Java tutorial for beginners

Java program to generate random numbers

Objectives:

  • Write a Java program to to generate random numbers and print the same
  • Write a program to generate random numbers
  • Write a program to generate random numbers in Java

Java Program:

[sourcecode lang="java"]

import java.util.Scanner;
import java.util.Random;

class GenerateRandomNumber
{
public static void main(String[] args)
{
int maxRange;

//create objects
Scanner SC = new Scanner(System.in);
Random rand = new Random();

System.out.print("Please enter maximum range: ");
maxRange=SC.nextInt();

for(int i=1; i<=10; i++)
{
System.out.println(rand.nextInt(maxRange));
}
}
}

[/sourcecode]

Output:

Please enter maximum range: 500
467
61
100
449
68
316
445
224
54
498

August 31, 2021 by Java Source Code Java Tutorials 0

Find duplicate characters in string

Objectives:

  • Write a Java program to find duplicate characters in the string and print the duplicate characters
  • Write a program to find duplicate characters in String

Java Program:

[sourcecode lang="java"]
public class DuplicateCharacters {
    public static void main(String args[]) {

        String str = "NITIN";
        int count = 0;

        char input[] = str.toCharArray();
        System.out.println("Duplicate Characters are:");

        for (int i = 0; i &amp;lt; str.length(); i++) {
            for (int j = i + 1; j &amp;lt; str.length(); j++) {
                if (input[i] == input [j]) {
                    System.out.println(input[j]);
                    count++;
                    break;
                }
           }
        }
    }
}
[/sourcecode]

Output:

Duplicate Characters are: N I

August 30, 2021 by Java Source Code Java Tutorials 0

Using For Each in Java

Objective:

  • How to use For Each in Java?
  • How to use advance for in Java?
  • How to use advance for loop in Java Programming Language?
  • Types of For loop in Java

 

Source Code:

[sourcecode lang=”Java”]

class ForEachExample
{
public static void main(String args[])
{
//declaring an array
int a[]={1,2,3,4,5,6};

// Old way
System.out.println("Old way");
for(int i=0; i<a.length;i++)
{
System.out.println(a[i]);
}

//New way: for-each loop
System.out.println("For each");
for(int i:a)
{
System.out.println(i);
}
}
}

[/sourcecode]

April 2, 2020 by Java Source Code Java Tutorials 0

Pattern Programs in Java – Pattern 2

Pattern 2 :

1
2 2
3 3 3
4 4 4 4
5 5 5 5 5

Java Program for the above pattern:

[sourcecode language=”java”]

import java.util.Scanner;

public class MainClass

{

public static void main(String[] args)

{

Scanner sc = new Scanner(System.in);

//Taking rows value from the user
System.out.println("How many rows you want in this pattern?");

int rows = sc.nextInt();

System.out.println("Here is your pattern….!!!");

for (int i = 1; i <= rows; i++)

{

for (int j = 1; j <= i; j++)

{

System.out.print(i+" ");

}

System.out.println();

}

//Close the resources
sc.close();

}

}

[/sourcecode]

June 11, 2018 by How to's Java Source Code Java Tutorials 0

Pattern Programs In Java – Pattern 1

Q. Write a Java program to print given pattern.

Pattern 1 :

1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6
1 2 3 4 5 6 7

 

Java Program:

[sourcecode language=”java”]

import java.util.Scanner;

public class MainClass

{

public static void main(String[] args)

{

Scanner sc = new Scanner(System.in);

//Taking rows value from the user

System.out.println("How many rows you want in this pattern?");

int rows = sc.nextInt();

System.out.println("Here is your pattern….!!!");

for (int i = 1; i <= rows; i++)

{

for (int j = 1; j <= i; j++)

{

System.out.print(j+" ");

}

System.out.println();

}

//Close the resources

sc.close();

}

}

[/sourcecode]

May 21, 2018 by Java Source Code Java Tutorials 0

Java Program to convert Decimal values to Hexadecimal values

Objectives :

  • How to convert Decimal to Hexadecimal in Java?

