java - 将相同的数字分组到数组列表中(Big Java Ex 7.5)

Question

即使使用本书给出的一些伪代码作为提示(本章是关于数组和数组列表)，我在弄清楚应该如何解决这个问题时遇到了一些麻烦。顺便说一句，这不是作业，我正在自学。

问题

A run is a sequence of adjacent repeated values. Write a program thatgenerates a sequence of 20 random die tosses and that prints the dievalues, marking the runs by including them in parentheses, like this:1 2 (5 5) 3 1 2 4 3 (2 2 2 2) 3 6 (5 5) 6 3 1

书中提示

Set a boolean variable inRun to false.

For each valid index i in the array list If inRun

If values[i] is different from the preceding value Print ) inRun = False Else

If values[i] is the same as the followingvalue Print ( inRun = True Print Values; [i]

我不明白的是这个提示到底有什么帮助。假设我们有多个数字，如 2 2 2 2 这不会只是做类似 (2 2) 2 2

的事情吗？

这是我到目前为止正在尝试的

import java.util.ArrayList;
import java.util.Random;
class seq
{
    private ArrayList<Integer> nums;
    private Random randNum;
    private boolean inRun;
    public seq()
    {
        nums = new ArrayList<Integer>();
        randNum = new Random();
        inRun = false;
    }
    
    public void addToArrList()
    {
        for(int i = 0; i < 20 ; i++)
        {
            int addThisNum = randNum.nextInt(20)+1;
            nums.add(addThisNum);
        }
    }
    
    public void checkSides()
    {
        int count = 0;
        for(int i = 0 ; i < nums.size(); i++)
        {
            if(nums.get(i) != nums.get(i-1))
            {
                inRun = false;
            }
            if(nums.get(i) == nums.get(i+1))
            {
                inRun = true;
            }
        }
    }
    
    public String toString()
    {
        String output = "Array is:";
        if (output.)
    }
}

另一次尝试

import java.util.Random;
import java.util.ArrayList;
class Seq
{
    private ArrayList<Integer> nums;
    private Random randNum;
    public Seq()
    {
        nums = new ArrayList<Integer>();
        randNum = new Random();
    }
    public void fillArrList()
    {
        for (int i = 0 ; i < 20 ; i++)
        {
            int thisRandNum = randNum.nextInt(20)+1;
            nums.add(thisRandNum);
        }
    }
    
    public String toString() {
        StringBuilder result = new StringBuilder();
        boolean inRun = false;
        for (int i = 0; i < nums.size(); i++) {
            if (i < nums.size() - 1 && nums.get(i).equals(nums.get(i + 1))) {
                if (!inRun) {
                    result.append("(");
                }
                result.append(nums.get(i));
                inRun = true;

            } else {
                result.append(nums.get(i));
                if (inRun) {
                    result.append(")");
                }
                inRun = false;

            }
        }
        return result.toString();
    }
}

public class Sequence{
    public static void main(String [] args)
    {
        Seq seqObj = new Seq();
        seqObj.fillArrList();
        System.out.println(seqObj.toString());
    }
}

输出

85641520612614320473181113612

201362181920141020(1919)514920162914

等

Answer 1

我认为他们的意思是这样的:

@Override
public String toString() {
    StringBuilder result = new StringBuilder();
    boolean inRun = false;
    for (int i = 0; i < nums.size(); i++) {
        if (i < nums.size() - 1 && nums.get(i).equals(nums.get(i + 1))) {
            if (!inRun) {
                result.append("(");
            }
            result.append(nums.get(i));
            inRun = true;

        } else {
            result.append(nums.get(i));
            if (inRun) {
                result.append(")");
            }
            inRun = false;

        }
    }
    return result.toString();
}

此外，您可能希望生成 1 到 6 之间的随机数，即

int addThisNum = randNum.nextInt(6) +1;