello Java - Interface");
	}
}
class ImplementingInterface
{
	public static void main(String args[])
	{
		interclass obj = new interclass();
		obj.show();
	}
}

Output of "ImplementingInterface.java"

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Extending Interface in Java

/*
===========================================================
File Name : ExtendingInterface.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/AdvanceJavaProgramming
Created By : Bintu Chaudhary
===========================================================
*/
import java.io.*;
interface inter1
{
	int a = 100;
	final static int b = 200;
}
interface inter2 extends inter1
{
	void show();
}
class interclass implements inter2
{
	public void show()
	{
		int c = a + b;
		System.out.println("Sum="+c);
	}
}
class ExtendingInterface
{
	public static void main(String args[])
	{
		interclass obj = new interclass();
		obj.show();
	}
}

Output of "ExtendingInterface.java"

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Wrapper Classes in Java

    
public class WrapperExample
{  
	public static void main(String args[])
	{  		
		int a=20;  
		Integer i=Integer.valueOf(a);//converting int into Integer explicitly  
		Integer j=a;//autoboxing, now compiler will write Integer.valueOf(a) internally  
  
		System.out.println(a+" "+i+" "+j);  
	}
}

Output

Java Vectors

/*
===========================================================
File Name : vectorclass.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/AdvanceJavaProgramming
Created By : Bintu Chaudhary
===========================================================
*/
import java.io.*;
import java.util.*;
class vectorclass
{
 public static void main(String args[])
 {
  Vector list = new Vector();
  int l = args.length;
  for (int i=0; i < l; i++)
  {
   list.addElement(args[i]);
  }
  list.insertElementAt("Bintu",2);
  int s = list.size();
  String larr[]=new String[s];
  list.copyInto(larr);
        
  System.out.println("List of Elements");
  for (int i=0; i < s; i++)
  {
   System.out.println(larr[i]);
  }
 }
}

Output of "VectorClass.java"

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StringBuffer Class in Java

/*
===========================================================
File Name : Str_Buffer.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/AdvanceJavaProgramming
Created By : Bintu Chaudhary
===========================================================
*/
import java.io.*;
class Str_Buffer
{
	public static void main(String args[]) throws Exception
	{
		String nm[]={"Bintu","Chaudhary"};

		System.out.println("First Name is :" +nm[0]);
		System.out.println("Last Name is :" +nm[0]);
		System.out.println("Uppercase :" +nm[0].toUpperCase());
		System.out.println("Full Name is :" +nm[0].concat(nm[0]));
		System.out.println("Extructed Strings is :" +nm[0].substring(2,5));     
	}
}

Output of "Str_Buffer.java"

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Java String and String Methods

/*
===========================================================
File Name : Str_StrMethod.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/AdvanceJavaProgramming
Created By : Bintu Chaudhary
===========================================================
*/
import java.io.*;
class Str_StrMethod
{
 static String n[] = {"Madras","Delhi","Ahmedabad","Bombay"};
 public static void main(String args[]) throws Exception
 {
  int s = n.length;
  String t =null;
        
  for(int i=0; i < s; i++)
  {
   for(int j=i+1; j < s; j++)
   {
    if(n[j].compareTo(n[i]) < 0) //compareTo String Method
    {
     t = n[i];
     n[i] = n[j];
     n[j] = t;                  
    }
   }
  }
  for(int i=0; i < s; i++)
  {
   System.out.println(n[i]);
  }
 }
}

Output of "Str_StrMethod.java"

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Two Dimensional Array in Java

/*
===========================================================
File Name : TwoDimensionalArray.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/AdvanceJavaProgramming
Twitter : https://twitter.com/AdvanceJava
Created By : Bintu Chaudhary
===========================================================
*/
import java.io.*;
class TwoDimensionalArray
{
 public static void main(String args[]) throws Exception
 {
  int a[][] = new int[2][3];
  int sum = 0;
  String n;
  int r,c;

