Java 8 Random and SecureRandom Changes Example
December 23, 2014
java.util.Random
Random class generates pseudorandom numbers. For each call of the instance, a pseudorandom number is returned. Random class is thread safe. Random class has some new methods to support java 8.ints: returns integer values as IntStream.
longs: returns long values as LongStream
doubles : returns double values as DoubleStream
Find the example to generate a password.
RandomDemo.java
package com.concretepage;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.stream.IntStream;
public class RandomDemo {
private static final List<Integer> VALID_PWD_CHARS = new ArrayList<>();
static {
IntStream.rangeClosed('0', '9').forEach(VALID_PWD_CHARS::add); // 0-9
IntStream.rangeClosed('a', 'z').forEach(VALID_PWD_CHARS::add); // a-z
}
public static void main(String[] args) {
int passwordLength = 8;
System.out.println("---Generated Password---");
for(int i=0;i<5;i++) {
new Random().ints(passwordLength, 0, VALID_PWD_CHARS.size())
.map(VALID_PWD_CHARS::get).forEach(s -> System.out.print((char) s));
System.out.println();
}
}
}
---Generated Password--- 6mx3dunz teuf505p 03nym5w3 zez006fc y9q0rbs3
java.security.SecureRandom
SecureRandom is cryptographically strong number generator (RNG). SecureRandom extends Random class and is enriched by new methods added in java 8. Find the example for SecureRandom.SecureRandomDemo.java
package com.concretepage;
import java.security.SecureRandom;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.IntStream;
public class SecureRandomDemo {
private static final List<Integer> VALID_PWD_CHARS = new ArrayList<>();
static {
IntStream.rangeClosed('0', '9').forEach(VALID_PWD_CHARS::add); // 0-9
IntStream.rangeClosed('A', 'Z').forEach(VALID_PWD_CHARS::add); // A-Z
IntStream.rangeClosed('a', 'z').forEach(VALID_PWD_CHARS::add); // a-z
IntStream.rangeClosed('!', '*').forEach(VALID_PWD_CHARS::add); // !-*
}
public static void main(String[] args) {
int passwordLength = 8;
System.out.println("---Generated Password---");
for(int i=0;i<5;i++) {
new SecureRandom().ints(passwordLength, 0, VALID_PWD_CHARS.size())
.map(VALID_PWD_CHARS::get).forEach(s -> System.out.print((char) s));
System.out.println();
}
}
}
---Generated Password--- Qq2R%SsQ 7PjxGxkO xkMgQq2h dljs4*w% 55"tSGJ5
