Java Program for Decimal to Binary Conversion
Last Updated :
10 Jul, 2024
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Given a decimal number as input, we need to write a program to convert the given decimal number into an equivalent binary number.
Examples:
Input : 7
Output : 111Input: 33
Output: 100001
Binary-to-decimal conversion is done to convert a number given in the binary system to its equivalent in the decimal number system. A number system is a format to represent numbers in a certain way.
Binary Number System - The binary number system is used in computers and electronic systems to represent data, and it consists of only two digits which are 0 and 1.
Decimal Number System - The decimal number system is the most commonly used number system worldwide, which is easily understandable to people. It consists of digits from 0 to 9.
Methods For Decimal to Binary Conversion
There are numerous approaches to converting the given decimal number into an equivalent binary number in Java. A few of them are listed below.
- Using Arrays
- Using Bitwise Operators
- Using Math.pow() Function (Without using arrays)
1. Using Arrays
Algorithm
- Store the remainder when the number is divided by 2 in an array.
- Divide the number by 2
- Repeat the above two steps until the number is greater than zero.
- Print the array in reverse order now.
The below diagram shows an example of converting the decimal number 17 to an equivalent binary number.
Java Program to Convert Decimal Number to Binary Using Arrays
// Java program to convert a decimal
// number to binary number
import java.io.*;
class GFG
{
// function to convert decimal to binary
static void decToBinary(int n)
{
// array to store binary number
int[] binaryNum = new int[1000];
// counter for binary array
int i = 0;
while (n > 0)
{
// storing remainder in binary array
binaryNum[i] = n % 2;
n = n / 2;
i++;
}
// printing binary array in reverse order
for (int j = i - 1; j >= 0; j--)
System.out.print(binaryNum[j]);
}
// driver program
public static void main (String[] args)
{
int n = 17;
System.out.println("Decimal - " + n);
System.out.print("Binary - ");
decToBinary(n);
}
}
// Java program to convert a decimal// number to binary numberimport java.io.*;class GFG { // function to convert decimal to binary static void decToBinary(int n) { // array to store binary number int[] binaryNum = new int[1000]; // counter for binary array int i = 0; while (n > 0) { // storing remainder in binary array binaryNum[i] = n % 2; n = n / 2; i++; } // printing binary array in reverse order for (int j = i - 1; j >= 0; j--) System.out.print(binaryNum[j]); } // driver program public static void main (String[] args) { int n = 17; System.out.println("Decimal - " + n); System.out.print("Binary - "); decToBinary(n); }}Output
Decimal - 17 Binary - 10001
The complexity of the above method:
Time Complexity: O(log2(n))
Auxiliary Space: O(1000)
2. Using Bitwise Operators
We can use bitwise operators to do the above job.
Note - Bitwise operators work faster than arithmetic operators used above.
Java Program to Convert Decimal Number to Binary Using Bitwise Operators
// Java program to Decimal to binary conversion
// using bitwise operator
// Size of an integer is assumed to be 32 bits
class gfg {
// Function that convert Decimal to binary
public void decToBinary(int n)
{
// Size of an integer is assumed to be 32 bits
for (int i = 31; i >= 0; i--) {
int k = n >> i;
if ((k & 1) > 0)
System.out.print("1");
else
System.out.print("0");
}
}
}
class geek {
// driver code
public static void main(String[] args)
{
gfg g = new gfg();
int n = 32;
System.out.println("Decimal - " + n);
System.out.print("Binary - ");
g.decToBinary(n);
}
}
// Java program to Decimal to binary conversion// using bitwise operator// Size of an integer is assumed to be 32 bitsclass gfg { // Function that convert Decimal to binary public void decToBinary(int n) { // Size of an integer is assumed to be 32 bits for (int i = 31; i >= 0; i--) { int k = n >> i; if ((k & 1) > 0) System.out.print("1"); else System.out.print("0"); } }}class geek { // driver code public static void main(String[] args) { gfg g = new gfg(); int n = 32; System.out.println("Decimal - " + n); System.out.print("Binary - "); g.decToBinary(n); }}Output
Decimal - 32 Binary - 00000000000000000000000000100000
The complexity of the above method:
Time Complexity: O(1)
Auxiliary Space: O(1)
3. Using Math.pow() method (Without using Arrays)
Decimal to binary conversion can also be done without using arrays.
Java Program to Convert Decimal Number to Binary Using Math.pow() Method
// Java implementation of the approach
import java.io.*;
class GFG {
// Function to return the binary
// equivalent of decimal value N
static int decimalToBinary(int N)
{
// To store the binary number
int B_Number = 0;
int cnt = 0;
while (N != 0) {
int rem = N % 2;
double c = Math.pow(10, cnt);
B_Number += rem * c;
N /= 2;
// Count used to store exponent value
cnt++;
}
return B_Number;
}
// Driver code
public static void main(String[] args)
{
int N = 17;
System.out.println("Decimal - " + N);
System.out.print("Binary - ");
System.out.println(decimalToBinary(N));
}
}
// This code is contributed by ajit.
// Java implementation of the approachimport java.io.*;class GFG { // Function to return the binary // equivalent of decimal value N static int decimalToBinary(int N) { // To store the binary number int B_Number = 0; int cnt = 0; while (N != 0) { int rem = N % 2; double c = Math.pow(10, cnt); B_Number += rem * c; N /= 2; // Count used to store exponent value cnt++; } return B_Number; } // Driver code public static void main(String[] args) { int N = 17; System.out.println("Decimal - " + N); System.out.print("Binary - "); System.out.println(decimalToBinary(N)); }}// This code is contributed by ajit.Output
Decimal - 17 Binary - 10001
The complexity of the above method
Time Complexity: O(log n)
Auxiliary Space: O(1)
Steps for Conversion
- Initialize a decimal number to 10.
- Call the decimalToBinary() method with the decimal number as the argument.
- Inside the decimalToBinary() method, initialize variables remainder, quotient, and binaryNum.
- While the quotient is greater than 0, do the following:
a. Compute the remainder by taking the modulus of the quotient with 2.
b. Append the remainder to the beginning of the binaryNum string.
c. Update the quotient by dividing it by 2. - Return the binaryNum string.
- Print the decimal number and the binary representation of the number.
public class GFG {
// Main driver method
public static void main(String[] args)
{
int decimal = 10;
String binary = decimalToBinary(decimal);
System.out.println("Decimal: " + decimal);
System.out.println("Binary: " + binary);
}
public static String decimalToBinary(int n)
{
int remainder, quotient = n;
String binaryNum = "";
while (quotient > 0) {
remainder = quotient % 2;
binaryNum
= Integer.toString(remainder) + binaryNum;
quotient = quotient / 2;
}
return binaryNum;
}
}
public class GFG { // Main driver method public static void main(String[] args) { int decimal = 10; String binary = decimalToBinary(decimal); System.out.println("Decimal: " + decimal); System.out.println("Binary: " + binary); } public static String decimalToBinary(int n) { int remainder, quotient = n; String binaryNum = ""; while (quotient > 0) { remainder = quotient % 2; binaryNum = Integer.toString(remainder) + binaryNum; quotient = quotient / 2; } return binaryNum; }}Try it on GfG Practice 
Output
Decimal: 10 Binary: 1010
The complexity of the above method
Time Complexity: O(log n)
Auxiliary Space: O(log n)
Please refer complete article on Program for Decimal to Binary Conversion for more details!
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String: Decimal To Binary