 

Java Program to convert Decimal values to Hexadecimal values : 

[sourcecode lang=”java”]

import java.util.Scanner;

public class DecimalToHexadecimal {

public static void main(String[] args) {

Scanner input = new Scanner(System.in);

System.out.print("Enter decimal number you like: ");
int deci = input.nextInt();

System.out.println("The hexadecimal number for decimal "
+ deci + " is " + convert(deci));
}

public static String convert(int decimal) {
String hex = "";

while (decimal != 0) {
int hexValue = decimal % 16;
hex = toHexadecimal(hexValue) + hex;
decimal = decimal / 16;
}

return hex;
}

public static char toHexadecimal(int hexValue) {
if (hexValue <= 9 && hexValue >= 0) {
return (char) (hexValue + ‘0’);
} else {
return (char) (hexValue – 10 + ‘A’);
}
}
}

[/sourcecode]

Output :
Enter decimal number you like: 1234
The hexadecimal number for decimal 1234 is 4D2

April 20, 2016 by Java Source Code Java Tutorials NetBeans IDE Source Code 0

Java Program to Convert Decimal Number to Roman Number

Objectives :

  • Convert Decimal number to Roman number
  • Convert Decimal numeral to Roman numeral
  • How to convert a decimal number to roman number
  • Write a program that converts a decimal number to Roman number.
  • Write a program that converts a decimal number to Roman number. Decimal Number is accepted using Scanner class at the time of execution.
  • Write a program that converts a decimal number to Roman number. Decimal Number is accepted as command line input at the time of execution.

 

Program : 

Java program that converts a decimal number to Roman number. Decimal Number is accepted using Scanner class at the time of execution.

[sourcecode lang=”java”]

&nbsp;

import java.util.Scanner;

public class DecimalToRoman {

private static String toRoman(int num) {
String[] romanCharacters = { "M", "CM", "D", "C", "XC", "L", "X", "IX", "V", "I" };
int[] romanValues = { 1000, 900, 500, 100, 90, 50, 10, 9, 5, 1 };
String result = "";

for (int i = 0; i < romanValues.length; i++) {
int numberInPlace = num / romanValues[i];
if (numberInPlace == 0) continue;
result += numberInPlace == 4 && i > 0? romanCharacters[i] + romanCharacters[i – 1]:
new String(new char[numberInPlace]).replace("\0",romanCharacters[i]);
num = num % romanValues[i];
}
return result;
}

public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number : ");
int decimal = scanner.nextInt();
System.out.println(toRoman(decimal));
}

}

[/sourcecode]

Output :

Enter a number : 1234

MCCXXXIV

Java program that converts a decimal number to Roman number. Decimal Number is accepted as command line input at the time of execution.

[sourcecode lang=”java”]

public class DecimalToRoman {

private static String toRoman(int num) {
String[] romanCharacters = { "M", "CM", "D", "C", "XC", "L", "X", "IX", "V", "I" };
int[] romanValues = { 1000, 900, 500, 100, 90, 50, 10, 9, 5, 1 };
String result = "";

for (int i = 0; i < romanValues.length; i++) {
int numberInPlace = num / romanValues[i];
if (numberInPlace == 0) continue;
result += numberInPlace == 4 && i > 0? romanCharacters[i] + romanCharacters[i – 1]:
new String(new char[numberInPlace]).replace("\0",romanCharacters[i]);
num = num % romanValues[i];
}
return result;
}

public static void main(String[] args) {
if(args.length<1 || args.length>1){
System.out.println("Wrong input");
}else{
String number = args[0];
int decimal = Integer.parseInt(number);
System.out.println(toRoman(decimal));
}
}

}

[/sourcecode]

March 28, 2016 by Java Source Code Java Tutorials NetBeans IDE Source Code 1

Java Program to convert Decimal to Binary

Objectives :

  • Decimal to Binary Conversion
  • Converting Decimal to Binary
  • Converting Decimal Number to Binary format
  • Write a program to convert decimal to binary
  • Write a program to convert decimal number to binary format
  • Write a program to convert positive decimal number to binary format
  • Write a program to convert decimal to binary using Scanner class
  • Write a program to convert decimal to binary, take input using Scanner class

