Swing和标签setText不起作用

Question

I need a little help with swing. This is my code:

public class UIdostawca extends javax.swing.JFrame {


    /** Creates new form UIdostawca */
    public UIdostawca() {
        initComponents();
        setDefaultCloseOperation(javax.swing.JFrame.HIDE_ON_CLOSE);
    }

    /* This is my function */
    public void loadStuff() {
        jLabel2.setText("Works or not?"); 
    }


    /*
      A lot of code generated by NETBEANS
     */


    // Variables declaration - do not modify
    private javax.swing.JLabel jLabel2;

}

I use it like this:

UIdostawca a = new UIdostawca();

a.loadStuff();

and the jLabel2 didn't change ;(

However when in execute

jLabel2.setText("Works or not?"); 

in function like formWindowOpened

everything works

Answer 1

It's a multi-threading issue. When formWindowOpened is called, it's called by the Swing event dispatch thread (EDT), which is the same thread that draws the interface, so it has the right value of text to draw.

If you call setText from some other thread, the EDT will probably not get the right value for the text. Wherever you call setText in some other thread, you have to wrap it in a SwingUtilities.invokeLater() , which whill change the text value on the EDT.

Answer 2

在第一种情况下，您是否初始化了jLabel2？