Java errors for a simple program compilation process, please help

Question

I am new here, but I have been dealing with this unknown problem for a long time. Please browse through this simple program that I encoded and explained why it will not compile for me. The fact is that I copied this code from the teacher, and it works fine on his machine. Then, when I tried to run the example on my machine, I get 13 errors!

Here is the first class:

import java.awt.*; import java.awt.event.*; import javax.swing.*; class radio extends JFrame{ private JTextField tf; private Font pf; private Font bf; private Font itf; private Font bif; private JRadioButton pb; private JRadioButton bb; private JRadioButton ib; private JRadioButton bib; private ButtonGroup group; public radio(){ super("raido buttonseses"); setLayout(new FlowLayout()); tf = new JTextField("buggedy buggedy boo", 25); add(tf); pb = new JRadioButton("plain", true); bb = new JRadioButton("bold", false); ib = new JRadioButton("italic", false); bib = new JRadioButton("bold and italic", false); add(pb); add(bb); add(ib); add(bib); group = new ButtonGroup(); group.add(pb); group.add(bb); group.add(ib); group.add(bib); pf = new Font("Serif", Font.PLAIN, 14); bf = new Font("Serif", Font.BOLD, 14); itf = new Font("Serif", Font.ITALIC, 14); bif = new Font("Serif", Font.BOLD + Font.ITALIC, 14); tf.setFont(pf); //wait for event to happen pass in font obj to constructor pb.addItemListener(new HandlerClass(pf)); bb.addItemListener(new HandlerClass(bf)); ib.addItemListener(new HandlerClass(itf)); bib.addItemListener(new HandlerClass(bif)); } private class HandlerClass implements ItemListener{ private Font font; // font obj gets variable font public HandlerClass(Font f){ font = f; } //sets font to font obj that was passed in public void itemStateChanged(ItemEvent event){ tf.setFont(font); } } } 

Then here is the second main class that I tried to run:

 import javax.swing.JFrame; public class radiobutton{ public static void main(String[] args) { radio go = new radio(); go.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); go.setSize(300,200); go.setVisible(true); } } 

I know that someone looks at this and thinks that the answer is so obvious, but a novice like me is not very clear. Here are the errors that I returned to me when I try to compile:

 javac radiobutton.java ./JFrame.java:1: JFrame is already defined in this compilation unit import javax.swing.JFrame; ^ radiobutton.java:7: cannot find symbol symbol : method setDefaultCloseOperation(int) location: class radio go.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); ^ radiobutton.java:8: cannot find symbol symbol : method setSize(int,int) location: class radio go.setSize(300,200); ^ radiobutton.java:9: cannot find symbol symbol : method setVisible(boolean) location: class radio go.setVisible(true); ^ ./JFrame.java:8: cannot find symbol symbol : variable EXIT_ON_CLOSE location: class JFrame go.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); ^ ./radio.java:19: cannot find symbol symbol : constructor JFrame(java.lang.String) location: class JFrame super("raido buttonseses"); ^ ./radio.java:20: cannot find symbol symbol : method setLayout(java.awt.FlowLayout) location: class radio setLayout(new FlowLayout()); ^ ./radio.java:22: cannot find symbol symbol : class JTExtField location: class radio tf = new JTExtField("buggedy buggedy boo", 25); ^ ./radio.java:23: cannot find symbol symbol : method add(javax.swing.JTextField) location: class radio add(tf); ^ ./radio.java:30: cannot find symbol symbol : method add(javax.swing.JRadioButton) location: class radio add(pb); ^ ./radio.java:31: cannot find symbol symbol : method add(javax.swing.JRadioButton) location: class radio add(bb); ^ ./radio.java:32: cannot find symbol symbol : method add(javax.swing.JRadioButton) location: class radio add(ib); ^ ./radio.java:33: cannot find symbol symbol : method add(javax.swing.JRadioButton) location: class radio add(bib); ^ 13 errors 

I assume this has something to do with the asterisk when importing java functions. Am I here on the right track? Thanks for looking at this stupid issue and any help is much appreciated.

Answer 1

It compiles fine for me.

This is probably a mistake: You have another file named JFrame.java in the source folder. Delete this file! JFrame is already defined in the API.

Error message ...

 ./JFrame.java:1: JFrame is already defined in this compilation unit import javax.swing.JFrame; 

... shows that ./JFrame.java exists in the same package as radiobutton .

(As a note, I want to mention that, in accordance with Java coding conventions, you should always capitalize class names.)

Answer 2

This is a shot in the dark since I haven’t touched Java for a while, but you compile radio.java and then compile radobutton.java?

Answer 3

 ./JFrame.java:8: cannot find symbol symbol : variable EXIT_ON_CLOSE location: class JFrame go.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

This error message refers to a different source file (JFrame.java). Like aioobe, I am sure that you have a file called JFrame.java in the same directory (package).

To check, try this code:

 // no import statement here! public class radiobutton{ public static void main(String[] args) { radio go = new radio(); go.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE); // ^ changed ^ go.setSize(300,200); go.setVisible(true); } }