JPanel hurts my brain

[Tallguy]

Greetings All!!!

I am once again back into java Here is my dilemma i am using the GUI's in JPanel (ONLY) to create a GUI for a calculator. I just can not for the life of me get it to appear on my screen, the array holds the String values to be used in GridLayout. i am only able to BorderLayout || FlowLayout || GridLayout. I can do this in about 10 min using JFrame, but we are not allowed to touch it.

Here is the code that matters

Any help would be awesome

code:

import java.awt.*; import javax.swing.*; public class CalculatorView extends JPanel {         private static final long serialVersionUID = 1L;         public CalculatorView() {         }                 public  void addButton() {                                 JPanel content = new JPanel(new BorderLayout());                                  int width =  256;                     int height = 256;                     Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();                     int x = (screen.width-width)/2;                     int y = (screen.height-height)/2;                     setBounds(x,y,width,height);                 JPanel buttons = new JPanel();                 buttons.setLayout(new GridLayout(4,5,5,10));                             content.setBorder(BorderFactory.createEmptyBorder (0,2,5,2));                 String [] values = { "7", "8", "9","/", "P","4","5","6","*","\u221A","1","2","3","-","C","0",".","+/-","+","="};         for (int i=0; i<values.length ; i++){                 buttons.add(new Button(values[i]));                 System.out.print (values[i]);                 }         content.add(buttons,BorderLayout.SOUTH);         content.setVisible(true);                         } }

MY MAIN

code:

import java.awt.EventQueue; public class Calculator {         public static void main(String[] args) {             EventQueue.invokeLater(new Runnable() {                         public void run (){                                 System.out.print ("3\n");                             CalculatorView calcview = new CalculatorView ();                             calcview.addButton();                             calcview.setVisible(true);                         }                   });                 } }

[Insectoid]

I've never been able to get any of Java's gui elements to do what I want. If you were me you'd give up now, but you're Tallguy, not me, so don't give up.

Then again, I am six & a half feet tall, so maybe you are me.

[Tony]

Doesn't answer your question, but... are you using Java 5+ ? for-each loops are your friend

Tallguy @ Thu Oct 04, 2012 5:02 pm wrote:

String [] values = { "7", "8", "9","/", "P","4","5","6","*","\u221A","1","2","3","-","C","0",".","+/-","+","="};

for (int i=0; i<values.length ; i++){
buttons.add(new Button(values[i]));
System.out.print (values[i]);
}

vs.

code:

String [] values = {...} // same for (String value : values ) {    buttons.add(new Button(value)); }

[DemonWasp]

JPanels represent "panel" components, not "frame" components: that is, they don't represent windows on their own. You need to add them to a JFrame (or other container) which is being drawn to have the panel be drawn. See: http://docs.oracle.com/javase/tutorial/uiswing/components/toplevel.html

I don't understand how you're supposed to complete this assignment "without touching JFrame".

Edit: You could use another top-level container, such as JDialog or JApplet.

[TokenHerbz]

yeah JApplet would, but i find with that the complier (i suppose depending which you use) wont detect bugs that are found compiling to JFrame.. so i would use JFrame and then change it to JApplet.

[DemonWasp]

I'm not sure what you mean by that sentence. If your compiler isn't finding compile-time problems, then it's not compliant with the Java Language Specification, which means it is not a Java compiler. Which compiler were you having trouble with (and give an example of the code in question)?

[Tallguy]

Thank you all - I have got it to work. Note that this assignment is just the GUI aspect, once i get the application working I'll post in submissions. Here is the fix, my main was able to use JFrame, just none of the contents

Main

Java:

/*  * File name: Calculator.java  * Author: Tallguy  * Professor:-----  * Purpose: The driver class for my Swing GUI, responsible for running everythings. Calls the splash screen  *                and creates an intial frame(JFrame) in which to hold the contents (buttons, text field etc)  *                of all aspects of the calculator to be created.  * Class list: []  */ import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Toolkit; import javax.swing.JFrame; /************************************************ @author Tallguy @version 1 @see [javax.swing.*, java.awt*] @since java 1.6  ************************************************/ public class Calculator {         public static void main(String[] args) {                 /************************************************                 {@value} WIDTH - constant var for the screen width                 {@value} HEIGHT - constant var for the screen height                 ************************************************/                 final int WIDTH = 256;                 final int HEIGHT = 256;                 EventQueue.invokeLater(new Runnable() {                         /************************************************                         Creates the initial JFrame settings its values, such as height/width and resizable                         factors. It thens adds contents to the frame                         @param []                         @return [ ]                          ************************************************/                         public void run() {                                 CalculatorView calcview = new CalculatorView();                                 JFrame frame = new JFrame("Calculator");/*creates a new JFrame object*/                                 frame.setResizable(false);                                 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);/*overrides default close oepration (close window) to kill process*/                                 int width = WIDTH;                                 int height = HEIGHT;                                 Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();                                 int x = (screen.width - width) / 2;                                 int y = (screen.height - height) / 2;                                 frame.setBounds(x, y, width, height);/*sets screen size*/                                 frame.add(calcview);/*adds contents to the JFrame*/                                                     frame.setVisible(true);/*makes the screen visible*/                         }                 });         } }

CalculatorView

Java:

