不重复上一个随机数的随机数

Question

我正在 Java swing 中开发一个简单的程序，当您单击一个按钮时，它会从数组中随机选择一个单词。问题是我不想在再次单击按钮后生成相同的东西。例如，你点击按钮，它从数组中生成单词“甜甜圈”，你再次点击，它再次生成甜甜圈。我想避免之后直接生成相同的东西。

代码如下：


import javax.swing.*;
import java.awt.*;
import java.util.Random;
import java.awt.event.*;

class Main implements ActionListener{
  JFrame f = new JFrame("ℂ ");
  Random r = new Random();
  JButton generate = new JButton("Generate");
  JButton clear = new JButton("Clear");

  JLabel characterClass = new JLabel("Style", JLabel.CENTER);
  JLabel characterClass2 = new JLabel("Race", JLabel.CENTER);
  JLabel characterClass3 = new JLabel("Weapon", JLabel.CENTER);
  
  JLabel newGenerate = new JLabel("?", JLabel.CENTER);
  JLabel newGenerate2 = new JLabel("?", JLabel.CENTER);
  JLabel newGenerate3 = new JLabel("?", JLabel.CENTER);

  Color custBlue = new Color(10, 63, 250);
  Color custOrange = new Color(251,167,88);
  Color saturatedCustOrange = new Color(254, 127, 46);
  ImageIcon wheel = new ImageIcon("images/loading_wheel.gif");
  JLabel img = new JLabel(wheel);
  ImageIcon back_image = new ImageIcon("images/back_ground.png");
  JLabel img2 = new JLabel(back_image);

  String[] style = {"<html><p align='center'>Steampunk</p></html>", "<html><p align='center'>Sci-Fi</p></html>", "<html><p align='center'>Medieval</p></html>", "<html><p align='center'>Imprisoned</p></html>", "<html><p align='center'>Superpowered</p></html>", "<html><p align='center'>Villainous</p></html>", "<html><p align='center'>Primal</p></html>", "<html><p align='center'>Musical</p></html>", "<html><p align='center'>Aquatic</p></html>", "<html><p align='center'>Undead</p></html>"};

  String[] race = {"<html><p align='center'>Sorcerer</p></html>", "<html><p align='center'>Alien</p></html>", "<html><p align='center'>Knight</p></html>", "<html><p align='center'>Orc</p></html>", "<html><p align='center'>Elf</p></html>", "<html><p align='center'>Bear</p></html>", "<html><p align='center'>Human</p></html>", "<html><p align='center'>Vampire</p></html>", "<html><p align='center'>Werewolf</p></html>", "<html><p align='center'>Dwarf</p></html>"};

  String[] weapon = {"<html><p align='center'>Bow<br />And Arrow</p></html>", "<html><p align='center'>Blade</p></html>", "<html><p align='center'>Gun</p></html>", "<html><p align='center'>Nunchucks</p></html>", "<html><p align='center'>Shield</p></html>", "<html><p align='center'>Bomb</p></html>", "<html><p align='center'>Claws</p></html>", "<html><p align='center'>Mace</p></html>", "<html><p align='center'>Axe</p></html>", "<html><p align='center'>Staff</p></html>"};
  
  public static void main(String[] args) {
    Main o = new Main();
    o.gui();
  }
  public void gui(){
    f.setSize(500, 400);
    
    this.newGenerate.setBounds(132,107, 180, 40);
    newGenerate.setFont(new Font("Arial", Font.BOLD, 20));
    this.newGenerate.setForeground(saturatedCustOrange);
    f.add(this.newGenerate);

    this.newGenerate2.setBounds(304,107, 180, 40);
    newGenerate2.setFont(new Font("Arial", Font.BOLD, 20));
    this.newGenerate2.setForeground(saturatedCustOrange);
    f.add(this.newGenerate2);

    this.newGenerate3.setBounds(218,250, 180, 40);
    newGenerate3.setFont(new Font("Arial", Font.BOLD, 20));
    this.newGenerate3.setForeground(saturatedCustOrange);
    f.add(this.newGenerate3);

    characterClass.setBounds(132,50, 180, 40);
    characterClass.setFont(new Font("Arial", Font.BOLD, 20));
    this.characterClass.setForeground(saturatedCustOrange);
    f.add(this.characterClass);

    characterClass2.setBounds(304,50, 180, 40);
    characterClass2.setFont(new Font("Arial", Font.BOLD, 20));
    this.characterClass2.setForeground(saturatedCustOrange);
    f.add(this.characterClass2);

    characterClass3.setBounds(218,192, 180, 40);
    characterClass3.setFont(new Font("Arial", Font.BOLD, 20));
    this.characterClass3.setForeground(saturatedCustOrange);
    f.add(this.characterClass3);

