about layouts in simple calculator

Question

hi there i am trying to make a calculator with coding sizes,layouts etc. by myself (trying to not use NetBeans and it is not a homework). but i am facing with a problem about empty spaces. i have a TextArea and Buttons but as you can see below i cant handle this space problem. here is my code,

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSeparator;
import javax.swing.JTextArea;

public class calculator extends JFrame {

    public calculator(){

        initComponents();

    }

    private void initComponents(){

        JPanel panelScreen = new JPanel(new GridLayout(0,1));

        JTextArea screen = new JTextArea();
        panelScreen.add(screen);

        JFrame frame = new JFrame("CALCULATOR");
        frame.setDefaultCloseOperation(EXIT_ON_CLOSE);

        JPanel panelButtons = new JPanel(new GridLayout(3,3));

        JButton oneButton = new JButton("1");
        panelButtons.add(oneButton);

        JButton twoButton = new JButton("2");
        panelButtons.add(twoButton);

        JButton threeButton = new JButton("3");
        panelButtons.add(threeButton);

        JButton fourButton = new JButton("4");
        panelButtons.add(fourButton);

        JButton fiveButton = new JButton("5");
        panelButtons.add(fiveButton);

        JButton sixButton = new JButton("6");
        panelButtons.add(sixButton);

        JButton sevenButton = new JButton("7");
        panelButtons.add(sevenButton);

        JButton eightButton = new JButton("8");
        panelButtons.add(eightButton);

        JButton nineButton = new JButton("9");
        panelButtons.add(nineButton);

        frame.getContentPane().add(panelScreen, BorderLayout.NORTH);
        //frame.getContentPane().add(new JSeparator(), BorderLayout.CENTER);
        frame.getContentPane().add(panelButtons, BorderLayout.SOUTH);
        frame.setBounds(50, 50, 500, 500);
        frame.setResizable(false);
        //frame.pack();
        frame.setVisible(true);


    }


    public static void main(String[] args) {

        new calculator();

    }

}

and this the picture of programme;

i appreciate if you can help me. anyway thanks :)

Answer 1

A few suggestions:

1. Don't set the JFrame's size, and in fact don't set any sizes.
2. Call pack to all the components to set their own sizes.
3. If you want the buttons bigger, consider changing the size of their fonts.

e.g.,

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GridLayout;

import javax.swing.*;

public class Calc2 {
   public static final String[][] BUTTON_TEXTS = {
      {"7", "8", "9", "+"},
      {"4", "5", "6", "-"},
      {"1", "2", "3", "*"},
      {"0", ".", "/", "="}
   };
   public static final Font BTN_FONT = new Font(Font.SANS_SERIF, Font.BOLD, 24);

   private static void createAndShowGui() {
      JTextField field = new JTextField(10);
      field.setFont(BTN_FONT.deriveFont(Font.PLAIN));
      JPanel btnPanel = new JPanel(new GridLayout(BUTTON_TEXTS.length,
            BUTTON_TEXTS[0].length));

      for (int i = 0; i < BUTTON_TEXTS.length; i++) {
         for (int j = 0; j < BUTTON_TEXTS[i].length; j++) {
            JButton btn = new JButton(BUTTON_TEXTS[i][j]);
            btn.setFont(BTN_FONT);
            btnPanel.add(btn);
         }
      }

      JPanel mainPanel = new JPanel(new BorderLayout());
      mainPanel.add(field, BorderLayout.PAGE_START);
      mainPanel.add(btnPanel, BorderLayout.CENTER);


      JFrame frame = new JFrame("Calc2");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}