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# Random numbers

## Common

### Math.random

```Java
double d = Math.random();
```

### java.util.Random

```Java
Random random = new Random();
int i = random.nextInt();
random.ints(0, 1000).limit(7).forEach(System.out::println);
random.ints(7, 0, 1000).forEach(System.out::println);
```

### ThreadLocalRandom

```Java
Random random = ThreadLocalRandom.current();
int randomNumber = random.nextInt();
int number = 1 + random.nextInt(10);

```

* backed by Random class

## Seed Value

* this is used to generate a predicatable set of numbers for the random generators

## Non predicatable

* should use for cryptographic use cases ie passwords
* java.security.SecureRandom

```java
SecureRandom secureRandom = new SecureRandom();
double strongRandomNumber = secureRandom.nextDouble();
```

## Links

* <https://www.happycoders.eu/java/random-number/>