Untitled

package foo;

/**
 *
 * @author  mario
 */
public class Foo extends javax.swing.JFrame {
    
    /** Creates new form Foo */
    public Foo() {
        initComponents();
    }
    
            

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        Bar bar = new Bar();
        bar.GetInfos();
        
        
    }                                        
    
    public void WriteToLabel(String mystring) {
        
        jLabel1.setText(mystring);
        
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                Foo foo = new Foo();
                foo.setVisible(true);
            }
        });
    }
    
    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    // End of variables declaration                   
    
}



//=======================================================================


package foo;

/**
 *
 * @author mario
 */
public class Bar {
    
    /** Creates a new instance of Bar */
        
    public void GetInfos() {
    
            //here i would like to call foo.WriteToLabel("string")
            foo.WriteToLabel("123");
    }
    
}