Create Simple Calculator using JAVA GUI

Here I give you a simple program to create Calculator using Java GUI. Please use this website as a reference link if you want to copy and paste this program.
If any question, don't be hesitate to leave a comment or contact my email.

package week09;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.LineBorder;

/**@author Novida Wayan Sari (1606954930)
 * @version 20161127 07:35PM
 * This class is Calculator class which is used to count a simple mathematics operation
 * such as plus, minus, multiply and divide.
 * This application is created to complete weekly task of Dasar-Dasar Pemrograman lecturing subject.
 * This application uses JPanel as for the main component of GUI
 * */

public class Calculator extends JPanel implements ActionListener {
    private static final int WIDTH = 420; //constant of frame width
    private static final int HEIGHT = 252; //constant of frame height
    private JMenuBar menuBar; //Menu Bar (File, Help) <-- I do not have any idea to fill up the content
    private JMenu fileMenu, helpMenu; //Referring Menu Bar, the content of menu bar
   
    //mainPanel is a JPanel contains of main components except Menu Bar
    //bottomPanel is a JPanel container of angkaPanel and operatorPanel
    //angkaPanel is a JPanel container of all number button and "+" and "-" [Grid Layout]
    //operatolPanel is a JPanel container of all operators button except "+" and "-" [Grid Layout]
    private JPanel mainPanel, bottomPanel, angkaPanel, operatorPanel;
    //-------------------------------------------------------------------------------------------------
    private JButton[] btnAngka; //Array of number button {"0","1","2","3","4","5","6","7","8","9"}
    private JButton[] btnControl; //Arrays of control button {"Backspace","C"}
    private JButton[] btnOperator; //Array of operator button {"+","-","/","*","="}
    private JTextField input; //Text field of input
    private Color bckColor, mainColor, inputColor, textColor; //Colors used to make background, foreground color in this application
    private float numb1 = 0; //variable which is used to save temporary value inputed by user
    private String oldOperator = ""; //variable which is used to save temporary operator inputed by user
    private boolean status = false; //the status to show if the operation is end
   
    /*constructor
     * */
    public Calculator(){
        this.bckColor = new Color(205,92,92); //Background Color
        this.mainColor = new Color(128,0,0); //Button Color
        this.inputColor = new Color(255,182,193); //Textfield background color
        this.textColor = new Color(255,182,193); //Text of text field color
       
        /*Main Panel uses Flow Layout which contains of Menu Bar and Main Panel*/
        super.setLayout(new FlowLayout());
        super.setPreferredSize(new Dimension(this.WIDTH, this.HEIGHT));
        super.setBackground(bckColor);
        super.setForeground(Color.WHITE);
       
        /*----------------- Menu Bar ------------------------------------------------*/
        this.menuBar = new JMenuBar();
        this.menuBar.setPreferredSize(new Dimension(this.WIDTH-20, 30));
        this.menuBar.setLocation(10, 0);
        this.menuBar.setBackground(bckColor);
        this.menuBar.setForeground(Color.white);
        this.fileMenu = new JMenu("File");
        this.helpMenu = new JMenu("Help");
        this.menuBar.add(fileMenu);
        this.menuBar.add(helpMenu);
        /*----------------- End of Menu Bar -----------------------------------------*/
       
        /*----------------- Input -----------------------------------------------------------------------------*/
        this.input = new JTextField();
        this.input.setPreferredSize(new Dimension(this.WIDTH-20, 30));
        this.input.setBackground(inputColor);
        this.input.setForeground(bckColor);
        this.input.setHorizontalAlignment(JLabel.RIGHT);
        this.input.setBorder(new LineBorder(bckColor));
        this.input.setBorder(BorderFactory.createCompoundBorder(this.input.getBorder(), BorderFactory.createEmptyBorder(5, 5, 5, 5)));
        this.input.setFont(new Font(this.input.getFont().getName(),Font.BOLD,this.input.getFont().getSize()));
        this.input.setEditable(false);
        this.input.setText("0");
        /*---------------- End of Input-------------------------------------------------------------------------*/
       
        /*---------------- Number Button -----------------------------------------------------------*/
        this.btnAngka = new JButton[10];
        this.btnControl = new JButton[2];
        this.btnOperator = new JButton[6];
       
        int colNum = 4;
        for(int i=0;i<10;i++){
            this.btnAngka[i] = new JButton(""+i);
            this.btnAngka[i].setPreferredSize(new Dimension((this.WIDTH-20)/colNum,30));
            this.btnAngka[i].setBackground(mainColor);
            this.btnAngka[i].setForeground(textColor);
            this.btnAngka[i].setBorder(new LineBorder(bckColor));
            this.btnAngka[i].addActionListener(this);
        }
        /*--------------- End of Number Button ----------------------------------------------------*/
       
