Question

I’m new in Java and I’m finding it hard to implement a GUI here unlike in Visual Basic.

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


public class CalculatorGui extends JFrame{
    private static final int WIDTH = 250;
    private static final int HEIGHT = 250;

    private JTextField enterTextField;

    private JButton sevenB, eightB, nineB, divideB, fourB, fiveB, sixB, multiplyB, oneB, twoB, threeB, subtractB, zeroB, dotB, equalsB, addB;

    public CalculatorGui() {
        setTitle("Calculator");
        setSize(WIDTH, HEIGHT);

        setLayout(new GridLayout(4, 4));

        enterTextField = new JTextField(30);

        sevenB = new JButton("7");
        eightB = new JButton("8");
        nineB = new JButton("9");
        divideB = new JButton("/");
        fourB = new JButton("4");
        fiveB = new JButton("5");
        sixB = new JButton("6");
        multiplyB = new JButton("*");
        oneB = new JButton("1");
        twoB = new JButton("2");
        threeB = new JButton("3");
        subtractB = new JButton("-");
        zeroB = new JButton("0");
        dotB = new JButton(".");
        equalsB = new JButton("=");
        addB = new JButton("+");

        /*JPanel dataPanel = new JPanel();
        JPanel buttonPanel = new JPanel();

        FlowLayout flowCenter = new FlowLayout(FlowLayout.RIGHT);
        GridLayout aGrid = new GridLayout(4, 4);

        buttonPanel.setLayout(flowCenter);
        dataPanel.setLayout(aGrid);


        dataPanel.add(enterTextField);
        buttonPanel.add(sevenB);
        buttonPanel.add(eightB);
        buttonPanel.add(nineB);
        buttonPanel.add(divideB);
        buttonPanel.add(fourB);
        buttonPanel.add(fiveB);
        buttonPanel.add(sixB);
        buttonPanel.add(multiplyB);
        buttonPanel.add(oneB);
        buttonPanel.add(twoB);
        buttonPanel.add(threeB);
        buttonPanel.add(subtractB);
        buttonPanel.add(zeroB);
        buttonPanel.add(dotB);
        buttonPanel.add(equalsB);
        buttonPanel.add(addB);

        add(dataPanel, BorderLayout.NORTH);
        add(buttonPanel, BorderLayout.CENTER);*/

        //add(enterTextField);
        add(sevenB);
        add(eightB);
        add(nineB);
        add(divideB);
        add(fourB);
        add(fiveB);
        add(sixB);
        add(multiplyB);
        add(oneB);
        add(twoB);
        add(threeB);
        add(subtractB);
        add(zeroB);
        add(dotB);
        add(equalsB);
        add(addB);

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);

    }

    public static void main(String[] args) {

        CalculatorGui calcu = new CalculatorGui();

    }

}

It runs but I need to put a text field right before those buttons (numbers). The text field should flow and will not be enlarged when the window is maximized (unlike the 4×4 buttons). I’ve tried JPanel (see comments) but it outputs a horrible design. P

Answer 1

Here you go, with some rules to follow while building GUI (rules):
Do not subclass AWT/Swing/X Components for application needs

import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class CalculatorGui {

    private static final int WIDTH = 250;
    private static final int HEIGHT = 250;
    private JTextField enterTextField;
    private JButton sevenB, eightB, nineB, divideB, fourB, fiveB, sixB, multiplyB, oneB, twoB, threeB, subtractB, zeroB, dotB, equalsB, addB;

    public CalculatorGui() {
        JFrame frame = new JFrame("Calculator");
        frame.setTitle("Calculator");
        frame.setSize(WIDTH, HEIGHT);

        JPanel buttonPanel = new JPanel(new GridLayout(4, 4));        
        enterTextField = new JTextField();       

        frame.add(enterTextField, BorderLayout.NORTH);

        sevenB = new JButton("7");
        eightB = new JButton("8");
        nineB = new JButton("9");
        divideB = new JButton("/");
        fourB = new JButton("4");
        fiveB = new JButton("5");
        sixB = new JButton("6");
        multiplyB = new JButton("*");
        oneB = new JButton("1");
        twoB = new JButton("2");
        threeB = new JButton("3");
        subtractB = new JButton("-");
        zeroB = new JButton("0");
        dotB = new JButton(".");
        equalsB = new JButton("=");
        addB = new JButton("+");

        buttonPanel.add(sevenB);
        buttonPanel.add(eightB);
        buttonPanel.add(nineB);
        buttonPanel.add(divideB);
        buttonPanel.add(fourB);
        buttonPanel.add(fiveB);
        buttonPanel.add(sixB);
        buttonPanel.add(multiplyB);
        buttonPanel.add(oneB);
        buttonPanel.add(twoB);
        buttonPanel.add(threeB);
        buttonPanel.add(subtractB);
        buttonPanel.add(zeroB);
        buttonPanel.add(dotB);
        buttonPanel.add(equalsB);
        buttonPanel.add(addB);

        frame.add(buttonPanel, BorderLayout.CENTER);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        CalculatorGui calcu = new CalculatorGui();
    }
}

I would suggest you to use WindowsBuilder Pro after a good manual practice with some layouts and components