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In this article Xiaobian for you to introduce in detail "java generates random integers how to specify the range", the content is detailed, the steps are clear, the details are handled properly, I hope this "java generates random integers how to specify the range" article can help you solve your doubts, the following follow the editor's ideas slowly in-depth, together to learn new knowledge.

The operating environment of this tutorial: windows7 system, java10 version, DELL G3 computer.

1. Math.random () produces a random return value of 0-1, which is greater than or equal to 0.0 and less than 1.0.

For example: 0.5105802498623931.

Taking advantage of this feature, the random quantity in the following specific range is derived:

(1) generate a random integer from 0 to n, that is, return the value [0Magne]

Int num= (int) (Math.random () * (nasty 1)

(2) generate a random integer from a to b, that is, return the value [aforme b]

Int num=a+ (int) (Math.random () * (b-a+1))

2. Use the nextInt (intorigin,intbound) method of java.util.concurent.ThreadLocalRandom class.

The returned random quantity ranges from origin (inclusive) to bound (excluding)

For example, a number of 10 (inclusive)-99 (inclusive) is generated as follows:

Int randomNum = ThreadLocalRandom.current (). NextInt (10, 99 + 1); what are the collection classes in Java? the collections in Java are mainly divided into four categories:

1. List list: ordered and repeatable

2. Queue queue: orderly and repeatable

3. Set collection: non-repeatable

4. Map mapping: unordered, key unique, value not unique.

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