Question

我尝试在这里寻找类似的东西，但未能找到它，也许使用错误的关键字让我知道，但这是交易。

我对java很新，想自己创造一些有用的东西。我的想法是在一个范围内创建一个随机数字选择器。所以，让我们说范围是1-50，我希望在这个范围内有5个随机数，它们必须完全不同。我以前曾经使用过Random，但不确定我做错了什么，这是我到目前为止的代码，如果可能的话，请把我推向正确的方向。我想用数字创建一个数组或列表，还是有更好的方法来做到这一点？

import java.util.Scanner;
import java.util.Random;

public class Randomizer {
    static Random rnd = new Random();
    static int rnd(int a, int b){
        return a+rnd.nextInt(b-a+1);
    }

    public static void nPicker(){
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter start of range: ");
        int start = sc.nextInt();
        System.out.println("Enter end of range: ");
        int end = sc.nextInt();
        System.out.println("Enter amount of numbers to pick: ");
        int c = sc.nextInt();
        sc.close(); 
        rnd(start,end);
        int[] randomArrays = new int[c];

        for(int i = 0; i>randomArrays.length; i++){
            randomArrays.add();
        }
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        nPicker();
    }

}

抱歉，如果我的代码很乱。目前，我甚至无法将随机数添加到数组中

Answer 1

试试这个，我确实向你解释了代码中的注释有什么问题，请阅读它们。

import java.util.Scanner;
import java.util.Random;

public class Randomizer {

static int[] randomArrays; // You need to declare the vector as an instance variable, otherwise it will disappear when the method it's done. 

static Random rnd = new Random();

static int rnd(int a, int b){
    return a+rnd.nextInt(b-a+1);
}

public static void nPicker(){
    Scanner sc = new Scanner(System.in);
    System.out.println("Enter start of range: ");
    int start = sc.nextInt();
    System.out.println("Enter end of range: ");
    int end = sc.nextInt();
    System.out.println("Enter amount of numbers to pick: ");
    int c = sc.nextInt();
    sc.close(); 
    randomArrays = new int[c];

    for(int i = 0; i<randomArrays.length; i++){ // The condition was wrong


        int numberToAdd = rnd(start,end);

        randomArrays[i] = numberToAdd; //You are not using an ArrayList, vector has not the method add(), you have to add new element to the vector throughout its index
    }
}

public static void main(String[] args) {

   Randomizer rdm = new Randomizer();

   rdm.nPicker();

   for(int number:rdm.randomArrays) {

        System.out.println(number);

   }  

}

}

Answer 2

感谢大家的建议和提示。最后我想我设法用下面的代码得到了我想要的代码如果你在这个方法中看到错误，或者它有一种在java中不允许的方式，请告诉我。

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好的，我最后改变了循环如下：

import java.util.Scanner;
import java.util.Random;
import java.util.ArrayList;
import java.util.List;

public class Randomizer {
    static Random rnd = new Random();
    static int rnd(int a, int b){
        return a+rnd.nextInt(b-a+1);
    }

    public static void nPicker(){
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter start of range: ");
        int start = sc.nextInt();
        System.out.println("Enter end of range: ");
        int end = sc.nextInt();
        System.out.println("Enter amount of numbers to pick: ");
        int c = sc.nextInt();
        sc.close(); 
        List randomnumbers = new ArrayList();

        for(int i = 0; i<c; i++){
            int numb = rnd(start,end);
            if(randomnumbers.contains(numb)){
                break;
            }else{
                randomnumbers.add(numb);
            }

        }
        randomnumbers.forEach(System.out::println); 
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        nPicker();
    }

}

似乎这样工作正常

在一定范围内创建一个简单的java随机数字选择

2 个答案: