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Thread: Having a problem finding the error in my ActionListener method.

  1. #1
    Junior Member
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    Default Having a problem finding the error in my ActionListener method.

    The error for the code on my program is : error: Lesson9_Menus is not abstract and does not override abstract method actionPerformed(ActionEvent) in ActionListener

    Here's the code, thanks for the help in advance!

    import java.*;
    import java.util.Random;
    import javax.swing.*;
    import java.awt.*;
    import java.awt.event.*;
     
     public class Lesson9_Menus extends JFrame implements ActionListener{
     
    	private Container win;
     
    	JFrame f;
    	Container subWin;
     
    	JLabel inputLabel, outputLabel;
    	JTextField inputField, outputField;
    	JButton calcButton, bd_calcButton, bh_calcButton, db_calcButton, dh_calcButton, hb_calcButton, hd_calcButton;
     
    	private String binIn, hexIn;
    	private int decimal, number;
     
    	JMenuBar menubar;
    	JMenu binaryToMenu, decimalToMenu, hexToMenu;
    	JMenuItem binToDecItem, binToHexItem, decToBinItem, decToHexItem, hexToDecItem, hexToBinItem;
     
    	public Lesson9_Menus(){
    		super("Conversion from Decimal to Binary / Hexadecimal");
    		win = getContentPane();
    		win.setLayout(null);
     
    		menubar= new JMenuBar();
     
     
    		binaryToMenu = new JMenu("Binary To");
    		decimalToMenu = new JMenu("Decimal To");
    		hexToMenu = new JMenu("Hex To");
     
    		binaryToMenu.setMnemonic('B');
    		decimalToMenu.setMnemonic('B');
    		hexToMenu.setMnemonic('B');
     
    		binToDecItem = new JMenuItem("Binary to Decimal");
    		binToHexItem = new JMenuItem("Binary to Hex");
    		decToBinItem = new JMenuItem("Decimal to Binary");
    		decToHexItem = new JMenuItem("Decimal to Hex");
    		hexToDecItem = new JMenuItem("Hex to Decimal");
    		hexToBinItem = new JMenuItem("Hex to Binary");
     
    		binToDecItem.addActionListener(this);
    		binToHexItem.addActionListener(this);
    		decToBinItem.addActionListener(this);
    		decToHexItem.addActionListener(this);
    		hexToBinItem.addActionListener(this);
    		hexToDecItem.addActionListener(this);
     
    		binaryToMenu.add(binToDecItem);
    		binaryToMenu.add(binToHexItem);
     
    		decimalToMenu.add(decToBinItem);
    		decimalToMenu.add(decToHexItem);
     
    		hexToMenu.add(hexToBinItem);
    		hexToMenu.add(hexToDecItem);
     
    		menubar.add(binaryToMenu);
    		menubar.add(decimalToMenu);
    		menubar.add(hexToMenu);
     
    		setJMenuBar(menubar);
     
    		number = 0;
     
    		setSize(600,300);
    		setVisible(true);
    		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    	}
    		public static void main(String[] arg){
    			javax.swing.SwingUtilities.invokeLater(new Runnable(){
    				public void run(){
    					new Lesson9_Menus();
    				}
    			});
    		}
     
    	public void actionPerfomed(ActionEvent event){
    		if(event.getSource() ==  binToDecItem)
    			react_binToDecItem();
     
    		else if(event.getSource() ==  binToHexItem)
    			react_binToHexItem();
     
    		else if(event.getSource() ==  decToBinItem)
    			react_decToBinItem();
     
    		else if(event.getSource() ==  decToHexItem)
    			react_decToHexItem();
     
    		else if(event.getSource() ==  hexToBinItem)
    			react_hexToBinItem();
     
    		else if(event.getSource() ==  hexToDecItem)
    			react_hexToDecItem();
     
