Let's make a calculator application with Java ~ Create a display area in the window

The Java development environment uses OpenJDK 11.0.4 installed on Ubuntu 18.04.

In Previous article, the application window was displayed. This time we will create a display area inside the window. In the previous code, the goal was to display the application window using Jframe for the time being, so I wrote all the code in the main method, but considering the ease of writing and reading in the future, I decided to use the MyFrame method. Created and instantiated in the main method.

MyFrame.java

import javax.swing.JFrame;

public class MyFrame extends JFrame{
    public static void main(String[] args) {
        MyFrame frame = new MyFrame("Java Swing test");
        frame.setVisible(true);
    }

    MyFrame(String title){
        setTitle(title);
        setSize(500, 600);                                //Window size(width,height)
        setLocationRelativeTo(null);                      //Display window in the center of the screen
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);   // x(X)Quit the application with the button.
    }
}

JavaSwing has a layered structure in which the base JFrame and panels and buttons are placed on it. Since JFrame only displays a window, let's create a panel that displays the numbers required for the calculator app.

MyFrame.java

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.BevelBorder;
import java.awt.FlowLayout;
import java.awt.Dimension;
import java.awt.Color;
import java.awt.Container;



public class MyFrame extends JFrame{
    public static void main(String[] args) {
        MyFrame frame = new MyFrame("Java Swing test");
        frame.setVisible(true);
    }

    MyFrame(String title){
        setTitle(title);
        setSize(500, 600);                                //Window size(width,height)
        setLocationRelativeTo(null);                      //Display window in the center of the screen
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);   // x(X)Quit the application with the button.

        setLayout(new FlowLayout());

        JPanel panelDisplay = new JPanel();                         //Panel instantiation
        panelDisplay.setPreferredSize(new Dimension(500, 60));      //Panel size
        panelDisplay.setBackground(new Color(51, 51, 51));          //Color code#333333
        BevelBorder border = new BevelBorder(BevelBorder.RAISED);
        panelDisplay.setBorder(border);

        Container contentPane = getContentPane();
        contentPane.add(panelDisplay);
    }
}

The execution result is as shown in the figure below. This time, the panel size was set to 500 x 60 and the color was set to # 333333. After this, there are also arrangements such as buttons, so there may be changes in size etc.

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Try making a calculator app in Java