如何在不同类别的jtextarea上打印文本消息

Question

I created a console based program that allowed users to take a math quiz. The program basically generated random numbers and determined if the answer was right or wrong.

Now, I'm trying to create the GUI version of this program and I'm stuck.

I want to print text messages in the jtextarea from a different class. I've used the get and set methods, but for some reason it doesn't output the text messages. I've done some research on swing workers but I have no idea how to get it to work so I'm trying to avoid using it if possible.

This is not a homework assignment. I started learning java 4 months ago so i may not understand advance concepts.

I guess what I want to know... do I have to use swing workers? all really want to do is generate random numbers and output the result in the jtextarea... it shouldn't freeze the gui, right? Anyway, thanks in advance.

 package algorithmsProgramGUI.view; import java.awt.EventQueue; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.border.EmptyBorder; import java.awt.Toolkit; import java.awt.Panel; import javax.swing.JLabel; import java.awt.Font; import javax.swing.text.JTextComponent; import javax.swing.JFormattedTextField; import java.awt.Choice; import java.awt.Label; import javax.swing.JPopupMenu; import java.awt.Component; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.TextArea; import java.awt.Button; import org.eclipse.wb.swing.FocusTraversalOnArray; import javax.swing.JTextArea; public class ProFrame extends JFrame { /** * */ private static final long serialVersionUID = -7222968352076888482L; private static JTextArea textArea; private JPanel contentPane; public static JTextArea getTextArea() { return textArea; } public static void setTextArea(JTextArea string) { ProFrame.textArea = string; } /** * Launch the application. */ public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { ProFrame frame = new ProFrame(); frame.setVisible(true); } catch (Exception e) { e.printStackTrace(); } } }); } /** * Create the frame. */ public ProFrame() { setIconImage(Toolkit.getDefaultToolkit().getImage(ProFrame.class.getResource("/algorithmsProgramGUI/resources/AlgorithmsLogo.png"))); setTitle("Algorithms"); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setBounds(100, 100, 864, 590); contentPane = new JPanel(); contentPane.setToolTipText("Choose a test to take"); contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); setContentPane(contentPane); contentPane.setLayout(null); JLabel lblSelectTest = new JLabel("Select Test :"); lblSelectTest.setFont(new Font("Times New Roman", Font.BOLD, 15)); lblSelectTest.setBounds(35, 42, 95, 14); contentPane.add(lblSelectTest); JFormattedTextField formattedTextField = new JFormattedTextField(); formattedTextField.setToolTipText("Input answer here"); formattedTextField.setBounds(419, 415, 108, 24); contentPane.add(formattedTextField); Label label = new Label("Answer :"); label.setFont(new Font("Times New Roman", Font.BOLD, 15)); label.setBounds(339, 415, 74, 22); contentPane.add(label); Panel status_panel = new Panel(); status_panel.setFont(new Font("Times New Roman", Font.PLAIN, 12)); status_panel.setBounds(220, 445, 558, 75); contentPane.add(status_panel); Button button_1 = new Button("Next Question"); button_1.setFont(new Font("Times New Roman", Font.BOLD, 15)); button_1.setBounds(545, 415, 154, 22); contentPane.add(button_1); JTextArea textArea = new JTextArea(); textArea.setEditable(false); textArea.setBounds(257, 62, 521, 305); contentPane.add(textArea); Choice Test = new Choice(); Test.setFont(new Font("Times New Roman", Font.BOLD, 12)); Test.setBounds(35, 62, 130, 20); Test.add("Practice Quiz"); Test.add("Test 1"); Test.add("Test 2"); contentPane.add(Test); Button button = new Button("Generate Test"); button.setFont(new Font("Times New Roman", Font.BOLD, 15)); button.setBounds(35, 235, 117, 26); button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { String s = Test.getSelectedItem().toString(); textArea.setText(s); textArea.setFont(new Font("Times New Roman", Font.BOLD, 12)); if (Test.getSelectedItem().equalsIgnoreCase("Practice Quiz")) { algorithmsProgramGUI.view.PracticeQuizGUI.runPracticeQuizGUI(); } if (Test.getSelectedItem().equalsIgnoreCase("Test 1")) { textArea.setText("Test 1 is not available at this time."); } if (Test.getSelectedItem().equalsIgnoreCase("Test 2")) { textArea.setText("Test 2 is not available at this time."); } } }); contentPane.add(button); contentPane.setFocusTraversalPolicy(new FocusTraversalOnArray(new Component[]{label, formattedTextField, Test, button, status_panel, lblSelectTest, button_1})); } @SuppressWarnings("unused") private static void addPopup(Component component, final JPopupMenu popup) { component.addMouseListener(new MouseAdapter() { public void mousePressed(MouseEvent e) { if (e.isPopupTrigger()) { showMenu(e); } } public void mouseReleased(MouseEvent e) { if (e.isPopupTrigger()) { showMenu(e); } } private void showMenu(MouseEvent e) { popup.show(e.getComponent(), e.getX(), e.getY()); } }); } public static void setTextArea(String string) { // TODO Auto-generated method stub } } 

 package algorithmsProgramGUI.view; import javax.swing.JTextArea; import javax.swing.text.JTextComponent; import java.awt.*; public class PracticeQuizGUI { static void runPracticeQuizGUI() { // System.out.println("This statement was created in PracticeQuizGUI class."); //algorithmsProgramGUI.view.ProFrame.ProFrame().textArea.setText("s"); //algorithmsProgramGUI.view.ProFrame.getTextArea(); algorithmsProgramGUI.view.ProFrame.setTextArea("Welcome to the practice quiz."); //algorithmsProgramGUI.view.ProFrame.getTextArea(); } } 

Answer 1

in your current code:

public static void setTextArea(String string) {
    // TODO Auto-generated method stub
}

nothing is being done, use JTextArea.setText(String t) method to set the value