Java Swing Tutorial Day 2

G'Day Again fellow replers. It seems that there really is some people who enjoyed learning java swing.
So I will continue teaching it!

Swing!

(One of) The java libraries for making Cross-platform Desktop Applications.

Previous Tutorials:

• Day 1: We learned how to make a JFrame and button there!

The topics for today are...

JCOMPONENTS

JComponents are components included in the java library.

Unsurprisingly, hey all start with a J

We will be going over more JComponents in the future, but for today, we will be going over the following.

• JCheckBox
• JLabel
• JTextField

First up...

JCheckBox!

A checkbox is just a box which can be selected or not be selected indicated with a check. It is Extremely simple to use.

How to use JCheckBox!:

import javax.swing.*;
import java.awt.*;

public class Main{

	private void setUpFrame(){

		//Set up frame...

		//JCheckBox stuff!


		JCheckBox box = new JCheckBox("My first JCheckBox!");
		//Creating an instance of JCheckBox	

		box.addItemListener(new ItemListener(){
	
			@Override
			public void itemStateChanged(ItemEvent e){

				if(box.isSelected()){// Use box.isSelected to check whether or not the box is selected

					System.out.println("The box was selected!");

				}else{

					System.out.println("The box was unselected!");					

				}								

			}					

		});

		/*

			Selecting or Unselecting a box fires an ItemEvent so we need an ItemListener

			Listeners are how you listen to events fired by components in the GUI. Almost every components has a specific event attached to it. When you add a Listener, what ever is in the overridded method is called.
			
			In the last tutorial, we used an ActionListener to listen for ActionEvents fired by a button			

		*/

		
		frame.getContentPane().add(box);

		frame.setLocationRelativeTo(null);
		frame.setVisible(true);		

	
	}

	public static void main(String[] args){

		setUpFrame();	

	}	

}

This is how simple it is to use a JCheckBox. You can get all the information about the methods and constructors here.

Up next...

JLabel!

A JLabel is just a label which holds a string of characters and you can print that almost anywhere in a frame.
It is usually used to show the user information

Here is how to create a JLabel and to use it.

Note: From here on out, I will not include the code other than what is required(The JComponent we are going over)

JLabel label = new JLabel("My first JLabel!");

Button b = new Button("Click me to change the text");

b.addActionListener(new ActionListener(){

	public void actionPerformed(ActionEvent e){
		String[] phrases = {"My first JLabel!", "Hello!", "The text Changed!", "Help me!", "repl is amazing"};
		
		System.out.println(label.getText());
		//label.getText() gets the current text in the JLabel

		String newText = phrases[(int)(Math.random()*phrases.length)];
		//Choosing a random phrase
		
		label.setText(newText);		
		//Use this to set the text!

	}

});

frame.add(button);
frame.add(label);

That is how simple it is to use a JLabel! You can use that to print information to the gui!

Check out the doc here!

And now the final JComponent we will be going over...

JTextField!

A JTextField is pretty much a text field. The user can type in information in it.

A text field also fires action events when the user presses enter.

In this example, pretend we are writing a chat client...

JTextField message = new JTextField(20);
//The 20 means 20 columns. The can be one char per column

message.addActionListener(new ActionListener(){
	
	public void actionPerformed(ActionEvent e){

		sendMessage(message.getText());
		//sendMessage is just a seperate method which sends the message to the server.
		//message.getText() returns a string. That string is the text currently in the text  field

		message.setText("Type message");
		//This sets the text in the field to be whatever is inside the "". 

		message.selectAll();
		//Selects all the text that is currently in the message.		

		message.requestFocus();
		//requests focus so that the user can continue to type without having to press the text field again	

	}
});

/*
There is another noteable method for JTextFields and the is...

[yourtextfield].setEditable(boolean isEditable);

You type a boolean as a parameter and this sets it to be editable or not.

*/

That is how simple it is to use a JTextField! Incredibly easily!
Check out the doc as well!

Well, that is it for this tutorial!

I hope you enjoyed and learned something new. You can try these JComponents in a new java swing project.

Please give feedback in the comments.

Thank you!