    this.generate.setBounds(50, 240, 120, 40);
    generate.setFont(new Font("Arial", Font.BOLD, 16));
    this.generate.setForeground(custOrange);
    this.generate.setBackground(custBlue);
    this.generate.addActionListener(this);
    f.add(this.generate);

    this.clear.setBounds(50, 290, 120, 40);
    clear.setFont(new Font("Arial", Font.BOLD, 16));
    this.clear.setForeground(custOrange);
    this.clear.setBackground(custBlue);
    this.clear.addActionListener(this);
    f.add(this.clear);

    
    img.setBounds(0, -10,500,400);
    f.add(img);

    img2.setBounds(0, -10,500,400);
    f.add(img2);
       
    f.setLayout(null);
    f.setVisible(true);
  }
  public void actionPerformed(ActionEvent e){
  if(e.getSource() == this.clear){
    img.setVisible(true);
    this.newGenerate.setText("?");
    this.newGenerate2.setText("?");
    this.newGenerate3.setText("?");
  }
  else{
    this.newGenerate.setText(this.returnStyle());
    this.newGenerate2.setText(this.returnRace());
    this.newGenerate3.setText(this.returnWeapon());
    img.setVisible(false); 
  }
}

  public String returnStyle() {
    int ranNum = r.nextInt(this.style.length);

    return this.style[ranNum];
 }

  public String returnRace() {
    int ranNum = r.nextInt(this.race.length);
    
    return this.race[ranNum];
 }

  public String returnWeapon() {
    int ranNum = r.nextInt(this.weapon.length);
    
    return this.weapon[ranNum];
 }

}

如果混淆，程序会生成一个字符。它随机混合角色风格（如中世纪或 sci-fi）、种族（如人类或吸血鬼）和武器（如 blade 或斧头）。

我特别需要这部分的帮助，我最好需要用循环来完成，因为这是我能想到的唯一方法来处理这个循环（我的最终项目需要它。）

public String returnStyle() {
    int ranNum = r.nextInt(this.style.length);

    return this.style[ranNum];
}

Answer 1

基本上你可以这样做：

ArrayList<String> fruits = new ArrayList<>(Arrays.asList("banana", "apple", "orange","grape","watermelon"));
Random r = new Random();
while(fruits.size()>0) {
   int random = r.nextInt(fruits.size());
   System.out.println(fruits.get(randomInt));
   fruits.remove(randomInt);
}

创建一个列表。
生成一个随机索引，弹出这个索引中的元素，重复。

Answer 2

如果你希望它能够重复结果，而不是它产生的最后一个结果，你可以存储它产生的最后一个结果并检查新的是否相同。如果是，则生成另一个。以 ATP 的回答为例并对其进行修改以实现此目的，它将如下所示：

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class RandomGenerator
{
    public static void main (String[] args) throws java.lang.Exception
    {
        ArrayList<String> fruits = new ArrayList<>(Arrays.asList("banana", "apple", "orange","grape","watermelon"));
        Random r = new Random();
        int previousRandom = -1;
        int random = r.nextInt(fruits.size());
        System.out.println("double size: " + 2 * fruits.size());
        for (int i = 0; i < 2 * fruits.size(); i++) {
            if (random == previousRandom) {
                random = r.nextInt(fruits.size());
                i = i -1;
            } else {
                System.out.println(fruits.get(random));
                previousRandom = random;
            }
        }
    }
}

如果您不希望它重复任何结果，并且只生成尽可能多的结果，那么 ATP 的答案就可以了。

Answer 3

对于“不同”的方法，您可以使用 Collections#shuffle 随机化 List 个值

首先，您需要...

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

接下来，您需要定义一系列“随机”List。这使我们可以使用更简单的方法来获取下一个随机值，同时保持对“原始”值的引用，例如...

    private String[] masterStyles = {"<html><p align='center'>Steampunk</p></html>", "<html><p align='center'>Sci-Fi</p></html>", "<html><p align='center'>Medieval</p></html>", "<html><p align='center'>Imprisoned</p></html>", "<html><p align='center'>Superpowered</p></html>", "<html><p align='center'>Villainous</p></html>", "<html><p align='center'>Primal</p></html>", "<html><p align='center'>Musical</p></html>", "<html><p align='center'>Aquatic</p></html>", "<html><p align='center'>Undead</p></html>"};
    private String[] masterRaces = {"<html><p align='center'>Sorcerer</p></html>", "<html><p align='center'>Alien</p></html>", "<html><p align='center'>Knight</p></html>", "<html><p align='center'>Orc</p></html>", "<html><p align='center'>Elf</p></html>", "<html><p align='center'>Bear</p></html>", "<html><p align='center'>Human</p></html>", "<html><p align='center'>Vampire</p></html>", "<html><p align='center'>Werewolf</p></html>", "<html><p align='center'>Dwarf</p></html>"};
    private String[] masterWeapons = {"<html><p align='center'>Bow<br />And Arrow</p></html>", "<html><p align='center'>Blade</p></html>", "<html><p align='center'>Gun</p></html>", "<html><p align='center'>Nunchucks</p></html>", "<html><p align='center'>Shield</p></html>", "<html><p align='center'>Bomb</p></html>", "<html><p align='center'>Claws</p></html>", "<html><p align='center'>Mace</p></html>", "<html><p align='center'>Axe</p></html>", "<html><p align='center'>Staff</p></html>"};
    
