Java - Unable to move position of JTextField

Question

I am trying to create a new JTextField in my Jframe. I want to play around with the positioning of the textfield. I tried using setBounds and setLocation to change the position of the text box but it doesn't change the location of the text box at all.

This is my code:

public class GUI_Tutorial extends JFrame {

    public static void main(String[] args) {

        GUI_Tutorial frame = new GUI_Tutorial();
        frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
        frame.setSize(1000, 800);
        frame.setVisible(true);
        frame.setTitle("Calculator");
        frame.setLayout(new FlowLayout());

    }

    public GUI_Tutorial() {
        //frame.setLayout(new FlowLayout());
        JTextField num1;
        num1 = new JTextField(10);
        add(num1);
        num1.setVisible(true);
        num1.setLocation(5, 5);     
    } 
}

May I know what am I doing wrong?

Answer 1

Your problem is one of layout managers. When you add a component to a container, the layout manager will dictate where the component will go. A JFrame's contentPane (the JFrame sub-container that holds its components) uses a BorderLayout by default, and items added to this container in a default manner will fill the central portion of the container, will fill it completely if nothing else is added to other BorderLayout locations.

Possible solutions for placing items:

• The worst suggestion, use a null layout. You would do this by calling getContentPane().setLayout(null);. But when you do this, you the programmer are 100% responsible for the exact position and size of all components added. This leads to hard to maintain GUI's that might not even work on other platforms -- so don't do this.
• Use a GUI builder to help build your program: this has definite advantages, one being that it shields you from having to directly understand the layout managers, but this also is a disadvantage, because once you run into edge cases (and you usually will and quickly) that knowledge is essential. My own view is to initially avoid using this so as to better understand the layout managers, and then once you're familiar with the managers, then sure use this as needed.
• Better is to learn and experiment with the layout managers, and Borders, playing with placement of components. Remember that you can nest containers (usually JPanels) and each can be given its own layout manager, allowing for complex GUI's that are created easily and maintained easily.

Note that

• (again) JFrames (actually their contentPanes), JDialogs, and other top-level windows use BorderLayout by default, that JPanels use FlowLayout by default, that JScrollPanes use their own specialty layout, one that you will likely never want to muck with, and that most other components/containers, such as JComponent, JLabel,... have null layouts by default.
• Best resource is the tutorial: Lesson: Laying Out Components Within a Container
• Borders can also be useful here, especially the EmptyBorder which can allow you to put a blank buffer zone around your components.
• Start playing with the simpler layout managers, FlowLayout, BorderLayout, GridLayout, then BoxLayout, before moving to the more complex

Answer 2

Try removing frame.setLayout(new FlowLayout());. You'll then need to use num1.setBounds(x, y, width, height) rather than setLocation()

But, as other users have pointed out, you should be using a layout manager. Read up on the different layouts and choose the best one for your GUI.