BigInteger creation
In this chapter you will learn:
- How to create BigInteger from byte array
- How to create BigInteger from String
- How to use different radix to create BigInteger from String
- How to create BigInteger with random number
Create BigInteger from byte array
BigInteger(byte[] val)
Translates a byte array containing the two's-complement
binary representation of a BigInteger into a BigInteger.
The following code use new BigInteger(byte[] val) to create a BigInteger.
import java.math.BigInteger;
/*j ava2 s . c o m*/
public class Main {
public static void main(String[] argv) throws Exception {
// A negative value
byte[] bytes = new byte[] { (byte) 0xFF, 0x00, 0x00 }; // -65536
// A positive value
bytes = new byte[] { 0x1, 0x00, 0x00 }; // 65536
BigInteger bi = new BigInteger(bytes);
}
}
Create BigInteger from String
BigInteger(String val)
translates the decimal String representation of a BigInteger into a BigInteger.
The following code use new BigInteger(String val)to create a BigInteger.
import java.math.BigInteger;
/*j av a2 s . c o m*/
public class MainClass {
public static void main(String[] args) {
System.out.println("Here's Long.MAX_VALUE: " + Long.MAX_VALUE);
BigInteger bInt = new BigInteger("3419229223372036854775807");
System.out.println("Here's a bigger number: " + bInt);
System.out.println("Here it is as a double: " + bInt.doubleValue());
}
}
The code above generates the following result.
Use different radix to create BigInteger from String
BigInteger(String val, int radix)
translates the String representation of a BigInteger in the specified radix into a BigInteger.
You can set the radix for the string value passed in with
new BigInteger(String val, int radix).
import java.math.BigInteger;
//j a v a 2s .c o m
public class Main {
public static void main(String[] argv) throws Exception {
BigInteger bi = new BigInteger("4407760", 8);
}
}
Create BigInteger with random number
new BigInteger(int bitLength, int certainty, Random rnd)
creates a BigInteger with a random number
import java.math.BigInteger;
import java.security.SecureRandom;
/*from j a va 2 s . c om*/
public class Main {
public static void main(String[] args) throws Exception {
int bitLength = 512; // 512 bits
SecureRandom rnd = new SecureRandom();
int certainty = 90; // 1 - 1/2(90) certainty
BigInteger mod = new BigInteger(bitLength, certainty, rnd);
}
}
Next chapter...
What you will learn in the next chapter:
- How to add two BigInteger values together
- How to subtract one BigInteger with another BigInteger
- How to multiply two BigInteger values
- How ot divide one BigInteger from another BigInteger