I wrote this small basic Calculator Swing Program for my CS202 Assignment at Cal State LA. I thought to share with you all.
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package lab8; import java.awt.BorderLayout; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.FocusEvent; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JTextField; public class Calculator extends JFrame implements ActionListener{ private static final long serialVersionUID = 1L; int intState; String strOperand1; String strOperand2; String strOperation; boolean blnDot = false; JTextField jtxtfieldDisplayBar; JFrame jfCalculator = this; public Calculator(){ super("Simple Calculator"); this.setSize(300, 175); this.setLocationRelativeTo(null); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setResizable(false); FocusEvent focusEvent = new FocusEvent(this, FocusEvent.FOCUS_GAINED); dispatchEvent(focusEvent); intState = 0; strOperand1 = ""; strOperand2 = ""; strOperation = ""; JPanel jpMain = new JPanel(); jpMain.setLayout(new BorderLayout()); this.add(jpMain); JPanel jpNorth = new JPanel(); jpNorth.setLayout(new BorderLayout()); jpMain.add(jpNorth, BorderLayout.NORTH); jtxtfieldDisplayBar = new JTextField("0"); jtxtfieldDisplayBar.setHorizontalAlignment(JTextField.RIGHT); jtxtfieldDisplayBar.setEditable(false); jpNorth.add(jtxtfieldDisplayBar, BorderLayout.NORTH); JPanel jpNorthSouth = new JPanel(); jpNorthSouth.setLayout(new GridLayout(1, 2)); jpNorth.add(jpNorthSouth, BorderLayout.SOUTH); JButton jbtnBackspace = new JButton("Backspace"); jbtnBackspace.addActionListener(this); jpNorthSouth.add(jbtnBackspace); JButton jbtnC = new JButton("C"); jbtnC.addActionListener(this); jpNorthSouth.add(jbtnC); JPanel jpSouth = new JPanel(); jpSouth.setLayout(new GridLayout(4, 5)); jpMain.add(jpSouth, BorderLayout.CENTER); JButton jbtn7 = new JButton("7"); jbtn7.addActionListener(this); jpSouth.add(jbtn7); JButton jbtn8 = new JButton("8"); jbtn8.addActionListener(this); jpSouth.add(jbtn8); JButton jbtn9 = new JButton("9"); jbtn9.addActionListener(this); jpSouth.add(jbtn9); JButton jbtnDivide = new JButton("/"); jbtnDivide.addActionListener(this); jpSouth.add(jbtnDivide); JButton jbtnSquareRoot = new JButton("sqrt"); jbtnSquareRoot.addActionListener(this); jpSouth.add(jbtnSquareRoot); JButton jbtn4 = new JButton("4"); jbtn4.addActionListener(this); jpSouth.add(jbtn4); JButton jbtn5 = new JButton("5"); jbtn5.addActionListener(this); jpSouth.add(jbtn5); JButton jbtn6 = new JButton("6"); jbtn6.addActionListener(this); jpSouth.add(jbtn6); JButton jbtnMultiply = new JButton("*"); jbtnMultiply.addActionListener(this); jpSouth.add(jbtnMultiply); JButton jbtnSquare = new JButton("x^2"); jbtnSquare.addActionListener(this); jpSouth.add(jbtnSquare); JButton jbtn1 = new JButton("1"); jbtn1.addActionListener(this); jpSouth.add(jbtn1); JButton jbtn2 = new JButton("2"); jbtn2.addActionListener(this); jpSouth.add(jbtn2); JButton jbtn3 = new JButton("3"); jbtn3.addActionListener(this); jpSouth.add(jbtn3); JButton jbtnSubstrate = new JButton("-"); jbtnSubstrate.addActionListener(this); jpSouth.add(jbtnSubstrate); JButton jbtnUpon = new JButton("1/x"); jbtnUpon.addActionListener(this); jpSouth.add(jbtnUpon); JButton jbtn0 = new JButton("0"); jbtn0.addActionListener(this); jpSouth.add(jbtn0); JButton jbtnPM = new JButton("+/-"); jbtnPM.addActionListener(this); jpSouth.add(jbtnPM); JButton jbtnDot = new JButton("."); jbtnDot.addActionListener(this); jpSouth.add(jbtnDot); JButton jbtnAdd = new JButton("+"); jbtnAdd.addActionListener(this); jpSouth.add(jbtnAdd); JButton jbtnEqual = new JButton("="); jbtnEqual.addActionListener(this); jpSouth.add(jbtnEqual); } public static void main(String args[]){ Calculator objSC = new Calculator(); objSC.setVisible(true); } public void actionPerformed(ActionEvent e){ String strCommand = e.getActionCommand(); if(strCommand.equals("Backspace")){ intState = 0; if(jtxtfieldDisplayBar.getText().length() == 0){ jtxtfieldDisplayBar.setText("0"); } else{ String strTemp = jtxtfieldDisplayBar.getText(); jtxtfieldDisplayBar.setText(strTemp.substring(0, (strTemp.length()-1))); strTemp = jtxtfieldDisplayBar.getText(); if(strTemp.length() == 0){ jtxtfieldDisplayBar.setText("0"); } } return; } if(strCommand.equals("C")){ intState = 0; strOperand1 = ""; strOperand2 = ""; strOperation = ""; jtxtfieldDisplayBar.setText("0"); return; } if(strCommand.equals(".")){ blnDot = true; } if(strCommand.equals("+/-")){ if(strOperand1 == ""){ intState = 1; } else{ if(jtxtfieldDisplayBar.getText().equals(strOperand1)){ intState = 1; Double dblTemp = -1 * Double.parseDouble(strOperand1); strOperand1 = "" + dblTemp; jtxtfieldDisplayBar.setText(strOperand1); return; } else if(jtxtfieldDisplayBar.getText().equals(strOperand2)){ intState = 3; Double dblTemp = -1 * Double.parseDouble(strOperand2); strOperand2 = "" + dblTemp; jtxtfieldDisplayBar.setText(strOperand2); return; } } } if(strCommand.equals("sqrt")){ intState = 1; if(Double.parseDouble(strOperand1) < 0){ System.err.println("Square Root of negative is imaginary number"); } else{ Double dblTemp = Math.sqrt(Double.parseDouble(strOperand1)); strOperand1 = "" + dblTemp; jtxtfieldDisplayBar.setText(strOperand1); return; } } if(strCommand.equals("x^2")){ intState = 1; Double dblTemp = Math.pow(Double.parseDouble(strOperand1), 2); strOperand1 = "" + dblTemp; jtxtfieldDisplayBar.setText(strOperand1); return; } if(strCommand.equals("1/x")){ intState = 1; Double dblTemp = 1 / Double.parseDouble(strOperand1); strOperand1 = "" + dblTemp; jtxtfieldDisplayBar.setText(strOperand1); return; } switch(intState){ case 0:{ if(strCommand.equals("1")){ strOperand1 = "1"; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(strCommand.equals("2")){ strOperand1 = "2"; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(strCommand.equals("3")){ strOperand1 = "3"; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(strCommand.equals("4")){ strOperand1 = "4"; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(strCommand.equals("5")){ strOperand1 = "5"; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(strCommand.equals("6")){ strOperand1 = "6"; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(strCommand.equals("7")){ strOperand1 = "7"; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(strCommand.equals("8")){ strOperand1 = "8"; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(strCommand.equals("9")){ strOperand1 = "9"; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(blnDot){ strOperand1 = "0"; intState = 1; jtxtfieldDisplayBar.setText("0"); } break; } case 1:{ if(blnDot){ strOperand1 += "."; blnDot = false; } if(strCommand.equals("1")){ strOperand1 += "1"; } if(strCommand.equals("2")){ strOperand1 += "2"; } if(strCommand.equals("3")){ strOperand1 += "3"; } if(strCommand.equals("4")){ strOperand1 += "4"; } if(strCommand.equals("5")){ strOperand1 += "5"; } if(strCommand.equals("6")){ strOperand1 += "6"; } if(strCommand.equals("7")){ strOperand1 += "7"; } if(strCommand.equals("8")){ strOperand1 += "8"; } if(strCommand.equals("9")){ strOperand1 += "9"; } if(strCommand.equals("0")){ strOperand1 += "0"; } if(strCommand.equals("+")){ strOperation = "+"; intState = 2; } if(strCommand.equals("-")){ strOperation = "-"; intState = 2; } if(strCommand.equals("*")){ strOperation = "*"; intState = 2; } if(strCommand.equals("/")){ strOperation = "/"; intState = 2; } jtxtfieldDisplayBar.setText(strOperand1); break; } case 2:{ if(strCommand.equals("1")){ strOperand2 = "1"; intState = 3; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("2")){ strOperand2 = "2"; intState = 3; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("3")){ strOperand2 = "3"; intState = 3; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("4")){ strOperand2 = "4"; intState = 3; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("5")){ strOperand2 = "5"; intState = 3; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("6")){ strOperand2 = "6"; intState = 3; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("7")){ strOperand2 = "7"; intState = 3; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("8")){ strOperand2 = "8"; intState = 3; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("9")){ strOperand2 = "9"; intState = 3; jtxtfieldDisplayBar.setText(strOperand2); } if(blnDot){ strOperand2 = "0"; intState = 3; jtxtfieldDisplayBar.setText("0"); } break; } case 3:{ if(blnDot){ strOperand2 += "."; blnDot = false; } if(strCommand.equals("1")){ strOperand2 += "1"; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("2")){ strOperand2 += "2"; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("3")){ strOperand2 += "3"; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("4")){ strOperand2 += "4"; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("5")){ strOperand2 += "5"; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("6")){ strOperand2 += "6"; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("7")){ strOperand2 += "7"; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("8")){ strOperand2 += "8"; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("9")){ strOperand2 += "9"; jtxtfieldDisplayBar.setText(strOperand2); } if(strCommand.equals("0")){ if(Double.parseDouble(strOperand2) == 0){ } else{ strOperand2 += "0"; jtxtfieldDisplayBar.setText(strOperand2); } } if(strCommand.equals("+") || strCommand.equals("-") || strCommand.equals("*") || strCommand.equals("/")){ if(strOperation.equals("+")){ if(strOperand2 == ""){ strOperation = strCommand; } else{ double d = Double.parseDouble(strOperand1) + Double.parseDouble(strOperand2); strOperand1 = "" + d; strOperand2 = ""; strOperation = strCommand; intState = 3; jtxtfieldDisplayBar.setText(strOperand1); } } if(strOperation.equals("-")){ if(strOperand2 == ""){ strOperation = strCommand; } else{ double d = Double.parseDouble(strOperand1) - Double.parseDouble(strOperand2); strOperand1 = "" + d; strOperand2 = ""; strOperation = strCommand; intState = 3; jtxtfieldDisplayBar.setText(strOperand1); } } if(strOperation.equals("*")){ if(strOperand2 == ""){ strOperation = strCommand; } else{ double d = Double.parseDouble(strOperand1) * Double.parseDouble(strOperand2); strOperand1 = "" + d; strOperand2 = ""; strOperation = strCommand; intState = 3; jtxtfieldDisplayBar.setText(strOperand1); } } if(strOperation.equals("/")){ if(strOperand2 == ""){ strOperation = strCommand; } else{ double d = Double.parseDouble(strOperand1) / Double.parseDouble(strOperand2); strOperand1 = "" + d; strOperand2 = ""; strOperation = strCommand; intState = 3; jtxtfieldDisplayBar.setText(strOperand1); } } } if(strCommand.equals("=")){ if(strOperation.equals("+")){ double d = Double.parseDouble(strOperand1) + Double.parseDouble(strOperand2); strOperand1 = "" + d; strOperand2 = ""; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(strOperation.equals("-")){ double d = Double.parseDouble(strOperand1) - Double.parseDouble(strOperand2); strOperand1 = "" + d; strOperand2 = ""; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(strOperation.equals("*")){ double d = Double.parseDouble(strOperand1) * Double.parseDouble(strOperand2); strOperand1 = "" + d; strOperand2 = ""; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } if(strOperation.equals("/")){ if(Double.parseDouble(strOperand2) == 0){ System.err.println("Can not divid by zero."); } else{ double d = Double.parseDouble(strOperand1) / Double.parseDouble(strOperand2); strOperand1 = "" + d; strOperand2 = ""; intState = 1; jtxtfieldDisplayBar.setText(strOperand1); } } } break; } default: System.err.println("Into invalid state!"); } } } |