问题跟踪程序-ArrayList中的对象

Question

Sorry if I'm making some silly mistakes. I'm working on a school assignment and I'm supposed to create a issue tracking program. Each issue must be represented by an object and the objects must be stored in an ArrayList. There must be a menu where the user has the option to create a new issue, mark a created issue as solved, view solved and unsolved issues. The ArrayList I've made doesn't store the objects correctly whenever I enter a new object all the other objects are changed into the one I enter and I'm stuck at this... Any help will be much appreciated! Thanks!

Here's my code (I think the problem begins at "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();
        }
    }                       
}    

}

The issues class:

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

Basically you are trying to reuse same object again and again and hence you see changing field in one object impacts the other as well. What you should be doing is:

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

And similarly you should be asking for issue number which has been solved and should update only that issue (I would have used Map for this where key would be issue number and value would be IssueTracking)

Answer 2

The problem is that you're reusing the issueNum object - when you enter the first entry this is added to the list, when you enter a second one, you edit the existing entry, then add another copy of the same object, and so on.

Creating a new instance will fix this:

    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();
    }