Java 中的 Java.util.Random.nextInt()
原文:https://www . geesforgeks . org/Java-util-random-nextint-Java/
生成随机数本身具有很好的实用价值，通过函数的使用来实现它们可以证明是非常有用的。Java 用它的语言把整个库都献给了随机数，可见它在日常编程中的重要性。本文将讨论 nextInt()。
-
java.util.Random.nextInt() : The nextInt() is used to get the next random integer value from this random number generator’s sequence.
```java Declaration : public int nextInt() Parameters : NA Return Value : The method call returns the next integer number from the sequence Exception : NA
```
下面的例子展示了 java.util.Random.nextInt()的用法
```java // Java code to demonstrate the working // of nextInt() import java.util.*; public class NextInt1 { public static void main(String[] args) {
// create random object Random ran = new Random();
// generating integer int nxt = ran.nextInt();
// Printing the random Number System.out.println ("The Randomly generated integer is : " + nxt); } } ```
输出:
```java The Randomly generated integer is : -2052834321
```
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java.util.Random.nextInt(int n) : The nextInt(int n) is used to get a random number between 0(inclusive) and the number passed in this argument(n), exclusive.
```java Declaration : public int nextInt(int n) Parameters : n : This is the bound on the random number to be returned. Must be positive. Return Value : Returns a random number. between 0 (inclusive) and n (exclusive). Exception : IllegalArgumentException : This is thrown if n is not positive.
```
下面的例子展示了 java.util.Random.nextInt(int n)的用法
```java // Java code to demonstrate the working // of nextInt(n) import java.util.*; public class NextInt2 { public static void main(String args[]) {
// create random object Random ran = new Random();
// Print next int value // Returns number between 0-9 int nxt = ran.nextInt(10);
// Printing the random number // between 0 and 9 System.out.println ("Random number between 0 and 10 is : " + nxt); } } ```
输出:
```java Random number between 0 and 9 is : 4
```
Exception
IllegalArgumentException:当传递的参数不是正数时，就会出现这种情况。 举例说明当 n 不是正数时产生的异常:
// Java code to demonstrate the Exception
// of nextInt(n)
import java.util.*;
public class NextInt2 {
public static void main(String[] args)
{
// create random object
Random ran = new Random();
// generating number between 0 and -12345
// Raises Runtime error, as n is negative.
int nxt = ran.nextInt(-12345);
System.out.println
("Generated Random number is : " + nxt);
}
}
运行时错误:
Exception in thread "main" java.lang.IllegalArgumentException: bound must be positive
at java.util.Random.nextInt(Random.java:388)
at NextInt2.main(NextInt2.java:14)
实际应用
生成随机数有许多应用，无论是彩票、赌博还是小规模游戏。下面演示了一个小骰子游戏，其中一个 6 马克的骰子由两个玩家投掷，一个人获得 30 分，获胜。
// Java code to demonstrate the Application
// of nextInt(n)
import java.util.*;
public class NextIntAppli {
public static void main(String[] args)
{
int sum = 0, sum1 = 0, count = 0, count1 = 0;
int turn = 0;
// creating random object
Random ran = new Random();
int flag = 0;
while (true) {
if (turn % 2 == 0) {
int p1 = ran.nextInt(6);
sum += p1;
System.out.printf
("Player 1 after turn %d is : %d\n", turn, sum);
}
else {
int p2 = ran.nextInt(6);
sum1 += p2;
System.out.printf
("Player 2 after turn %d is : %d\n", turn, sum1);
}
if (sum >= 30) {
flag = 1;
break;
}
if (sum1 >= 30) {
flag = 2;
break;
}
turn++;
}
if (flag == 1)
System.out.println("\nPlayer 1 WON!!");
else
System.out.println("\nPlayer 2 WON!!");
}
}
输出:
Player 1 after turn 0 is : 0
Player 2 after turn 1 is : 4
Player 1 after turn 2 is : 2
Player 2 after turn 3 is : 9
Player 1 after turn 4 is : 5
Player 2 after turn 5 is : 9
Player 1 after turn 6 is : 6
Player 2 after turn 7 is : 14
Player 1 after turn 8 is : 8
Player 2 after turn 9 is : 18
Player 1 after turn 10 is : 12
Player 2 after turn 11 is : 21
Player 1 after turn 12 is : 13
Player 2 after turn 13 is : 26
Player 1 after turn 14 is : 18
Player 2 after turn 15 is : 29
Player 1 after turn 16 is : 18
Player 2 after turn 17 is : 34
Player 2 WON!!
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