如何生成1到8的随机数而不重复？

Question

我使用 Java AWT 创建了以下随机拼图。在程序开始时，如您所见，所有数字都是有序的。我想生成随机数而不重复。这该怎么做？我应该使用 Random class 吗？

import java.awt.*;
import java.awt.event.*;
class Puzzle extends Frame implements ActionListener
{
    Button b1,b2,b3,b4,b5,b6,b7,b8,b9;
    Puzzle()
    {
        setTitle("Shuffle");
        setSize(500,500);
        setLayout(new GridLayout(3,3));
        setVisible(true);
        Font f=new Font("Arial",Font.BOLD,100);

        b1=new Button("1");
                            b1.setFont(f);
                            b1.addActionListener(this);
        b2=new Button("2");
                            b2.setFont(f);
                            b2.addActionListener(this);
        b3=new Button("3");
                            b3.setFont(f);
                            b3.addActionListener(this);
        b4=new Button("4");
                            b4.setFont(f);
                            b4.addActionListener(this);
        b5=new Button("5");
                            b5.setFont(f);
                            b5.addActionListener(this);
        b6=new Button("6");
                            b6.setFont(f);
                            b6.addActionListener(this);
        b7=new Button("7");
                            b7.setFont(f);
                            b7.addActionListener(this);
        b8=new Button("8");
                            b8.setFont(f);
                            b8.addActionListener(this);
        b9=new Button(" ");
                            b9.setFont(f);
                            b9.addActionListener(this);

        add(b1); add(b2); add(b3);
        add(b4); add(b5); add(b6);
        add(b7); add(b8); add(b9);




    } 
    public void actionPerformed(ActionEvent ae)
    {
        if(ae.getSource() == b1)
        {
            if(b2.getLabel() == " ")
            {
                b2.setLabel(b1.getLabel());
                b1.setLabel(" ");
            }
        else if(b4.getLabel() == " ")
            {

              b4.setLabel(b1.getLabel());
                b1.setLabel(" ");
            }

        }
        if(ae.getSource() == b2)
        {
            if(b1.getLabel() == " ")
            {
                b1.setLabel(b2.getLabel());
                b2.setLabel(" ");
            }
        else if(b3.getLabel() == " ")
            {

              b3.setLabel(b2.getLabel());
                b2.setLabel(" ");
            }
            else if(b5.getLabel() == " ")
            {

              b5.setLabel(b2.getLabel());
                b2.setLabel(" ");
            }

        }
        if(ae.getSource() == b3)
        {
            if(b2.getLabel() == " ")
            {
                b2.setLabel(b3.getLabel());
                b3.setLabel(" ");
            }
        else if(b6.getLabel() == " ")
            {

              b6.setLabel(b3.getLabel());
                b3.setLabel(" ");
            }

        }
        if(ae.getSource() == b4)
        {
            if(b1.getLabel() == " ")
            {
                b1.setLabel(b4.getLabel());
                b4.setLabel(" ");
            }
        else if(b5.getLabel() == " ")
            {

              b5.setLabel(b4.getLabel());
                b4.setLabel(" ");
            }
            else if(b7.getLabel() == " ")
            {

              b7.setLabel(b4.getLabel());
                b4.setLabel(" ");
            }

        }
        if(ae.getSource() == b5)
        {
            if(b2.getLabel() == " ")
            {
                b2.setLabel(b5.getLabel());
                b5.setLabel(" ");
            }
        else if(b4.getLabel() == " ")
            {

              b4.setLabel(b5.getLabel());
                b5.setLabel(" ");
            }
            else if(b6.getLabel() == " ")
            {

              b6.setLabel(b5.getLabel());
                b5.setLabel(" ");
            }
            else if(b8.getLabel() == " ")
            {

              b8.setLabel(b5.getLabel());
                b5.setLabel(" ");
            }

        }
        if(ae.getSource() == b6)
        {
            if(b3.getLabel() == " ")
            {
                b3.setLabel(b6.getLabel());
                b6.setLabel(" ");
            }
        else if(b5.getLabel() == " ")
            {

              b5.setLabel(b6.getLabel());
                b6.setLabel(" ");
            }
        else if(b9.getLabel() == " ")
            {

              b9.setLabel(b6.getLabel());
                b6.setLabel(" ");
            }

        }
        if(ae.getSource() == b7)
        {
            if(b4.getLabel() == " ")
            {
                b4.setLabel(b7.getLabel());
                b7.setLabel(" ");
            }
        else if(b8.getLabel() == " ")
            {

              b8.setLabel(b7.getLabel());
                b7.setLabel(" ");
            }

        }
        if(ae.getSource() == b8)
        {
            if(b5.getLabel() == " ")
            {
                b5.setLabel(b8.getLabel());
                b8.setLabel(" ");
            }
        else if(b7.getLabel() == " ")
            {

              b7.setLabel(b8.getLabel());
                b8.setLabel(" ");
            }
            else if(b9.getLabel() == " ")
            {

              b9.setLabel(b8.getLabel());
                b8.setLabel(" ");
            }

        }
        if(ae.getSource() == b9)
        {
            if(b6.getLabel() == " ")
            {
                b6.setLabel(b9.getLabel());
                b9.setLabel(" ");
            }
        else if(b8.getLabel() == " ")
            {

              b8.setLabel(b9.getLabel());
                b9.setLabel(" ");
            }

        }

    }
    public static void main(String args[])
    {

      new Puzzle();
    }
}

Answer 1

你可以这样做：

// global scope
List<Integer> container = new ArrayList<>();