 

Java Program to convert Decimal to Binary : 

[sourcecode lang=”java”]
public class DecimalToBinary {

public void toBinary(int number){
int binary[] = new int[25];
int n = 0;
// Convert Decimal to Binary
while(number > 0){
binary[n++] = number%2;
number = number/2;
}
// Print Binary number
for(int i = n-1;i >= 0;i–){
System.out.print(binary[i]);
}
}

public static void main(String[] args){
DecimalToBinary obj = new DecimalToBinary();
obj.toBinary(14);
}
}
[/sourcecode]

Output :

1110

 

Java Program to convert Decimal to Binary using Scanner class :

[sourcecode lang=”java”]

import java.util.Scanner;

public class DecimalToBinary {

public void toBinary(int number){
int binary[] = new int[14];
int n = 0;

// Convert Decimal to Binary
while(number > 0){
binary[n++] = number%2;
number = number/2;
}

// Print Binary Number
for(int i = n-1;i >= 0;i–){
System.out.print(binary[i]);
}
}

public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int num= scanner.nextInt();
DecimalToBinary obj = new DecimalToBinary();
obj.toBinary(num);

}
}

[/sourcecode]

Output :

Enter a number: 14

1110

March 15, 2016 by Java Tutorials 1

Java Program to find prime number upto N number

Objectives :

  • Write a Java program to find prime number upto N number
  • Write a Java program to print prime number upto N number
  • Write a Java program to find prime number upto N number using Command Line Arguments
  • Write a Java Program to find prime number upto N number via Command Line Arguments
  • Write a Java program to find prime number upto N number using Scanner class

 

Java Program / Code :

Method 1 : Java Program to find Prime Number upto N number using Scanner class

[sourcecode lang=”Java”]

import java.util.Scanner;
class PrimeNumber
{
public static void main(String[] args)
{
int n,p;
Scanner s=new Scanner(System.in);
System.out.println(“Enter number : ”);
n=s.nextInt();
for(int i=2;i<n;i++)
{
p=0;
for(int j=2;j<i;j++)
{
if(i%j==0)
p=1;
}
if(p==0){
System.out.println(i);
}
}
}
}
[/sourcecode]

Method 2 : Java Program to find Prime Number upto N number using Scanner class and writing function to find prime number

Method isPrime() for checking if a number is prime or not

[sourcecode lang=”java”]
public class PrimeNumber{
public boolean isPrime(int num) {
if ( num < 2 ){
return false;
}
for (int i = 2; i <= Math.sqrt(num); i++) {
if ( num % i == 0 ) {
return false;
}
}
return true;
}
}

// Mock Test Class to test above code
import java.util.Scanner;

public class Demo
{
public static void main(String[] args)
{
Scanner scanner = new Scanner(System.in);

System.out.println("Please enter a number: ");
int num = scanner.nextInt();

if ( num < 2 ) {
System.out.println("\n There are no Prime Numbers available");
System.exit(0);
}
System.out.println("\n Prime Numbers from 1 to "+ num);
PrimeNumber primeNum = new PrimeNumber();

for (int i = 3; i <= num; i++) {
if ( primeNum.isPrime(i) ) {
System.out.print(", " + i);
}
}
}
}
[/sourcecode]

Method 3 : Java Program to find Prime Number upto N number using Command line input

[sourcecode lang=”Java”]

class PrimeNumber
{
public static void main(String[] args)
{
int n,p;
n=Integer.parseint(args[0]);
for(int i=2;i&lt;n;i++)
{
p=0;
for(int j=2;j&lt;i;j++)
{
if(i%j==0)
p=1;
}
if(p==0){
System.out.println(i);
}
}
}
}
[/sourcecode]

Steps to run above program via command line :

  1. Compilation : C:\JavaPrograms>javac PrimeNumber.java
  2. Interpretation : C:\JavaPrograms>java PrimeNumber 20

Output :

2

3

5

7

11

13

17

19

March 13, 2016 by Java Tutorials 1

Simple Interest Example in Java

Starting a series of some Java programs as many students were asking to share the programs. Here is the first program of the series.

