Question

对不起，如果我犯了一些愚蠢的错误。我正在完成一项学校任务，我应该创建一个问题跟踪计划。每个问题必须由对象表示，并且对象必须存储在ArrayList中。必须有一个菜单，用户可以选择创建新问题，将已创建的问题标记为已解决，查看已解决和未解决的问题。每当我输入一个新对象时，我所制作的ArrayList都没有正确存储对象。所有其他对象都被改为我输入的那个对象并且我坚持这个...任何帮助将不胜感激！谢谢！

这是我的代码（我认为问题始于“if（option == 1）”）：

public static void main(String[] args) {
    int option = 0;
    Scanner input = new Scanner(System.in);

    ArrayList<IssueTracking> myIssueList = new ArrayList<>();
    IssueTracking issueNum = new IssueTracking();  

    mainMenu();
    option = input.nextInt();

    while (option != 1 && option != 2 && option != 3 && option != 4 && option != 0){
        System.out.println("Invalid option, please choose 1, 2, 3, 4 or 0 in the menu.");
        mainMenu();
        option = input.nextInt();
     }

    while(option !=0){

        while (option != 1 && option != 2 && option != 3 && option != 4 && option != 0){
        System.out.println("Invalid option, please choose 1, 2, 3, 4 or 0 in the menu.");
        mainMenu();
        option = input.nextInt();
     }


        if (option == 1){
            System.out.println("Please describe the issue bellow: ");
            String issueDescription = input.nextLine();
            issueDescription = input.nextLine();

            issueNum.setIssueDescription(issueDescription);
            issueNum.setIsSolved(Boolean.FALSE );
            myIssueList.add(issueNum);
            System.out.println(myIssueList.toString().replace("[", "").replace("]", "").replace(",", ""));   

            returnMenu();
            mainMenu();
            option = input.nextInt();
        }
        if (option == 2){
            System.out.println("Please press 1 to mark the issue as solved: ");
            Boolean isSolved = input.nextBoolean();

            issueNum.setIsSolved(isSolved);

            myIssueList.add(issueNum);
            //System.out.println("\n"+myIssueList.toString().replace("[", "").replace("]", ""));  

            returnMenu();
            mainMenu();
            option = input.nextInt();
        }    

        if (option == 3){
            //View unsolved issues.
            System.out.println(myIssueList);

            returnMenu();

            mainMenu();
            option = input.nextInt();

        }
        if (option == 4){
            //View solved issues.
            System.out.println(issueNum.getIssueDeString()+issueNum.getIsSolved());

            returnMenu();

            mainMenu();
            option = input.nextInt();
        }
    }                       
}

}

问题类：

public class IssueTracking {
private String issueDescription;
private Boolean issueSolved;

public void setIssueDescription(String issueDescription){
    this.issueDescription = issueDescription;
}

public String getIssueDeString(){
    return issueDescription;
} 

public void setIsSolved (Boolean issueSolved){
    this.issueSolved = issueSolved;
}

public Boolean getIsSolved() {
    return issueSolved;
}

public String toString(){
    return "The issue is: " + getIssueDeString() +"\n"+ "The issue is solved: " + getIsSolved()+"\n"; // 
}

Answer 1

基本上，您正在尝试一次又一次地重复使用同一个对象，因此您会看到一个对象中的更改字段也会影响另一个对象。你应该做的是：

if (option == 1) {
      IssueTracking issueNum = new IssueTracking();
      ...//get or set values
      myIssueList.add(issueNum);
}

同样地，你应该要求已经解决的问题编号，并且应该只更新那个问题（我会使用Map来解决这个问题，其中密钥将是问题编号，值将是IssueTracking）

Answer 2

问题是您正在重复使用issueNum对象 - 当您输入第一个条目时，它会添加到列表中，当您输入第二个条目时，您编辑现有条目，然后添加另一个副本相同的对象，等等。

创建新实例将解决此问题：

    if (option == 1){
        System.out.println("Please describe the issue bellow: ");
        String issueDescription = input.nextLine();
        issueDescription = input.nextLine();

        issueNum=new IssueTracking();
        issueNum.setIssueDescription(issueDescription);
        issueNum.setIsSolved(Boolean.FALSE );
        myIssueList.add(issueNum);
        System.out.println(myIssueList.toString().replace("[", "").replace("]", "").replace(",", ""));   

        returnMenu();
        mainMenu();
        option = input.nextInt();
    }

问题跟踪程序 - ArrayList中的对象

2 个答案: