Java Program to Convert Integer Values into Binary - GeeksforGeeks

09 Feb, 2022
Given an integer in Java, your task is to write a Java program to convert this given integer into a binary number.
Example: 
Input:  = 45
Output: = 101101

Input:  = 32
Output: = 100000
Integers: Integers are numbers whose base value is 10. The Integer or int data type is a 32-bit signed two’s complement integer. Its value-range lies between – 2,147,483,648 (-2^31) to 2,147,483,647 (2^31 -1) (inclusive). Its minimum value is – 2,147,483,648 and maximum value is 2,147,483,647. Its default value is 0. The int data type is generally used as a default data type for integral values unless there is no problem with memory.
Binary Numbers: A binary number is a number expressed in the base-2 numeral. Binary consists of only 2 digits 0 and 1. Two operators are used in the conversion of integers to binary modulo and division to convert the given input into binary numbers.
There are many approaches to convert an integer into binary numbers some of them are discussed here. We will be discussing two of them:
Using Implementation of Stack
Using Inbuilt Method- toBinaryString() of the Integer class of Java
Actually, the binary number consists of only 0 and 1. To convert an integer to binary divide the number by 2 until it becomes 0. In each step take the modulo by 2 and store the remainder into an array or stack. If we store the remainder into an array then print it into reverse order. If we store the remainder into a stack then simply pop one by one element and print it.
Below is the java implementation of the above approach:
Java
// Java Program to Convert Integer Values into Binary  // Importing CLasses/Filesimport java.io.*;  public class GFG {    // Function to print binary number    static void printBinary(int[] binary, int id)    {        // Iteration over array        for (int i = id - 1; i >= 0; i--)            System.out.print(binary[i] + "");    }      // Function converting decimal to binary    public static void decimalToBinary(int num)    {        // Creating and assigning binary array size        int[] binary = new int[35];        int id = 0;          // Number should be positive        while (num > 0) {            binary[id++] = num % 2;            num = num / 2;        }          // Print Binary        printBinary(binary, id);    }      // Main Driver Code    public static void main(String[] args)    {        // Entered number to be convert into binary        int num = 45;          // Calling Our Above Function        decimalToBinary(num);    }}
101101
Using Stack By Creating Object Vector 
Java
// Java Program to Convert Integer Values into Binary  // Importing Classes/Filesimport java.io.*;import java.util.Stack;  public class GFG {        // Function to convert integer to binary    static void decimalToBinary(int num)    {        // Creating Stack Object Vector        Stack<Integer> st = new Stack<>();          // Number Should be positive        while (num > 0) {                        // Pushing numbers inside stack that            // are divisible by 2            st.push(num % 2);            // Dividing number by 2            num = num / 2;        }          // Checking condition whether stack is empty        while (!(st.isEmpty())) {                        // Printing binary number            System.out.print(st.pop());        }    }      // Main driver function    public static void main(String[] args)    {        // Entered number to be converted into binary        int num = 45;        decimalToBinary(num);    }}
101101
Java
// Java Program to Convert Integer Values into Binary  // Importing Classes/Filesimport java.io.*;  class GFG {    // Function converting decimal to binary    static void decimalToBinary(int num)    {        // Function to print integer to binary using        // inbuilt toBinaryString method        System.out.println(Integer.toBinaryString(num));    }      // Main driver function    public static void main(String[] args)    {        // Number to be converted into binary        int num = 45;          // Calling function        decimalToBinary(num);    }}
101101
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