在 Java 中生成随机数
原文:https://www . geesforgeks . org/generating-random-numbers-in-Java/
Java 提供了三种使用下面列出的一些内置方法和类生成随机数的方法:
- java.util.Random 类
- Math.random 方法:可以生成双式随机数。
- 线程本地随机类
- 为了使用这个类生成随机数，我们必须首先创建这个类的一个实例，然后使用那个实例调用诸如 nextInt()、nextDouble()、nextLong()等方法。
- 我们可以使用这个类生成整数、浮点、双精度、长整型的随机数。
-
We can pass arguments to the methods for placing an upper bound on the range of the numbers to be generated. For example, nextInt(6) will generate numbers in the range 0 to 5 both inclusive.
```java // A Java program to demonstrate random number generation // using java.util.Random; import java.util.Random;
public class generateRandom{
public static void main(String args[]) { // create instance of Random class Random rand = new Random();
// Generate random integers in range 0 to 999 int rand_int1 = rand.nextInt(1000); int rand_int2 = rand.nextInt(1000);
// Print random integers System.out.println("Random Integers: "+rand_int1); System.out.println("Random Integers: "+rand_int2);
// Generate Random doubles double rand_dub1 = rand.nextDouble(); double rand_dub2 = rand.nextDouble();
// Print random doubles System.out.println("Random Doubles: "+rand_dub1); System.out.println("Random Doubles: "+rand_dub2); } } ```
输出:
```java Random Integers: 547 Random Integers: 126 Random Doubles: 0.8369779739988428 Random Doubles: 0.5497554388209912
```
2) Math.random() ```java // Java program to demonstrate working of // Math.random() to generate random numbers import java.util.*;
public class generateRandom { public static void main(String args[]) { // Generating random doubles System.out.println("Random doubles: " + Math.random()); System.out.println("Random doubles: " + Math.random()); } } ```
输出:
```java Random doubles: 0.13077348615666562 Random doubles: 0.09247016928442775
```
3) java.util.concurrent.ThreadLocalRandom class ```java // Java program to demonstrate working of ThreadLocalRandom // to generate random numbers. import java.util.concurrent.ThreadLocalRandom;
public class generateRandom { public static void main(String args[]) { // Generate random integers in range 0 to 999 int rand_int1 = ThreadLocalRandom.current().nextInt(); int rand_int2 = ThreadLocalRandom.current().nextInt();
// Print random integers System.out.println("Random Integers: " + rand_int1); System.out.println("Random Integers: " + rand_int2);
// Generate Random doubles double rand_dub1 = ThreadLocalRandom.current().nextDouble(); double rand_dub2 = ThreadLocalRandom.current().nextDouble();
// Print random doubles System.out.println("Random Doubles: " + rand_dub1); System.out.println("Random Doubles: " + rand_dub2);
// Generate random booleans boolean rand_bool1 = ThreadLocalRandom.current().nextBoolean(); boolean rand_bool2 = ThreadLocalRandom.current().nextBoolean();
// Print random Booleans System.out.println("Random Booleans: " + rand_bool1); System.out.println("Random Booleans: " + rand_bool2); } } ```
输出:
```java Random Integers: 536953314 Random Integers: 25905330 Random Doubles: 0.7504989954390163 Random Doubles: 0.7658597196204409 Random Booleans: false Random Booleans: true
```
参考文献: https://docs.oracle.com
本文由 哈什·阿加瓦尔 供稿。如果你喜欢 GeeksforGeeks 并想投稿，你也可以使用contribute.geeksforgeeks.org写一篇文章或者把你的文章邮寄到 contribute@geeksforgeeks.org。看到你的文章出现在极客博客主页上，帮助其他极客。
如果你发现任何不正确的地方，或者你想分享更多关于上面讨论的话题的信息，请写评论。
版权属于：月萌API www.moonapi.com，转载请注明出处