        /*--------------- Control Button ----------------------------------------------------------*/
        this.btnControl[0] = new JButton("Backspace");
        this.btnControl[1] = new JButton("C");
       
        for(int i=0;i<2;i++){
            this.btnControl[i].setPreferredSize(new Dimension((this.WIDTH-20)/colNum,30));
            this.btnControl[i].setBackground(mainColor);
            this.btnControl[i].setForeground(textColor);
            this.btnControl[i].setBorder(new LineBorder(bckColor));
            this.btnControl[i].addActionListener(this);
        }
        /*--------------- End of Control Button ---------------------------------------------------*/
       
        /*--------------- Operator Button ---------------------------------------------------------*/
        this.btnOperator[0] = new JButton("+");
        this.btnOperator[1] = new JButton("-");
        this.btnOperator[2] = new JButton("/");
        this.btnOperator[3] = new JButton("*");
        this.btnOperator[4] = new JButton(".");
        this.btnOperator[5] = new JButton("=");
       
        for(int i=0;i<6;i++){
            this.btnOperator[i].setPreferredSize(new Dimension((this.WIDTH-20)/colNum,30));
            this.btnOperator[i].setBackground(mainColor);
            this.btnOperator[i].setForeground(textColor);
            this.btnOperator[i].setBorder(new LineBorder(bckColor));
            this.btnOperator[i].addActionListener(this);
        }
        /*-------------- End of Operator Button --------------------------------------------------*/
       
        //------------ BACKSPACE BUTTON -----------------------------------------------------------
        this.btnControl[0].setPreferredSize(new Dimension((2*(this.WIDTH-20))/colNum,30));
        this.btnControl[0].setLocation(10,70);
        this.btnControl[0].setBackground(mainColor);
        this.btnControl[0].setForeground(textColor);
        this.btnControl[0].setBorder(new LineBorder(bckColor));
        //------------ END OF BACKSPACE -----------------------------------------------------------
       
        //------------ C BUTTON -----------------------------------------------------------
        this.btnControl[1].setPreferredSize(new Dimension((this.WIDTH-20)/colNum,30));
        this.btnControl[1].setBackground(mainColor);
        this.btnControl[1].setForeground(textColor);
        this.btnControl[1].setBorder(new LineBorder(bckColor));
        //------------ END OF C BUTTON -----------------------------------------------------------
       
        /*------------ Bottom Panel -------------------------------------------------------------*/
        this.bottomPanel = new JPanel();
        this.bottomPanel.setPreferredSize(new Dimension(this.WIDTH-20,120));
        this.bottomPanel.setLayout(new BorderLayout());
        /*------------ of Bottom Panel ----------------------------------------------------------*/
       
        /*------------ Panel of number button -----------------------------------------------------*/
        this.angkaPanel = new JPanel();
        this.angkaPanel.setPreferredSize(new Dimension((3*(this.WIDTH-20))/4,120));
        this.angkaPanel.setLayout(new GridLayout(4,3));
        for(int i=0;i<3;i++){
            for(int j=0;j<3;j++){
                this.angkaPanel.add(this.btnAngka[(2-i)*3+1+j]);
            }
        }
   
        this.angkaPanel.add(this.btnOperator[0]);
        this.angkaPanel.add(this.btnAngka[0]);
        this.angkaPanel.add(this.btnOperator[1]);
        /*------------ End of Panel of number button ---------------------------------------------------*/
       
        this.bottomPanel.add(this.angkaPanel, BorderLayout.WEST);
       
        this.operatorPanel = new JPanel();
        this.operatorPanel.setPreferredSize(new Dimension((this.WIDTH-20)/4,120));
        this.operatorPanel.setLayout(new GridLayout(4,1));
       
        for(int i=0;i<4;i++){
            this.operatorPanel.add(this.btnOperator[i+2]);
        }
       
        this.bottomPanel.add(this.operatorPanel, BorderLayout.EAST);
       
        /*------------ insert all components to main Panel and add it to this class ---------------------*/
        this.mainPanel = new JPanel();
        this.mainPanel.setLayout(new BorderLayout());
        this.mainPanel.setBackground(bckColor);
            /*---------------------- Main Panel uses Border Layout ------------*/
        this.mainPanel.add(this.input, BorderLayout.NORTH);
        this.mainPanel.add(this.btnControl[0], BorderLayout.WEST);
        this.mainPanel.add(this.btnControl[1], BorderLayout.EAST);
        this.mainPanel.add(this.bottomPanel, BorderLayout.SOUTH);
            /*-----------------------------------------------------------------*/
        super.add(menuBar);
        super.add(mainPanel);
        /*-----------------------------------------------------------------------------------------------*/
    }
   
   
    @Override
    public void actionPerformed(ActionEvent evt) {
        // TODO Auto-generated method stub
        if(evt.getSource() instanceof JButton){
            String btnText = ((JButton)evt.getSource()).getText();
            String pattern = "[0-9]|[.]";
            if(btnText == "Backspace"){
                /*If the button pressed is backspace, then it will erase the last digit of shown inputed number*/
                if(!this.input.getText().equals("")){
                    /*if there is digit in the last, then system should check if it is not zero (integer or decimal)*/
                    if(this.input.getText().equals("0.")){
                        this.input.setText("0");
                    }else{
                        /*if there is digit in the last, then system should check if previous digit is exist*/
                        if(this.input.getText().substring(0, this.input.getText().length()-1).equals("")){
                            this.input.setText("0");
                        }else{
                            this.input.setText(this.input.getText().substring(0, this.input.getText().length()-1));
                        }
                    }
                }
                this.status = false; //it shows that there is no temporary operation, backspace doesn't make any calculation process
            }else if(btnText == "C"){
                /*C will clear all shown number and change it into zero ------------------
                 * it also will clean up the history of number and operator inputed by the user
                 * */
                this.input.setText("0");
                this.numb1 = 0;
                this.oldOperator = "";
                this.status = false;
            }else if(btnText.matches(pattern)){
                if(btnText.equals(".") && this.input.getText().equals("0")){
                    /*If only zero shown in screen, and the user presses point to input decimal number -------------*/
                    this.input.setText("0.");
                }else{
                    if(this.status == false){
                        if(this.input.getText().equals("0")){
                            /*If only zero show in screen, and the user presses any number, the zero in the first character shouldn't be shown*/
                            this.input.setText(btnText);
                        }else{
                            /*If the first number isn't zero, then the system only append pressed number*/
                            this.input.setText(this.input.getText()+btnText);
                        }
                    }else{
                        this.input.setText(btnText);
                    }
                }
               
                this.status = false;
            }else{
                try{
                    /*Every single time the user presses operator button, then the system should do calculation based on
                     *history of number and operator user pressed
                     **/
                    float result = this.count();
                    if(result == Math.floor(result)){
                        /*If the result of calculation can be figured out into integer form, then the system prioritize it first */
                        this.input.setText(""+(int)result);
                    }else{
                        this.input.setText(""+result);
                    }
                    this.status = true;
                }catch(NumberFormatException e){
                    JOptionPane.showMessageDialog(null, "There was an error occured. Please restart the application and then try again!");
                }
               
                if(btnText.equals("=")){
                    /*= button will shows the result and erase the history of number and operator inputed by the user such C button does */
                    this.oldOperator = "";
                    this.numb1 = 0;
                }else{
                    /*The system saves the operator as temporary operator to be executed in next operator pressed*/
                    this.oldOperator = btnText;
                }
            }
        }
    }
   
    public float count(){
        switch(this.oldOperator){
            case "+":this.numb1=this.numb1+Float.valueOf((this.input.getText()));break;
            case "-":this.numb1=this.numb1-Float.valueOf((this.input.getText()));break;
            case "/":this.numb1=this.numb1/Float.valueOf((this.input.getText()));break;
            case "*":this.numb1=this.numb1*Float.valueOf((this.input.getText()));break;
            case "":this.numb1=Float.valueOf((this.input.getText()));break;
        }
        return this.numb1;
    }
   
    public static void main(String[] arg){
        JFrame frame = new JFrame("Calculator");
        frame.setSize(Calculator.WIDTH, Calculator.HEIGHT);
        frame.setLocation(150, 150);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       
        Calculator calc = new Calculator();
        frame.add(calc);
        frame.setVisible(true);
    }

}

Posted By Novida10:33 PM

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How to install Eclipse in Ubuntu

Hallo, guys!
it's been long time I didn't update this blog and here I will share you how to install Eclipse using Ubuntu. This is my first experience in using Operating System except Windows. We all know well that to install application in windows is not a big issue, since the user can easily install it by hit 'next' or 'OK' button. Haha.

Let's download eclipse installer package in eclipse website. In this case, please use tar.gz eclipse installer file.

1. go to the folder in which the tar.gz file is stored, in this case you have to go to Downloads folder cd Downloads
2. lets unzip tar file using tar -zxvf [eclipse file name]
3. Extract the file and copy to /opt folder sudo mv [extracted eclipse file] /opt
4. Create desktop file and install it gedit eclipse.desktop
5. Copy the following eclipse dekstop configuration file:

   [Desktop Entry]
   Name=Eclipse 
   Type=Application
   Exec=env UBUNTU_MENUPROXY=0 eclipse44
   Terminal=false
   Icon=eclipse
   Comment=Integrated Development Environment
   NoDisplay=false
   Categories=Development;IDE;
   Name[en]=Eclipse
   

    

Posted By Novida5:57 PM

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