    	}
    		public void react_binToDecItem(){
    		JFrame f = new JFrame("Binary to decimal"); 
    		subWin = f.getContentPane();
    		subWin.setLayout(null);
    		subWin.setPreferredSize(new Dimension(400,200));
     
    		inputLabel = new JLabel("Enter binary number");
    		inputLabel.setSize(new Dimension(175,20));
    		inputLabel.setLocation(10,50);
    		subWin.add(inputLabel);	
     
    		inputField = new JTextField("");
    		inputField.setSize(175,20);
    		inputField.setLocation(200,50);
    		subWin.add(inputField);
     
    		outputLabel = new JLabel("Decimal Number");
    		outputLabel.setSize(new Dimension(175,20));
    		outputLabel.setLocation(10,150);
    		subWin.add(outputLabel);
     
    		outputField = new JTextField("");
    		outputField.setSize(new Dimension(175,20));
    		outputField.setLocation(200,150);
    		subWin.add(outputField);
     
    		bd_calcButton = new JButton("Calculate");
    		bd_calcButton.setSize(150,30);
    		bd_calcButton.setLocation(100,80);
    		subWin.add(bd_calcButton);
    		bd_calcButton.addActionListener(new ButtonHandler());
     
    		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		f.pack();
    		f.setVisible(true);
    		}
     
    		public void react_binToHexItem(){
    		JFrame f = new JFrame("Binary to hexadecimal"); 
    		subWin = f.getContentPane();
    		subWin.setLayout(null);
    		subWin.setPreferredSize(new Dimension(400,200));
     
    		inputLabel = new JLabel("Enter binary number");
    		inputLabel.setSize(new Dimension(175,20));
    		inputLabel.setLocation(10,50);
    		subWin.add(inputLabel);	
     
    		inputField = new JTextField("");
    		inputField.setSize(175,20);
    		inputField.setLocation(200,50);
    		subWin.add(inputField);
     
    		outputLabel = new JLabel("Hexadecimal Number");
    		outputLabel.setSize(new Dimension(175,20));
    		outputLabel.setLocation(10,150);
    		subWin.add(outputLabel);
     
    		outputField = new JTextField("");
    		outputField.setSize(new Dimension(175,20));
    		outputField.setLocation(200,150);
    		subWin.add(outputField);
     
    		bh_calcButton = new JButton("Calculate");
    		bh_calcButton.setSize(150,30);
    		bh_calcButton.setLocation(100,80);
    		subWin.add(bh_calcButton);
    		bh_calcButton.addActionListener(new ButtonHandler());
     
    		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		f.pack();
    		f.setVisible(true);
    		}
    		public void react_hexToDecItem(){
    		JFrame f = new JFrame("Hex to Decimal"); 
    		subWin = f.getContentPane();
    		subWin.setLayout(null);
    		subWin.setPreferredSize(new Dimension(400,200));
     
    		inputLabel = new JLabel("Enter hexadecimal number");
    		inputLabel.setSize(new Dimension(175,20));
    		inputLabel.setLocation(10,50);
    		subWin.add(inputLabel);	
     
    		inputField = new JTextField("");
    		inputField.setSize(175,20);
    		inputField.setLocation(200,50);
    		subWin.add(inputField);
     
    		outputLabel = new JLabel("Decimal Number");
    		outputLabel.setSize(new Dimension(175,20));
    		outputLabel.setLocation(10,150);
    		subWin.add(outputLabel);
     
    		outputField = new JTextField("");
    		outputField.setSize(new Dimension(175,20));
    		outputField.setLocation(200,150);
    		subWin.add(outputField);
     
    		hd_calcButton = new JButton("Calculate");
    		hd_calcButton.setSize(150,30);
    		hd_calcButton.setLocation(100,80);
    		subWin.add(hd_calcButton);
    		hd_calcButton.addActionListener(new ButtonHandler());
     
    		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		f.pack();
    		f.setVisible(true);
     
