Tochka Zapetaq

Here's my final code. Time to go to bad :-) If you have any comments please post.

import java.applet.*; import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Alpha extends JApplet implements ActionListener { private JLabel inputLabel; private JButton doIt; private JTextField numVariable; private String numAsString; private JPanel myPanel; private int num; public void init() { setBackground(Color.lightGray); inputLabel = new JLabel("Enter number:"); playVariable = new JTextField(4); doIt = new JButton("Do it!"); doIt.addActionListener(this); myPanelClass myPanel = new myPanelClass(); myPanel.add(inputLabel); myPanel.add(numVariable); myPanel.add(doIt); getContentPane().add(myPanel); } public class myPanelClass extends JPanel { public void paintComponent(Graphics page) { super.paintComponent(page); if (num <= 0) return; if (num == 1) { page.setColor(Color.blue); page.fillOval(50, 50, 20, 20); } else if (num == 2) { page.setColor(Color.green); page.fillRect(50, 50, 40, 20); } else if (num == 3) { page.setColor(Color.gray); page.drawLine(50,50,120,50); } } public void actionPerformed(ActionEvent event) { numAsString = numVariable.getText(); if (numAsString.length() <= 0) return; num = Integer.parseInt(numAsString); repaint(); } }

I just edited my post - seems I came up with the same thing somehow :-). I will put a bit more thinking into what I did (and you suggested) and will go from there :-). Thanks a lot!

Thanks for the quick reply. I am a complete novice (read only 3 chapters from a Java book) in this so my questions may seem weird. I know I need to read more before going into "difficult" things like this but just want to try to see how it works and then will understand it completely :-)

I changed to JApplet and JTextField.

OK, the "Instead of adding components to the applet, add them to a JPanel and then add the panel instance to the applet using the JApplet#getContentPane()#add method" part first:

1. I added "private JPanel myPanel;" in line 5
2. I replaced lines 25, 26 and 27 with "myPanel.add(inputLabel); myPanel.add(sizeVariable); myPanel.add(doButton);

The "You should be overriding the paintComponent(Graphics g) method of the JPanel instead of paint " I kind of understand as "I should not be adding anything to the paint method of the JApplet itself but instead to the paintComponent method of the JPanel. I tried and added this at the end of my code:

public class TestPanelClass extends JPanel { public TestPanelClass() { setPreferredSize(new Dimension(200, 200)); } public void paintComponent(Graphics page) { super.paintComponent(page); page.setColor(Color.red); page.fillOval(10, 10, 20, 20); } }

Then "TestPanelClass myPanel = new TestPanelClass();" before the add() operations and "getContentPane().add(myPanel);" after the add operations of line 25-27;

This compiles and I see the red circle. But I do not know how to use all this in the actionPerformed part of the program...


edit: I think I got this :-). I declared the variable size at the begining of the class and then in actionPerformed was calling redraw() and in the declaration of my class the size was used to set the color of the circle. I don't understand exactly what I did but it looks promising.

Hello!

I am trying to write a program that reads the number from a TextField and draws a circle with that size and color depending on the size (e.g. if size is between 10 and 20 - make it red, otherwise green). I was able to display the input box and a button to perform the action:

import java.applet.*; import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Circle extends Applet implements ActionListener { private JLabel inputSize; private JButton doButton; private TextField sizeVariable; private String sizeAsString; public void init() { inputSize = new JLabel("Enter size:"); sizeVariable = new TextField(4); doButton = new JButton("Lets do it!"); doButton.addActionListener(this); add(inputSize); add(sizeVariable); add(doButton); } public void actionPerformed(ActionEvent event) { sizeAsString = sizeVariable.getText(); if (sizeAsString.length() <= 0) return; System.out.println(sizeAsString); int size= Integer.parseInt(sizeAsString); if (size == 10) { System.out.println("green"); // somehow print a green circle } else if (size == 20) { System.out.println("red"); // somehow print a red circle } else { System.out.println("yellow"); // make it a yellow circle } } }

But a few problems show up:
1. if I add a

public void paint (Graphics page) { // something }

everything but the input box disappears.

2. I am not sure how to "draw" from within the actionPerformed context as it is not like the paint(Graphics page) as I don't "have" a page :-)


Thanks in advance for all and any help :-)