Question

我测试了随机数生成器，它在应用程序之外工作正常。这是一段相当标准的代码。我创建了getter和setter，并且NetBeans没有抱怨传递给应用程序的任何内容，但是随机数应该是“0”。我想更多地了解getter和setter以及类。我可能指错了。

//这是类代码

public class RandomGen {

    int minSeed = 100;
    int maxSeed = 999;
    int num;

    public static void RandomNum(int minSeed, int maxSeed) {
        Random rand = new Random();
        int num = rand.nextInt(maxSeed - minSeed) + 1;
    }

    public void setMin(int minSeed) {
        this.minSeed = minSeed;
    }

    public void setMax(int maxSeed) {
        this.maxSeed = maxSeed;
    }

    public int getNum() {
        return num;
    }
}

这是我的应用程序中main的代码

RandomGen rnumber = new RandomGen();
int rnum = rnumber.getNum();
int bigSeed = rnumber.maxSeed;
int smallSeed = rnumber.minSeed;

System.out.println("Random Number =  " + rnum);
System.out.println("MaxSeed = " + bigSeed);
System.out.println("MinSeed = " + smallSeed);

这是打印的退货

Random Number =  0
MaxSeed = 999
MinSeed = 100

Answer 1

您已创建了一个局部变量，因此请使用全局

num = rand.nextInt(maxSeed - minSeed) + 1;

根据您的代码，您需要调用static方法来初始化num以及

RandomGen rnumber = new RandomGen();
RandomGen.RandomNum(rnumber.minSeed, rnumber.maxSeed);
//^^^^^^^^^^^^^^^^^^^^^
int rnum = rnumber.getNum();
int bigSeed = rnumber.maxSeed;
int smallSeed = rnumber.minSeed;

注意：构造函数不能是static，不能有任何返回类型

static int num; // global to class, different from the `num` inside RandomNum

public static void RandomNum(int minSeed, int maxSeed)
 {
    Random rand = new Random();
    // local variable
    // changes here, can only be seen inside RandomNum method
    //int num = rand.nextInt(maxSeed - minSeed) + 1;
    num = rand.nextInt(maxSeed - minSeed) + 1;

 }

Answer 2

首先

static int num; // must also be static

第二

public static void RandomNum(int minSeed, int maxSeed)
 {
    Random rand = new Random();
    num = rand.nextInt(maxSeed - minSeed) + 1; // remove the declaration you try to make it local variable 

 }

Answer 3

这是不正确的。

试试这个：

import java.util.Random;

public class RandomGen {

    private Random random;
    private int minRange;
    private int maxRange;

    public static void main(String[] args) {
        int minRange = (args.length > 0) ? Integer.parseInt(args[0]) : 100;
        int maxRange = (args.length > 1) ? Integer.parseInt(args[1]) : 200;
        int numValues = (args.length > 2) ? Integer.parseInt(args[2]) : 10;
        RandomGen randomGen = new RandomGen(minRange, maxRange);
        for (int i = 0; i < numValues; ++i) {
            System.out.println(randomGen.getNextIntInRange());
        }
    }

    public RandomGen(int minRange, int maxRange) {
        this(minRange, maxRange, null);
    }

    public RandomGen(int minRange, int maxRange, Long seed) {
        this.minRange = minRange;
        this.maxRange = maxRange;
        this.random = (seed == null) ? new Random() : new Random(seed);
    }

    public int getNextIntInRange() {
        return this.minRange + this.random.nextInt(this.maxRange-this.minRange)+1;
    }
}

随机数生成器在Java中返回“0”

3 个答案: