在我的特定情况下，如何将此数组转换为列表？

Question

我已经遍历了一个数组 B。检查 arrayList A 中是否存在公共元素。然后删除那些元素并打印出 A 作为数组。

但我的问题是如何打印出 A（在我的程序中它是 System.out.println(crIss.get(m));）作为 arrayList（只是一个没有 [] 的元素列表括号）而不是数组？

这是我正在处理的完整代码：

package issuetracking;

import java.util.*;

public class IssueTrackingObject {

    ArrayList<String> crIss = new ArrayList<String>();

    Scanner input = new Scanner(System.in);
    boolean crIss_bool;
    int numOfSolvedIss;
    private String[] solvedIss;

    //lets user create some issues and add them into an arrayList
    public void createIssue() {
        System.out.println("Enter 5 issues: ");

        for (int i = 0; i < 5; i++) {
            System.out.println("Issue " + (i + 1 + ": "));
            crIss_bool = crIss.add(input.nextLine());
        }

    }
//Let user mark some issues as solved (which are already in the list that the user has just created)

    public void solvedIssue() {
        System.out.println("How many solved issue you have(Must be less than 5): ");
        numOfSolvedIss = input.nextInt();

        solvedIss = new String[numOfSolvedIss];

        for (int k = 0; k < numOfSolvedIss; k++) {
            System.out.print("Enter solved issue(REMEMBER THAT THE SOLVED ISSUE MUST BE FROM ONE OF THEM YOU ALREADY HAVE CREATED)no. " + (k + 1) + ": ");

            solvedIss[k] = input.next();
        }

    }

    public void printUnsolvedIssue() {

for(int m=0; m<solvedIss.length;m++){
      crIss_bool = crIss.remove(solvedIss);

    System.out.println(crIss.get(m));   
}


    }


    public void printSolvedIssue() {
        System.out.println("");
        System.out.println("LIST OF SOLVED ISSUE:");

        for (int l = 0; l < solvedIss.length; l++) {
            System.out.printf("%s ", solvedIss[l]);
        }

    }

}

主要class:

package issuetracking;

import java.util.*;

public class IssueTracking {

    static Scanner input = new Scanner(System.in);

    public static void main(String[] args) {
        IssueTrackingObject its = new IssueTrackingObject();

        System.out.println("                            WELCOME TO ISSUE TRACKING SYSTEM!\n\n");
        System.out.println("Choose from menu: ");
        System.out.println("1. Create new issue\n2. Mark issue(s) as solved\n"
                + "3. View solved issue(s)\n4. View unsolved issue(s)");
        System.out.println("Enter you choise:");
        //String userChoise = input.next();
        //switch-case

        while (true) {
            String userChoise = input.next();

            switch (userChoise) {
                case "1":
                    //System.out.println("Enter 5 issues: ");
                    //call appropriate issue
                    its.createIssue();
                    break;
                case "2":
                    //System.out.println("Mark solved issues (You must enter at least one issue): ");
                    //call appropriate issue
                    its.solvedIssue();
                    break;
                case "3":
                    System.out.println("Solved issue: ");
                    //call appropriate method
                    its.printSolvedIssue();
                    break;

                case "4":
                    System.out.println("Usolved issue: ");
                    //call appropriate issue
                    its.printUnsolvedIssue();
                    break;
                default:
                    System.out.println("Invalid input");
                    break;

            }

        }

    }

}

Answer 1

只需遍历 crIss 并打印其中的每个项目，后跟所需的分隔符。在此示例中，我将使用“,”分隔项目。

public void printUnsolvedIssue() {

   for(int m=0; m<solvedIss.length;m++){
       crIss.remove(solvedIss[i]);
   }

   for(int i = 0; i < crIss.size(); i++) {
       System.out.print(crIss.get(i));
       // only print the delimiter if it isn't the last item in the list
       if(i < crIss.size() - 1) {
           System.out.print(", ");
       }
   }
}

另请注意，我将 crIss.remove(solvedIss) 部分更改为 crIss.remove(solvedIss[i])。这样它将删除 solvedIss.

中的每个项目

Answer 2

您正在体验的打印行为是因为当您打印一个像 ArrayList 的对象时，Java 调用了 Class 的 .toString() 方法。 ArrayList.toString() 继承自 AbstractCollection.toString() 可以找到文档 here。

我建议更改此行为是创建一个类似于以下内容的单独打印函数：

public void printList(ArrayList<String> list)
{
     for(String str : list)
     {
          System.out.print(str+" ");
     }
     System.out.println();
}

然后调用这个函数来代替你的打印语句：

printList(crIss);

请注意，此打印会将列表中的每个元素打印在一行上，并以 space 分隔。

Answer 3

有几种方法可以做到这一点。我给你看三个：

将数据存储在String中并删除不需要的字符：

String tmp = crIss.toString();
tmp = tmp.substring(1, tmp.length() - 1);
System.out.println(tmp);

与上述方法类似，但使用 replace:

String tmp = crIss.toString().replace('[', '[=11=]').replace(']', '[=11=]');
System.out.println(tmp);

遍历 List 并将值存储在 StringBuilder:

StringBuilder sb = new StringBuilder();
for (String string : crIss) {
    sb.append(string).append(", ");
}
sb.remove(sb.length() - 2, sb.length());
System.out.println(sb.toString());

在我的特定情况下，如何将此数组转换为列表？

How do I convert this array into list in my specific case?

java

arrays

loops

for-loop

arraylist