Objectives:

  • Write a Program that calculates and prints the simple interest using the formula : Simple Interest = PTR/100
  • How to calculate Simple Interest in Java?
  • Write a program to calculate Simple Interest in Java.
  • Write a Java program that calculates and prints the simple interest using the formula : “SimpleInterest = PTR/100” and input values P, T, R should be accepted as command line.
  • How to use Command Line Arguments in Java?
  • How to pass values from command line in Java?
  • How to take input in Java from console?

 

This particular program can be written in various ways, we will try to write the solution program in different ways here and one can try to understand the difference between them.

Method 1 :

[sourcecode lang=”java”]
import java.util.Scanner;

public class SimpleInterestExample {

public static void main(String[] args) {

int p,t,r, result;

Scanner sc = new Scanner(System.in);

System.out.println(&quot;Enter the Value of P : &quot;);
p = sc.nextInt();

System.out.println(&quot;Enter the Value of T : &quot;);
t = sc.nextInt();

System.out.println(&quot;Enter the Value of R : &quot;);
r = sc.nextInt();

result = (p*t*r)/100;
System.out.println(&quot;Interest is : &quot; + result);
}
}
[/sourcecode]

This one is the simplest way to write the program to find simple interest in Java. Here we have simply created the object of Scanner class for taking input. Scanner class was introduced in Java 6. To use Scanner class we will have to import the class from java.util package.

Method 2:

Now we will write a Java program that calculates and prints the simple interest using the Scanner class again but with object oriented programming approach.

[sourcecode lang=”java”]
import java.util.Scanner;

public class SimpleInterestExample
{
double principalAmount = 0;
double interestRate = 0;
double term = 0;
double simpleInterest = 0;

public void calculateSimpleInterest()
{
Scanner input = new Scanner(System.in);

System.out.print(&quot;Enter the Principal amount : &quot;);
principalAmount = input.nextDouble();

System.out.print(&quot;Enter the Rate As a decimal : &quot;);
interestRate = input.nextDouble();

System.out.print(&quot;Enter the amount of time in years : &quot;);
term = input.nextDouble();

simpleInterest = (principalAmount * interestRate * term) / 100;
}

public void displaySimpleInterest()
{
System.out.println(&quot;The Simple Interest is : &quot; + simpleInterest);
}
}
[/sourcecode]

Mock Test Program for above code so that we can test the code. keep both the classes in same package and run the Mock Test Program or MockTestProgram.java

[sourcecode lang=”java”]
public class MockTestProgram{

public static void main(String[]args);
{
SimpleInterestExample simpleInt = new SimpleInterestExample();
simpleInt.calculateSimpleInterest();
simpleInt.displaySimpleInterest();
}
}
[/sourcecode]

Method 3:

Now we will write a Java program that calculates and prints the simple interest using the formula : “SimpleInterest = PTR/100” and input values P, T, R should be accepted as command line.

[sourcecode lang=”java”]
import java.util.Scanner;

public class SimpleInterestExample {

public static void main(String[] args) {
double p,t,r, result;

p = Double.parseDouble(args[0]);
t = Double.parseDouble(args[1]);
r = Double.parseDouble(args[2]);

Scanner sc = new Scanner(System.in);

System.out.println(&quot;Enter the Value of P : &quot;);
p = sc.nextDouble();

System.out.println(&quot;Enter the Value of T : &quot;);
t = sc.nextDouble();

System.out.println(&quot;Enter the Value of R : &quot;);
r = sc.nextDouble();

result = (p*t*r)/100;
System.out.println(&quot;Interest is : &quot; + result);
}
}
[/sourcecode]

 

I will be sharing more programs soon as many students were asking for programs which were carried out during Java training and were asked in assignments after Java training. By the time enjoy coding in Java and use NetBeans, it will ease your life.

July 20, 2015 by Java Source Code Java Tutorials 0