  System.out.println("Enter the Elements");
  BufferedReader obj=new BufferedReader(new InputStreamReader(System.in));

  for(r=0;r< 2; r++)
  {
   for(c=0; c< 3; c++)
   {
    n = obj.readLine();
    a[r][c]=Integer.parseInt(n);
   }
  }
  System.out.println("After the Inputting");
  
  for(r=0; r< 2; r++)
  {
   for(c=0; c < 3; c++)
   {
    System.out.println("\t" +a[r][c]);
    sum = sum + a[r][c];
   }
   System.out.println("\n");
  }
  System.out.println("Sum="+sum);
 }
}

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One Dimensional Array in Java

/*
=======================================================
File Name : OneDimensionalArray.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/AdvanceJavaProgramming
Twitter : https://twitter.com/AdvanceJava
Created By : Bintu Chaudhary
=======================================================
*/
import java.io.*;
class OneDimensionalArray
{
	public static void main(String args[]) throws Exception
	{
		int i=0;
		int a[] = new int[10];
		String n;

		System.out.println("Enter the Elements");
		BufferedReader obj=new BufferedReader(new InputStreamReader(System.in));

		for(i=0;i< 5; i++)
		{
			n = obj.readLine();
			a[i]=Integer.parseInt(n);
		}
		System.out.println("After the Inputting");
		for(i=0; i< 5; i++)
		{
			System.out.println("a[ "+i+"]"+"="+a[i]);
		}
	}
}

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Method Overriding in Java

/*
=======================================================
File Name : MethodOverriding.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/AdvanceJavaProgramming
Twitter : https://twitter.com/bintuchaudhary
Created By : Bintu Chaudhary
=======================================================
*/
import java.io.*;
class over
{
	void show() 
	{
		System.out.println("\n\tJava Programming");
	}
}        
class riding extends over
{
	void show() 
	{
		System.out.println("\n\tAdvance Java Programming");
	}
}        
class MethodOverriding
{
	public static void main(String args[])
	{
		riding obj=new riding(); 
		obj.show();        
	}
}

Output of "MethodOverriding.java"

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MultiLevel Inheritance in Java

/* ======================================================= File Name : MultiLevelInheritance.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/bintu.chaudhary.mks Twitter : https://twitter.com/bintuchaudhary Created By : Bintu Chaudhary ======================================================= */ import java.io.*; class base1 { public void show1() { System.out.println("\n\tBase1 Class"); } } class base2 extends base1 { public void show2() { System.out.println("\n\tDerived Class from Base1 Class"); } } class base3 extends base2 { public void show3() { System.out.println("\n\tDerived Class from base2 Class"); } } class MultiLevelInheritance { public static void main(String args[]) { base3 obj=new base3(); obj.show1(); obj.show2(); obj.show3(); } }

Output of "MultiLevelInheritance.java"

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Hierarchical Inheritance in Java

    class A
{  
	void AClassFun()
	{
		System.out.println("A Class...");
	}  
}  
class B extends A
{  
	void AClassFun()
	{
		System.out.println("B Class extends A...");
	}  
}  
class C extends A
{  
	void CClassFun()
	{
		System.out.println("C Class extends A...");
	}  
}  
class HierarchicalInher
{  
	public static void main(String args[])
	{  
		C obj=new C();  
		obj.CClassFun();  
		obj.AClassFun();  	
	}
}

Output

Single Inheritance in Java

/*
=======================================================
File Name : SingleInheritance.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/bintu.chaudhary.mks
Twitter : https://twitter.com/bintuchaudhary
Created By : Bintu Chaudhary
=======================================================
*/
import java.io.*;
class A
{
	void show()
	{
		System.out.println("\n\tShow the Method of A Class");
	}
}
class B extends A
{
	void display()
	{
		System.out.println("\n\tDisplay the Method of B Class");
	}
}
class SingleInheritance
{
	public static void main(String args[])
	{
		B obj=new B(); 
		obj.show();        
		obj.display();
	}
}

