Linking user input to class

Question

Hello there,
I have some code that records a ball around the screen for 30seconds, but i am trying to make this length to the users discretion. I have a seperate class which askes for the user input but I can not link this input to the lengh of scene integeger. I was told to use global variables but I have tried but it gives me 2 errors in my class where I have tried to add the userinput to the time frame;
1. ; expected
2.Cannot resolve symbol variable string
here is the code where I have declared the global variable;
public class Example2 extends JFrame implements ActionListener {
public static String inputValue;
public void actionPerformed(ActionEvent e) {
     if (e.getActionCommand().equals("Timer")) {
String inputValue = JOptionPane.showInputDialog("Length Of Scene");
System.out.println("Length of Scene " + inputValue);
and here's the code where I have tried to link the user input to the lengh of scene;
public class Example extends Panel implements TalktativeGuy, MouseListener
     int timeFrame = String Example2.inputValue;
any suggestions?

Answer 1

Scope is the key.
    public static String inputValue;
    public void actionPerformed(ActionEvent e) {
        if (e.getActionCommand().equals("Timer")) {
            String inputValue = JOptionPane.showInputDialog("Length Of Scene"); The first statement is a member variable in class scope (by definition). It appears not to be instantiated and so has the value null. The last statement is a local variable urelated to the first statement. If you remove the type (String) from the last statement then it becomes the instantiation/assignment for the first statement (which will no longer be null).
About the two errors you listed: the stack trace will tell you what class each is in, the sequence of method calls in the class and usually will also tell you the line number where the trouble lies. You can use this information to track down the errors.