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Java Swing Tutorial Day 2. LEARN HOW TO MAKE A GUI


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!


(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 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.

First up...


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...


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...


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!

2 years ago
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Oh, ok. thx. (I'm new at this!)

1 year ago