Manually convert an integer into BINARY, HEXADECIMAL, and OCTAL............
Java Example Code

IntegerToBinary.java
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import java.io.*;
import java.lang.*;

public class IntegerToBinary {
public static void main(String[] args) throws IOException{
BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the integer value!");
String s = read.readLine();
int i = Integer.parseInt(s);
String by = Integer.toBinaryString(i);
System.out.println("Inter to Binary: " + by);
}
}


IntegerToHexa.java

import java.io.*;
import java.lang.*;

public class IntegerToHexa{
public static void main(String[] args) throws IOException{
BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the integer value:");
String hex = read.readLine();
int i = Integer.parseInt(hex);
String hex1 = Integer.toHexString(i);
System.out.println("Interger to Hexa: " + hex1);
}
}


IntegerToOctal.java

import java.io.*;
import java.lang.*;

public class IntegerToOctal{
public static void main(String[] args) throws IOException{
BufferedReader buff = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the integer value:");
String s = buff.readLine();
int value = Integer.parseInt(s);
String str = Integer.toString(value,8);
System.out.println("Interger to Octal:=" + str);
}
}