arraylist在单独的循环方法中没有正确打印出来？ 包装类或循环责备？

Question

for my project, i have an arraylist for the user to input whatever names they want in one method as long as it isn't stop. then in a separate method, the values i just inputted have to be called out again, so i can input more information for each name.

example:

1. enter names:
2. name: bob
3. name: joe

4. name: Stop this triggers another method to prompt more info:

5. bob: enter age: enter address:

6. joe: enter age: enter address:

   However, right now, the arraylist isn't printing out correctly, and i'm getting repeats of certain names, while other names don't show up in the second method. Also, the loop in the second method doesn't end. i enter in info for the names i entered, but i keep getting prompted with "name:" and no actual arraylist value. I suspect something is wrong with my loops, but i don't quite know how to fix it? I also thought that maybe the problem has something to do with how i'm using a wrapper to put in values into the arraylist, but i don'tknow how to fix that.

in the second method, I've tried swapping the countervariable to keep track of the order in the Array List with a separate counter in the second method, but it doesn't seem to make a difference. In the first method, i've tried swapping the loop with different a boolean while loop, with a straight up while (!input.equals("Stop")), a for loop counter inside of the previous two options, if loops, and some combination of the above.

here is my code

Scanner console = new Scanner(System.in); private ArrayList<Directory> nameList; //i have to use object oriented programming to store values in the Directory Class public int i;

first method:

private void addName() 
{
    Scanner LocalInput = new Scanner(System.in);
    Directory buffer = null;
    String ID = null;

    System.out.println("Enter Station Designations Below, Enter Stop to quit");
    boolean breaker = false;
    while(breaker ==false)
    {
        System.out.print("Name:  ");
        ID = (LocalInput.nextLine());
        if(ID.equals("Stop"))
            breaker = true;
        else
            buffer = new Directory(ID); 
            nameList.add(buffer); 
    }
}

second method:

private void getInfo()
{
    Scanner LocalInput = new Scanner(System.in);

    Directory buffer;
    buffer = nameList.get(i); 
    double age; String address;


    System.out.println("Enter Temperatures below...");
    System.out.println("" + nameList.get(i));

    for (i = 0; i < nameList.size(); i++) 
    {

        System.out.println("Name: " + buffer.GetID()); //there's a getter and setter in the Directory class
        System.out.println( "Age:\t");
        age = LocalInput.nextDouble();
        System.out.print( "Address:\t");   
        address = LocalInput.nextLine();
        buffer= new Directory(age, address);
        nameList.add(buffer);
    }
}

Answer 1

Critique of first method

I haven't looked closely yet, but I strongly suspect this is the problem:

if(ID.equals("Stop"))
    breaker = true;
else
    buffer = new Directory(ID); 
    nameList.add(buffer); 

You appear to be expecting the last statement only to be executing when ID is not equal to "Stop", but actually it's always going to execute. Unlike (say) Python, whitespace is irrelevant in Java. If you statements to be considered as a block, you need braces:

if(ID.equals("Stop"))
    breaker = true;
else {
    buffer = new Directory(ID); 
    nameList.add(buffer); 
}

Personally I would put braces around both parts:

if (ID.equals("Stop")) {
    breaker = true;
} else {
    buffer = new Directory(ID); 
    nameList.add(buffer); 
}

... and quite possibly get rid of the somewhat-irrelevant buffer variable:

if (ID.equals("Stop")) {
    breaker = true;
} else {
    nameList.add(new Directory(ID));
}

I'd also get rid of the breaker variable, and limit the scope of ID (changing its name, too, to comply with normal conventions) with a result of:

while (true) {
    System.out.print("Name:  ");
    string id = LocalInput.nextLine();
    if (id.equals("Stop")) {
        break;
    }
    nameList.add(new Directory(ID));
}

Critique of second method

This is really odd at the moment. It's not at all clear where the i variable is declared, or why you only fetch buffer once, or why you're just adding to the existing list rather than mutating the existing object. I suspect you really want:

for (Directory entry : nameList) {
    System.out.println("Name: " + entry.GetID());
    System.out.println( "Age:\t");
    double age = LocalInput.nextDouble();
    entry.setAge(age);
    System.out.print( "Address:\t");   
    String address = LocalInput.nextLine();
    entry.setAddress(address);
}

Note that your current loop will always continue until i equals nameList.size() - but you're always increasing the size in the loop, so you'll never terminate.

Answer 2

private void getInfo()
{
    Scanner LocalInput = new Scanner(System.in);
    double age; String address;

    for (Directory name : nameList) {
    System.out.println("Name: " + name .GetID());
    System.out.println( "Age:\t");
    double age = LocalInput.nextDouble();
    name.setAge(age);
    System.out.print( "Address:\t");   
    String address = LocalInput.nextLine();
    name.setAddress(address);
}
}

get method should be like this

and Add must be -

private void addName() 
{
    Scanner LocalInput = new Scanner(System.in);
    Directory buffer = null;
    String ID = null;

    System.out.println("Enter Station Designations Below, Enter Stop to quit");
    boolean breaker = false;
    while(breaker ==false)
    {
        System.out.print("Name:  ");
        ID = (LocalInput.nextLine());
        if(ID.equals("Stop"))
            breaker = true;
        else {
            buffer = new Directory(ID); 
            nameList.add(buffer); 
        }
    }
}

Answer 3

Consider using the break keyword, then you don't need the breaker flag and the else branch:

while(true)
{
    System.out.print("Name:  ");
    ID = (LocalInput.nextLine());
    if(ID.equals("Stop"))
        break;

    buffer = new Directory(ID); 
    nameList.add(buffer); 
}

Sorry was already posted...