/*  * File name: CalculatorView.java  * Author: Tallguy  */ import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.*; import javax.swing.border.Border; public class CalculatorView extends JPanel {         private static final long serialVersionUID = 1L;         private JTextField display;         private JLabel error;         private JButton dotButton, backspace, btn;         private JPanel viewPanel;         private JRadioButton radioInt, radioFl;         private ButtonGroup Rbgroup/* = new ButtonGroup()*/;         public CalculatorView() {                 this.setLayout(new BorderLayout());                 this.setBorder(BorderFactory.createEmptyBorder(0, 2, 5, 2));                 Controller handler = new Controller();                 /* sets look and feel to work on both Win and MacOS */                 try {                         UIManager.setLookAndFeel(UIManager                                         .getCrossPlatformLookAndFeelClassName());                 } catch (Exception e) {                         e.printStackTrace();                 }                 /* sets look and feel to work on both Win and MacOS - END */                 /* radio buttons */                 JPanel Rbutton = new JPanel(new FlowLayout());                 Border outer = BorderFactory.createEmptyBorder(0, 15, 3, 15);                 Border inner = BorderFactory.createLineBorder(Color.BLUE, 4);                 Rbutton.setBorder(BorderFactory.createCompoundBorder(outer, inner));                 Rbgroup = new ButtonGroup();;                 Rbutton.setFocusable(false);                 /* radio buttons - END */                 /* north layer parts */                 /* backspace button */                 backspace = new JButton("<<");                 backspace.setPreferredSize(new Dimension(20, 20));                 backspace.setBorder(BorderFactory.createEmptyBorder());                 backspace.setOpaque(false);                 backspace.setToolTipText("Backspace (Alt-B)");                 backspace.setContentAreaFilled(false);                 backspace.setBorderPainted(false);                 backspace.setMnemonic('B');                 backspace.setFocusPainted(false);                 backspace.addActionListener(handler);                 /* backspace button - END */                 /* text field */                 display = new JTextField("0.0", 15);                 display.setHorizontalAlignment(JTextField.RIGHT);                 display.setBackground(Color.WHITE);                 display.setEditable(false);                 /* text field - END */                 /* error field */                 error = new JLabel(" ");                 error.setPreferredSize(new Dimension(20, 20));                 error.setBorder(BorderFactory.createEmptyBorder());                 error.setOpaque(true);                 error.setBackground(Color.GREEN);                 error.setToolTipText("Error");                 /* error field - END */                 /* north layer parts - END */                 /* holds all north end parts */                 viewPanel = new JPanel(new FlowLayout());                 viewPanel.add(error, BorderLayout.WEST);                 viewPanel.add(display, BorderLayout.NORTH);                 viewPanel.add(backspace, BorderLayout.EAST);                 /* holds all north end parts - END */                 /* calc buttons */                 JPanel buttons = new JPanel(new GridLayout(4, 5, 5, 5));                 String[] values = { "7", "8", "9", "/", "P", "4", "5", "6", "*",                                 "\u221A", "1", "2", "3", "-", "C", "0", ".", "+/-", "+", "=" };                 for (String value : values) {                         addButton(buttons, value, handler);                 }                                 String[] radio = { "Integer", "Float" };                 for (String value : radio) {                         addButton(Rbutton, value, handler);                                }                 /* calc buttons - END */                                 /* adds all to master panel */                 this.add(viewPanel, BorderLayout.NORTH);                 this.add(Rbutton, BorderLayout.CENTER);                 this.add(buttons, BorderLayout.SOUTH);                 /* adds all to master panel - END */         }         private void addButton(Container c, String s, ActionListener handler) {                 if (s == "Integer") {                         radioInt = new JRadioButton("Integer", false);                         radioInt.setFont(new Font("Serif", Font.BOLD, 12));                         radioInt.setBackground(Color.yellow);                         radioInt.addActionListener(handler);                         radioInt.setFocusPainted(false);                         Rbgroup.add(radioInt);                         c.add(radioInt);                 } else if (s == "Float") {                         radioFl = new JRadioButton("Float", true);                         radioFl.setFont(new Font("Serif", Font.BOLD, 12));                         radioFl.setBackground(Color.PINK);                         radioFl.addActionListener(handler);                         radioFl.setFocusPainted(false);                         Rbgroup.add(radioFl);                         c.add(radioFl);                 } else {                         btn = new JButton(s);                         btn.setPreferredSize(new Dimension(30, 33));                         btn.setForeground(Color.BLUE);                         btn.setFont(new Font("Serif", Font.BOLD, 12));                         if (s == "+/-") {                                 btn.setFont(new Font("Serif", Font.BOLD, 10));                         }                         if (s == ".") {                                 dotButton = btn;                         }                         if (s == "C") {                                 btn.setBackground(Color.RED);                                 btn.setForeground(Color.black);                         }                         if (s == "=") {                                 btn.setBackground(Color.yellow);                                 btn.setForeground(Color.black);                         }                         btn.setFocusPainted(false);                         btn.addActionListener(handler);                         c.add(btn);                 }         }         private class Controller implements ActionListener {                 public void actionPerformed(ActionEvent e) {                         String digit = e.getActionCommand();                                        display.setText(digit);                                 //display.setText(display.getText() + digit);                          }         } }

@Tony - You are awesome good sir, I always forget about the for-each loops

Tony wrote:

Doesn't answer your question, but... are you using Java 5+ ? for-each loops are your friend

Insectoid wrote:

I've never been able to get any of Java's gui elements to do what I want. If you were me you'd give up now, but you're Tallguy, not me, so don't give up.

Then again, I am six & a half feet tall, so maybe you are me.

-only 6'4"


EDIT-Added syntax

[QuantumPhysics]

Its not JPanel, its just java overall. Why not use a Applet or Jython wx package.

[Tallguy]

assignment specifications

[QuantumPhysics]

Oh. Fair Enough.