    private List<String> randomStyles = new ArrayList<>(8);
    private List<String> randomRaces = new ArrayList<>(8);
    private List<String> randomWeapons = new ArrayList<>(8);

然后，您可以将 returnXxx 方法修改为 return 下一个随机值，除非，如果随机 List isEmpty，则用原始值填充它值然后 shuffle 它，例如...

    public String returnStyle() {
        if (randomStyles.isEmpty()) {
            randomStyles.addAll(Arrays.asList(masterStyles));
            Collections.shuffle(randomStyles);
        }
        return randomStyles.remove(0);
    }

    public String returnRace() {
        if (randomRaces.isEmpty()) {
            randomRaces.addAll(Arrays.asList(masterRaces));
            Collections.shuffle(randomRaces);
        }
        return randomRaces.remove(0);
    }

    public String returnWeapon() {
        if (randomWeapons.isEmpty()) {
            randomWeapons.addAll(Arrays.asList(masterWeapons));
            Collections.shuffle(randomWeapons);
        }
        return randomWeapons.remove(0);
    }

这保证了 List 中的值只有在您使用了原始 List

中的所有值后才会开始重复

然后我们可以将概念封装到 class 中以使其更容易，例如...

public class RandomList<Value> {
    private List<Value> masterValues;
    private List<Value> randomValues;
    
    public RandomList(Value[] masterValues) {
        this(Arrays.asList(masterValues));
    }

    public RandomList(List<Value> masterValues) {
        this.masterValues = masterValues;
        randomValues = new ArrayList<>(masterValues);
        Collections.shuffle(randomValues);
    }
    
    public Value next() {
        if (randomValues.isEmpty()) {
            randomValues.addAll(masterValues);
            Collections.shuffle(randomValues);
        }
        return randomValues.remove(0);
    }
    
    public Value nextOrNull() {
        if (randomValues.isEmpty()) {
            return null;
        }
        return randomValues.remove(0);
    }
}

这会将您的代码更改为...

    private RandomList<String> randomStyles = new RandomList<>(new String [] {"<html><p align='center'>Steampunk</p></html>", "<html><p align='center'>Sci-Fi</p></html>", "<html><p align='center'>Medieval</p></html>", "<html><p align='center'>Imprisoned</p></html>", "<html><p align='center'>Superpowered</p></html>", "<html><p align='center'>Villainous</p></html>", "<html><p align='center'>Primal</p></html>", "<html><p align='center'>Musical</p></html>", "<html><p align='center'>Aquatic</p></html>", "<html><p align='center'>Undead</p></html>"});
    private RandomList<String> randomRaces = new RandomList<>(new String [] {"<html><p align='center'>Sorcerer</p></html>", "<html><p align='center'>Alien</p></html>", "<html><p align='center'>Knight</p></html>", "<html><p align='center'>Orc</p></html>", "<html><p align='center'>Elf</p></html>", "<html><p align='center'>Bear</p></html>", "<html><p align='center'>Human</p></html>", "<html><p align='center'>Vampire</p></html>", "<html><p align='center'>Werewolf</p></html>", "<html><p align='center'>Dwarf</p></html>"});
    private RandomList<String> randomWeapons = new RandomList<>(new String [] {"<html><p align='center'>Bow<br />And Arrow</p></html>", "<html><p align='center'>Blade</p></html>", "<html><p align='center'>Gun</p></html>", "<html><p align='center'>Nunchucks</p></html>", "<html><p align='center'>Shield</p></html>", "<html><p align='center'>Bomb</p></html>", "<html><p align='center'>Claws</p></html>", "<html><p align='center'>Mace</p></html>", "<html><p align='center'>Axe</p></html>", "<html><p align='center'>Staff</p></html>"});

和您的 returnXxx 方法，例如...

    public String returnStyle() {
        return randomStyles.next();
    }

    public String returnRace() {
        return randomRaces.next();
    }

    public String returnWeapon() {
        return randomWeapons.next();
    }

它更简单、更清晰，并且删除了所有重复代码……但是，这可能比您现在更“高级”一点，但请记住一些事情

不重复上一个随机数的随机数

Random that doesn’t repeat the last random

java

arrays

random

swing