Output of "SingleInheritance"

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Inheritance - Extending a Class

/*
=======================================================
File Name : ExtendClass.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/bintu.chaudhary.mks
Twitter : https://twitter.com/bintuchaudhary
Created By : Bintu Chaudhary
=======================================================
*/
import java.io.*;
class student
{
        int a,b;
 student(int x, int y) //Constructor
 {
                a = x;
            b = y;
 }
  void show()
 {
          int mul = a * b;
  System.out.println("\n\t=====================");
  System.out.println("\n\t FIRST CLASS\n");
  System.out.println("\t Multiplication="+mul);
 }
}
class student2 extends student
{
 int c,d;
  student2(int x,int y,int z,int r)
 {
   super(x,y);
   c = z;
   d = r; 
  }
  void display()
  {
  int sum = c + d;
  System.out.println("\n\n\t SECOND CLASS\n");
  System.out.println("\t Sum="+sum);
  System.out.println("\n\t=====================");
  }
}
class ExtendClass
{
 public static void main(String args[])
 {
   student2 obj=new student2(8,10,12,14); 
   obj.show();        
               obj.display();
  }
}

Output of "ExtendClass.java"

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Method Overloading in Java

/*
============================================
File Name : MethodOverloading.java
WebSite : http://javaproglang.blogspot.in/
Created By : Bintu Chaudhary
Email ID : bintu.chaudhary.mks@gmail.com
============================================
*/
import java.io.*;
class student
{
        int a,b,c;
        void Sum() 
 {
                a = 10;
                b = 20;

  c = a + b;

                System.out.println("\n\tSum of 1st Method="+c);
 }
        void Sum(int x)
 {
                a = b;
                c = x;

                System.out.println("\n\tSum of 2nd Method="+(a+c));
 }
        void Sum(int x,int y,int z)
 {
  a = x;
  b = y;
                c = z;

                System.out.println("\n\tSum of 3rd Method="+(a+b+c));
 }
}        
class MethodOverloading
{
 public static void main(String args[])
 {
                student obj=new student(); 
                obj.Sum();
                obj.Sum(20);
                obj.Sum(10,20,30);
 }
}

Output of "MethodOverloading.java"

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Finalize in Java

/*
============================================
File Name : FinalizeProgram.java
WebSite : http://javaproglang.blogspot.in/
Created By : Bintu Chaudhary
Email ID : bintu.chaudhary.mks@gmail.com
============================================
*/
import java.io.*;
class finl
{
 int a,b,c;
 finl() 
 {
  a = 100;
  b = 200;
 } 
 void get() 
 {
  System.out.println("Value of A and B");
 }
    void show()
    {
  c = a + b;
     System.out.println("Sum="+c);
    }
    protected void finalize()
    {
     System.out.println("Memory Released by Constructor");
    }
}        
class FinalizeProgram
{
 public static void main(String args[])
 {
  finl obj=new finl(); 
  obj.get();        
  obj.show();
  obj.finalize();
 }
}

Output of "FinalizeProgram.java"

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Copy Constructor, default Constructor, Parameterized Constructor

/*
============================================
File Name : CopyConstructor.java
WebSite : http://javaproglang.blogspot.in/
Facebook : https://www.facebook.com/bintu.chaudhary.mks
Twitter : https://twitter.com/bintuchaudhary
Created By : Bintu Chaudhary
============================================
*/
import java.io.*;
class box
{
 int h,w; //data members
 box() // default constructor
 {
  h=10;
  w=20;   
 }
 box(int x, int y)
 {
  h=x;
  w=y;
 }
 box(box obj) // Copy Constructor
 {
  h=obj.h;
  w=obj.w;
 }
 void show() // Member Function
 {
  System.out.println("\n\tHeight of Box is :\t"+h);
  System.out.println("\n\tWidth of Box is :\t"+w);  
 }
}        
class CopyConstructor
{
 public static void main(String args[])
 {
  box obj_box=new box();//instance of default constructor
  obj_box.show();
    
  box obj_box1=new box(120,30);//Instance of Parameterized Constructor
  obj_box1.show();
    
  box obj_box2=new box(obj_box1);//Instance of Copy Constructor
  obj_box2.show();
 }
}

Output of "CopyConstructor.java"

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Parameterized Constructor in Java

/*
============================================
File Name : ParamConstructor.java
WebSite : http://javaproglang.blogspot.in/
Created By : Bintu Chaudhary
Email ID : bintu.chaudhary.mks@gmail.com
============================================
*/
import java.io.*;
class student
{
 int a,b;
 student(int x, int y) //Parameterized Constructor
 {
  a = x;
  b = y;
 } 
 int sum() 
 {
  return(a+b);
 }
}        
class ParamConstructor 
{
 public static void main(String args[])
 {
  student obj=new student(40,80); 
  int sum= obj.sum();
  System.out.println("Sum="+sum);
 }
}

Out of "ParamConstructor.java"

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Constructor/Default Constructor/Empty Constructor in Java

/*
============================================
File Name : Constructor.java
WebSite : http://javaproglang.blogspot.in/
Created By : Bintu Chaudhary
Email ID : bintu.chaudhary.mks@gmail.com
============================================
*/
import java.io.*;
class student
{
 int a,b;
 student() //Constructor
 {
  a = 100;
  b = 200;
 } 
 void sum() 
 {
  int c = a + b;
  System.out.println("Sum = "+c);
 }
}        
class Constructor
{
 public static void main(String args[])
 {
  student obj=new student(); 
  obj.sum();
 }
}

Output of "Constructor.java"

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First Complete Class Program in Java

//============================================
/*
File Name : CompleteClassProgram.java
WebSite : http://javaproglang.blogspot.in/
Created By : Bintu Chaudhary
Email ID : bintu.chaudhary.mks@gmail.com
*/
//============================================
import java.io.*;
class base
{
 int a,b;
 void get() //Defination of Methods
 {
  a = 100;
  b = 200;
 } 
 void sum() //Defination of another method
 {
  int c = a + b;
  System.out.println("Sum = "+c);
 }
}        
class CompleteClassProgram //class with main method
{
 public static void main(String args[])
 {
  base obj=new base(); //creating object
  obj.get(); //Accessing Methods
  obj.sum();
 }
}

Output of "CompleteClassProgram.java"

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Java Tutorials

	Section 1
	Home
	Introduction To Java
	Java Evolution
	Overview of Java
	Constants, Variables & Data Types
	Java Operators
	Branching Statements
	Looping Statements
	Section 2
	Classes, Objects & Methods
	Inheritance
	Array, String & Vectors
	Java Interfaces
	Java Packages
	Java Applet Programming
	Java Graphics Programming
Advance Java Programming
	Section 1
	Java AWT
	Java Event Handling
	Java File Handling
	Java MultiThreading
	Java Swing-I
	Java Swing-II
	Java Exception Handling
	Section 2
	Java Socket Programming
	Java Database Connectivity
	Java RMI
	Java Servlets
	Java Beans

Creating Package in Java

Implementing Interface in Java

Extending Interface in Java

Wrapper Classes in Java

Java Vectors

StringBuffer Class in Java

Java String and String Methods

Two Dimensional Array in Java

One Dimensional Array in Java

Method Overriding in Java

MultiLevel Inheritance in Java

Hierarchical Inheritance in Java

Single Inheritance in Java

Inheritance - Extending a Class

Method Overloading in Java

Finalize in Java

Copy Constructor, default Constructor, Parameterized Constructor

Parameterized Constructor in Java

Constructor/Default Constructor/Empty Constructor in Java

First Complete Class Program in Java

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