GUI's

A window is a “JFrame”

• Dimensions are in pixels
  • (0,0) is at the top left (like Godot)
• Widgets are the components:
  • TextLabels
    • Will display words
  • Buttons
  • TextField
    • Will allow user input
  • TextArea
  • CheckBox

• Output can be a label (most common)
• All widgets are rectangular and they are placed via the top-left corner’s position

E.g: a label is 200 by 50. The Frame is 500 by 500. How do we center it?

• y: 250 - 25 = 225 y
• x: 250 - 100 = 150 x
• Rect Coords: (150, 225)

• Main isn’t used very much
• If we want to make a Gui, make a new file called frmMyGui
  • All forms will start with “frm”
  • All the imports will be copy-pasted
  • Dw about what extends and implements mean; really.
  • Instance the GUI inside of main:
  • 

here is the file frmMyGui.java

Frame methods

Inside of frmMyGUI’s constructor

Instancing custom colors

Defining new widgets on a frame

Declare it first

public class frmMyFrame extends JFrame implements ActionListener 
{
	// Declare variable
	JLabel lblTitle;
	JTextField txtName;
	JButtom btnEnter;
	
	public frmMyFrame() 
	{
		setLayout(null); // This will give "full control" over where labels go
		
		// Instance it
		lblTitle = new JLabel("Welcome to my GUI");
		// These can now be controlled b/c setLayout is null.
		lblTitle.setSize(200, 50);
		lblTitle.setLocation(150, 0);
		// Required to see the widget
		add(lblTitle);  
 
 
		// Setting up a text field
		txtName = new JTextField(); // Nothing required to instance
		txtName.setLocation(150, 50);
		txtName.setSize(100, 50);
		add(txtName);
		
 
		// Lastly, a button for example
		btnEnter = new JButton("Enter");
		btnEnter.setSize(150, 200);
		btnEnter.setLocation(100, 50);
		add(btnEnter;)
	}
}

If two widgets are on the same spot, they're cover eachother up! Be careful about that

Coding the GUI’s

• All buttons have “Actions”
• Before adding a button, you need these 2 lines of code to make the button do something.

 
public frmMyFrame() {
	btnEnter = new JButton("Enter");
	btnEnter.setSize(150, 200);
	btnEnter.setLocation(100, 50);	
	// New lines
	btnEnter.setActionComment("enter");
	btnEnter.setActionListener(this);
	// Remember to add
	add(btnEnter;)
}
 
public void actionPerformed(ActionEvent e) {
	if (e.getActionComment.equals("enter")) {
		// Code is triggered when the button is pressed
	}
}

Getting text from TextLabel

// It's this simple! txtName is a JTextLabel
String text = txtName.getText();
 
double dblValue = 10.41;
txtName.setText("" + dblValue); // Set text always takes in a string. A double is not a string, so we concatenate with the "+"

Misc things

• JOptionPane.showMessageDialog(null, "Message") will display a ⓘ message