Eighty-eight, base conversion (one method is common)

import java.math.BigInteger;

public class Main {
	public static void main(String[] args) {

		BigInteger b = new BigInteger("67", 10);
		
		System.out.println(b.toString(2));   //1000011
	}
}

Result: 1000011

Decimal to Binary

import java.math.BigInteger;

public class Main {
	public static void main(String[] args) {

		BigInteger b = new BigInteger("67", 8);
		
		System.out.println(b.toString(10));   //55
	}
}

Result: 55

Octal to Decimal

import java.math.BigInteger;

public class Main {
	public static void main(String[] args) {

		BigInteger b = new BigInteger("67", 16);
		
		System.out.println(b.toString(8));    //147
	}
}

Results: 147

Hexadecimal to Octal

        Through the above examples, it is found that there is no, you only need to modify the corresponding number to convert the number, and you don't need to memorize the cumbersome built-in functions.