//populate it
for(int i =1; i<=8; i++){
   container.add(i);
}
..........
..........
..........
public static int getRandom(){
    //to refill it if ya need to call it more than 8 times
    //if(container.size()==0){for(int i=1; i<=8; i++){container.add(i);} 
    Random generator = new Random();

    Integer randomNumber = container.get(generator.nextInt(container.size()));

    container.remove(randomNumber);

    return randomNumber;
}

此外，如果你想 name/label 每个按钮随机具有从 1 到 8 的唯一编号，例如：

b1=new Button(String.valueOf(getRandom()));

以此类推

Answer 2

一般回答：

编辑：抱歉，这与其他人发布的内容基本相同。他第一个做到了。

ArrayList<Integer> draw = new ArrayList<Integer>();
for(int i = 1; i<=8; i++){
    draw.add(i); //Add every number once
}

//Every time you call it, you pick a random item from the list.
//Then you remove it from it to prevent being recalled. Therefore it won't be re-accesed.
Random r = new Random();
int placeholder = r.nextInt(draw.size());
int num = draw.get(placeholder);
draw.remove(placeholder);

对你来说，这是你应该做的：

...
ArrayList<Button> buttonlist = new ArrayList<Button>(); /// ADD THIS. Put this outside the method/function.
...
Puzzle(){
    setTitle("Shuffle");
    setSize(500,500);
    setLayout(new GridLayout(3,3));
    setVisible(true);
    Font f=new Font("Arial",Font.BOLD,100);

    b1=new Button("1");
                        b1.setFont(f);
                        b1.addActionListener(this);
                        buttonlist.add(b1); /// ADD THIS
    b2=new Button("2");
                        b2.setFont(f);
                        b2.addActionListener(this);
                        buttonlist.add(b2); /// ADD THIS
    b3=new Button("3");
                        b3.setFont(f);
                        b3.addActionListener(this);
                        buttonlist.add(b3); /// ADD THIS
    b4=new Button("4");
                        b4.setFont(f);
                        b4.addActionListener(this);
                        buttonlist.add(b4); /// ADD THIS
    b5=new Button("5");
                        b5.setFont(f);
                        b5.addActionListener(this);
                        buttonlist.add(b5); /// ADD THIS
    b6=new Button("6");
                        b6.setFont(f);
                        b6.addActionListener(this);
                        buttonlist.add(b6); /// ADD THIS
    b7=new Button("7");
                        b7.setFont(f);
                        b7.addActionListener(this);
                        buttonlist.add(b7); /// ADD THIS
    b8=new Button("8");
                        b8.setFont(f);
                        b8.addActionListener(this);
                        buttonlist.add(b8); /// ADD THIS
    b9=new Button(" ");
                        b9.setFont(f);
                        b9.addActionListener(this);
                        buttonlist.add(b9); /// ADD THIS
    Random r = new Random(); /// ADD THIS
    while(buttonlist.size() != 0){ /// ADD THIS
        int placeholder = r.nextInt(buttonlist.size()); /// ADD THIS
        Button button = buttonlist.get(placeholder); /// ADD THIS
        add(button); /// ADD THIS AFTER REPLACING all the original add(b1)...
        buttonlist.remove(placeholder); /// ADD THIS
    } /// ADD THIS
}

这与建议给它一个单独名称的其他人的反应有点不同，我相信这种方法会更好一些，因为 b1 没有标签 3 或其他东西。这样，洗牌顺序的答案将只是 b1、b2、b3... 而不是随机顺序。这在实际洗牌边框上的按钮时保留了顺序，否则您将难以识别对象。

Answer 3

由于您是从集合中随机选择一个号码，因此不要使用 Random 号码生成器来选择号码，请使用 Random 号码生成器从剩余的可用号码中选择。

 List<Integer> choices = getNewChoices();
 int choice = choices.remove(random.nextInt(choices.size());

选择最终会越来越小，但未选中的元素还在List。

你可以把它包装成一个保护方法selectOne

public class Whatever {

     public void run() {
         ...
         List<Integer> choices = getNewChoices();
         ...
         int choice = selectOne(choices);
     }

     public List<Integer> getNewChoices() {
         return Arrays.toList(new Integer[] { 1, 2, 3, 4, 5, 6, 7, 8});
     }

     public int selectOne(List<Integer> choices) {
         if (choices.length() > 0) {
             return choices.remove(random.nextInt(choices.size());
         }
         throw new RuntimeException("out of choices");
     }
 }

如何生成1到8的随机数而不重复？

How to generate random numbers from 1 to 8 without repeating them?

java

random

shuffle

awt