随机数生成器:主要是如何停止数字的重复.爪哇 [英] Random Number Generator: mainly how to stop repetition of numbers. Java
问题描述
所以我正在开发一个 OOP 程序，该程序旨在通过使用确保没有重复数字的随机数生成器来创建 50 个唯一数字.我有随机部分，我正在使用一种额外的方法来交换数字，但我不知道如果它们已经被使用，我不知道只交换数字，我希望这是可以理解的.
So I'm working on an OOP program that is meant to create 50 unique numbers, by using a random number generator that ensures no repeating numbers. I have the random part down and I'm using an extra method which swaps the numbers but I don't know to only swap number if they are already used, I hope this is understandable.
import java.util.Random;
public class Project_1
{
public static void main(String[] args)
{
Random rand = new Random();
int a[][] = new int[11][6];
for (int i = 1; i <= 10; i++) //row of values which fill in Student number
{
System.out.print("Student " + i + ":");
System.out.print("\t");
for (int j = 1; j <= 5; j++) //j is limited up to 5 columns
{
a[i][j] = 1 + rand.nextInt(50);
CheckNumbers(a[i][j]); //input of the checkNumbers method
System.out.print(a[i][j] + "\t"); // meaning that the numbers fill out according to table coordinates
}
System.out.println();
}
}
public static void CheckNumbers(int[] x, int[] y)
{
int temp;
for (int j = 0; j < 50; j++) //j must start at 1??? and we have 50 iterations, so countercontrolled to 50?
{
temp = x[i]; //this can be used to swap the numbers
x[i] = y[i];
y[i] = temp;
}
}
}
这是我的程序，如果在没有输入 CheckNumbers 方法的情况下运行，我的答案是
This is my program and if ran without the input of the CheckNumbers method my answer was
----jGRASP exec: java Project_1
Student 1: 8 35 8 5 40
Student 2: 46 3 44 40 8
Student 3: 27 47 28 11 3
Student 4: 30 25 43 8 34
Student 5: 3 12 45 6 5
Student 6: 19 37 33 14 14
Student 7: 9 31 6 39 32
Student 8: 16 6 23 28 31
Student 9: 19 34 49 42 11
Student 10: 26 3 17 16 15
----jGRASP: operation complete.
然而，正如你看到的 8 是重复的(可能还有其他数字)，所以我放入了 CheckNumbers 方法来阻止它，但我有一个错误填充的编译消息......所以我假设我的 CheckNumbers 中有很多错误，所以我也需要很大的帮助.
However as you see 8 is repeated (among may other numbers) so I put in the CheckNumbers method to stop it but I have an error filled compile message... so I am assuming that I have many errors in my CheckNumbers, so I need major help with that too.
谢谢大家的帮助！！！！
Thank you all for your help!!!!
推荐答案
我不会纠正你的方法.但如果你想创建一个不重复的随机，创建你自己的自定义类.
I'm not going to correct your methods. But if you want to create a random without repeating, create your own custom class.
import java.util.BitSet;
import java.util.Random;
/**
* Random number generator without repeat in the given range at construction time.
*
* @author martijn
*/
public class NoRepeatRandom {
private Random random;
private BitSet used;
private int max;
/**
* Creates new instance of NoRepeatRandom, with the range <code>[0-max[</code>.
* @param max the maximum for the range
* @param seed the seed for the underlying {@link java.util.Random}
*/
public NoRepeatRandom(int max, long seed)
{
this.max = max;
this.used = new BitSet(max);
this.random = new Random(seed);
}
/**
* Creates new instance of NoRepeatRandom, with the range <code>[0-max[</code>.<br />
* <code>System.currentTimeMillis()</code> is used as seed for the underlying {@link java.util.Random}
* @param max the maximum for the range
*/
public NoRepeatRandom(int max)
{
this(max, System.currentTimeMillis());
}
/**
* Gives the next random number
* @return a new random number. When finished it returns -1.
*/
public int next()
{
if (isFinished())
{
return -1;
}
while (true)
{
int r = random.nextInt(max);
if (!used.get(r))
{
used.set(r);
return r;
}
}
}
/**
* Tells if the random generator has finished. Which means that all number in the range
* [0-max[ are used.
* @return true if all numbers are used, otherwise false.
*/
public boolean isFinished()
{
return max == used.cardinality();
}
/**
* Sets all the numbers in the range [0-max[ to unused. Which means that all the numbers
* can be reused.
*/
public void reset()
{
used.clear();
}
/**
*
* @return the maximum.
*/
public int getMax()
{
return max;
}
}
用法:
NoRepeatRandom myRandom = new NoRepeatRandom(50);
for (int i = 0; i < myRandom.getMax(); ++i)
System.out.println(myRandom.next());
添加了 JavaDoc！！
这篇关于随机数生成器:主要是如何停止数字的重复.爪哇的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