    		}
    		public void react_hexToBinItem(){
    		JFrame f = new JFrame("Hex to Binary"); 
    		subWin = f.getContentPane();
    		subWin.setLayout(null);
    		subWin.setPreferredSize(new Dimension(400,200));
     
    		inputLabel = new JLabel("Enter hexadecimal number");
    		inputLabel.setSize(new Dimension(175,20));
    		inputLabel.setLocation(10,50);
    		subWin.add(inputLabel);	
     
    		inputField = new JTextField("");
    		inputField.setSize(175,20);
    		inputField.setLocation(200,50);
    		subWin.add(inputField);
     
    		outputLabel = new JLabel("Binary Number");
    		outputLabel.setSize(new Dimension(175,20));
    		outputLabel.setLocation(10,150);
    		subWin.add(outputLabel);
     
    		outputField = new JTextField("");
    		outputField.setSize(new Dimension(175,20));
    		outputField.setLocation(200,150);
    		subWin.add(outputField);
     
    		hb_calcButton = new JButton("Calculate");
    		hb_calcButton.setSize(150,30);
    		hb_calcButton.setLocation(100,80);
    		subWin.add(hb_calcButton);
    		hb_calcButton.addActionListener(new ButtonHandler());
     
    		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		f.pack();
    		f.setVisible(true);
     
    		}
    		public void react_decToBinItem(){
    		JFrame f = new JFrame("Decimal to Binary"); 
    		subWin = f.getContentPane();
    		subWin.setLayout(null);
    		subWin.setPreferredSize(new Dimension(400,200));
     
    		inputLabel = new JLabel("Enter decimal number");
    		inputLabel.setSize(new Dimension(175,20));
    		inputLabel.setLocation(10,50);
    		subWin.add(inputLabel);	
     
    		inputField = new JTextField("");
    		inputField.setSize(175,20);
    		inputField.setLocation(200,50);
    		subWin.add(inputField);
     
    		outputLabel = new JLabel("Binary Number");
    		outputLabel.setSize(new Dimension(175,20));
    		outputLabel.setLocation(10,150);
    		subWin.add(outputLabel);
     
    		outputField = new JTextField("");
    		outputField.setSize(new Dimension(175,20));
    		outputField.setLocation(200,150);
    		subWin.add(outputField);
     
    		db_calcButton = new JButton("Calculate");
    		db_calcButton.setSize(150,30);
    		db_calcButton.setLocation(100,80);
    		subWin.add(db_calcButton);
    		db_calcButton.addActionListener(new ButtonHandler());
     
    		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		f.pack();
    		f.setVisible(true);
     
    		}
    		public void react_decToHexItem(){
    		JFrame f = new JFrame("Decimal to Hexadecimal"); 
    		subWin = f.getContentPane();
    		subWin.setLayout(null);
    		subWin.setPreferredSize(new Dimension(400,200));
     
    		inputLabel = new JLabel("Enter decimal number");
    		inputLabel.setSize(new Dimension(175,20));
    		inputLabel.setLocation(10,50);
    		subWin.add(inputLabel);	
     
    		inputField = new JTextField("");
    		inputField.setSize(175,20);
    		inputField.setLocation(200,50);
    		subWin.add(inputField);
     
    		outputLabel = new JLabel("Hexadecimal Number");
    		outputLabel.setSize(new Dimension(175,20));
    		outputLabel.setLocation(10,150);
    		subWin.add(outputLabel);
     
    		outputField = new JTextField("");
    		outputField.setSize(new Dimension(175,20));
    		outputField.setLocation(200,150);
    		subWin.add(outputField);
     
    		dh_calcButton = new JButton("Calculate");
    		dh_calcButton.setSize(150,30);
    		dh_calcButton.setLocation(100,80);
    		subWin.add(dh_calcButton);
    		dh_calcButton.addActionListener(new ButtonHandler());
     
    		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		f.pack();
    		f.setVisible(true);	
     
    		}
     
           private class ButtonHandler implements ActionListener{
    			public void actionPerformed(ActionEvent e){
    				if(e.getSource() == bd_calcButton){
    					String binIn = inputField.getText();
    					decimal = 0;
    					int base = 1;
    					for(int i = binIn.length() -1; i >= 0; i--){
    						char letter = binIn.charAt(i);
    						if(letter == '1'){
    							decimal += base;
    							base*= 2;
    						}
     
    					}
    					outputField.setText("" + decimal);
     
