How to solve - java.lang.IllegalArgumentException: text cannot be null or empty

Question

I am trying to declare variables at the top of the class so I don't have to declare them constantly when using them. I have done so no error comes up until I want to run the program. My code is below:

public class UI extends javax.swing.JFrame {

/**
 * Creates new form UI
 */
public UI() {    
    initComponents();
    this.service.setUsernameAndPassword("9a1d5de6-7c2b-427d-a574-d6fe097c86b9", "ztil6GSHwd34");  
    this.str = txtInput.getText();


}
String str;
PersonalityInsights service = new PersonalityInsights();
 ArrayList<Double> percentagesList = new ArrayList();        
 Profile profile = service.getProfile(str).execute();
 Gson gson = new Gson();  
 Root C = gson.fromJson(profile.toString(), Root.class);
 Root.SubTree t = C.getSubTree(); //Gets subtree from root    
 ArrayList<Children> c = t.getChildren(); //Gets <Children> from Root.getSubTree

Error

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: text cannot be null or empty

I believe it is saying the text str cannot be null or empty. How can I resolve this? the str already has text inside it when running it, so unsure why this error is occurring.

Answer 1

So you have a UI class and all the variable here are data members... Here problem seems to be str which is null and hence ur service is complaining. Data Member are intialised before constructor,hence ur str is null when profile is being set. I would declare the members in class and initialize them in the constructor or give str a valid intial value at line number 6.