Unable to setText for JLabel from another class.

Question

hello,

I am trying to change a JLabels text when a method it executed here's the code I have

declaring the JLabel in the main class -

JLabel textlab = new JLabel();
textlab.setBounds(33, 145, 189, 141);
frmLauncher.getContentPane().add(textlab);

}
public void setLabelText (String text){
//textlab = new JLabel();
textlab.setText(text);

}
// Variables declaration - do not modify
public javax.swing.JLabel textlab;
// End of variables declaration

and here is the code in the updater class that I want to run that will change the text inside the JLabel -

static loop p = new loop(); <------------- here
static String version = "0.0";
static boolean needDownload = false;
public static void start(){
Main();
}
public static void needDownload(){
{
File f = new File(System.getProperty("user.home") + "/ver.txt");
try {
List<String> lines = Files.readAllLines(Paths.get(f.getAbsolutePath()), StandardCharsets.UTF_8);
for (String str : lines){
version = str;
System.out.println("Version: " + str);
p.setLabelText("Version: " + str); <------------ here
}
} catch (IOException e) {
e.printStackTrace();
}
}

when I run the code I get "java.lang.NullPointerException" I understand what this error is as it's very common however I am unable to figure out what the cause of it this time is?

any ideas thanks :3

Answer 1

Supposing than loop is the class containing a reference to target label, are you sure than when you create it you assign it to class field textlab? It seem than you have 2 textlab label which only local one is assigned...