for循环与嵌套if循环在Java中

Question

Very new to Java, I am in an intro class in college and doing a project. I am trying to make a method that searches a String array for an inputted state and returns the index. If the user enters a query that is not in the array, I would like it to ask for a new state to search. My exception is saying "variable statePosition may not have been initialized." Below is the code.

Thank you in advance!

static final int NUM_STATES = 50;

public static int askState(String[] stateNames) {
    Scanner keyboard = new Scanner(System.in);
    String state;
    int statePosition;
    System.out.println("Please enter a state that you would like to search:");
    state = keyboard.next();
    {
        for (int i = 0; i < NUM_STATES; i++) {
            if (state.equals(stateNames[i])) {
                statePosition = i;
            } else {
                System.out.println("Please enter a valid state:");
            }
            state = keyboard.next();
        }
        return statePosition;
    }

Answer 1

Can you use

 int statePosition = -1;

That would return -1 if it's not found. The error means you didn't assign a value to statePosition.

Answer 2

I think you need to initialize your variable int statePosition; like this:

int statePosition =-1;

Also initialize your String state; like this:

String state = null;

Answer 3

Like the exception states, you have to initialize the int statePosition:

int statePosition = null;

or

int statePosition = 0;

... you know what I mean?

Answer 4

you need to initialize both variables

String state= null;
int statePosition=-1;

Answer 5

The problem here is that you never instantiate the statePosition variable but you are always returning it.

Try give statePosition a value (like others said -1).

Also try to do this with a while (instead of a for statement) which breaks if your statePosition was found.

Answer 6

Your program is prone to encounter an error in one of it variables prior to their use further in the code. I would suggest that every time you code, you should put the variables to initial state rather than leaving them with a null value.

String state= null;
int statePosition=-1;

Put this in the code to have your problems solved.

Answer 7

You might want to change from using int to Integer . Integer is an object so it can be null. This way you can check to see if it has been set before performing any further actions.

static final int NUM_STATES = 50;

public static Integer askState(String[] stateNames) {
    Scanner keyboard = new Scanner(System.in);
    String state;
    Integer statePosition;
    System.out.println("Please enter a state that you would like to search:");
    state = keyboard.next();

    for (int i = 0; i < NUM_STATES; i++) {
        if (state.equals(stateNames[i])) {
            statePosition = i;
        } else {
            System.out.println("Please enter a valid state:");
        }
        state = keyboard.next();
    }
    if (statePosition == null) {
        throw new Exception("State Position Not Set :(");
    }
    return statePosition;
}