    				}
    				if(e.getSource() == bh_calcButton){
    					String binIn = inputField.getText();
    					decimal = 0;
    					int base = 1;
    					for(int i = binIn.length() - 1; i>= 0; i--){
    						char letter = binIn.charAt(i);
    						if(letter == '1'){
    							decimal += base;
    							base*=2;
    						}
    					}
    						int rem = 0;
    						String result = "";
    						for(int hexbase = 4096; hexbase >0; hexbase/=16){
    							int hexval = decimal/hexbase;
    							rem = decimal/hexbase;
    							if(hexval >=10){
     
    							switch(hexval){
    								case 10 : result += ('A'); break;
    								case 11 : result += ('B'); break;
    								case 12 : result += ('C'); break;
    								case 13 : result += ('D'); break;
    								case 14 : result += ('E'); break;
    								case 15 : result += ('F'); break;
    							}
     
    							}
    							else
    								result += hexval;
    							if(hexval >= 0)
    								decimal = rem;
     
     
    						}
    						outputField.setText(result);
    					}
    					if(e.getSource() == hd_calcButton){
    						hexIn = inputField.getText().toUpperCase();
    						decimal = 0;
    						int base = 1;
     
    						for(int i = hexIn.length() - 1; i >= 0; i--){
    							int pos = 0;
    							char letter = hexIn.charAt(i);
    							if(Character.isDigit(letter))
    								pos = letter - 48;
    							else
    								pos = letter - 55;
    							decimal += pos * base;
    							base*= 16;
    						}
    						outputField.setText("" + decimal);
    					}
    					if(e.getSource() == hb_calcButton){
    						hexIn = inputField.getText().toUpperCase();
    						int bin1;
    						decimal = 0;
    						int base = 1;
     
    						for(int i = hexIn.length() - 1; i >= 0; i--){
    							int pos = 0;
    							char letter = hexIn.charAt(i);
    							if(Character.isDigit(letter))
    								pos = letter - 48;
    							else
    								pos = letter - 55;
    							decimal += pos * base;
    							base *= 16;
     
    							}
    							int number = decimal;
    							String result = "";
     
    							for(int twobase = 128; twobase >= 0; twobase /= 2){
    								bin1 = number /twobase;
    								result += ("" + bin1);
    								if(number >= twobase)
    									number -= twobase;
    							}
     
    							outputField.setText(result);
    						}
    						if(e.getSource() == db_calcButton){
    							int number = Integer.parseInt(inputField.getText());
    							int bin1;
    							String result = "";
    							for(int twobase = 128; twobase > 0; twobase/=2){
    								bin1 = number /twobase;
    								result += ("" + bin1);
     
    								if(number >= twobase)
    									number -= twobase;
     
    							}
    							outputField.setText(result);
    						}
    						if(e.getSource() == dh_calcButton){
    							int number = Integer.parseInt(inputField.getText());
    							int rem = 0;
    							 String result = "";
    							 for(int hexbase = 4096; hexbase > 0; hexbase /= 16){
    							 	int hexval = number / hexbase;
    							 	rem = number % hexbase;
     
    							 	if(hexval >= 10){
    							 		switch(hexval){
     
    							 		case 10 : result += ('A'); break;
    									case 11 : result += ('B'); break;
    									case 12 : result += ('C'); break;
    									case 13 : result += ('D'); break;
    									case 14 : result += ('E'); break;
    									case 15 : result += ('F'); break;	
     
    									}
    							 	}
    							 	else
    							 		result += hexval;
    							 	if(hexval >= 0)
    							 		number = rem;
    							 }
    							 outputField.setText(result);
    						}
    					}
     
     
     
     
    			}		
     
     
    }

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Having a problem finding the error in my ActionListener method.

    Lesson9_Menus is not abstract and does not override abstract method actionPerformed(ActionEvent) in ActionListener
    When a class implements an interface it is required to declare all the abstract methods declared in the interface.
    The compiler can not find a definition for the method: actionPerformed(ActionEvent) in the class that implements ActionListener.

    Did you forget to code that method or should the class NOT implement ActionListener?
    If you don't understand my answer, don't ignore it, ask a question.

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