Thread: why does the clear sign not work on my calculator?

here is the code I wrote:

import javax.swing.*;
 
import java.awt.MenuBar;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
public class NewCalculator implements ActionListener {
 
	//assign button clicked number and answer onto variables.
	int numone=0,numtwo=0, answer=0;
	char operator=' ';
	//components of calculator
	JButton one = new JButton("1");
	JButton two = new JButton("2");
	JButton three = new JButton("3");
	JButton four = new JButton("4");
	JButton five = new JButton("5");
	JButton six= new JButton("6");
	JButton seven = new JButton("7");
	JButton eight= new JButton("8");
	JButton nine = new JButton("9");
	JButton zero = new JButton("0");
	JButton C= new JButton("C");
	JButton CE = new JButton("CE");
	JButton plus = new JButton("+");
	JButton minus= new JButton("-");
	JButton multiply = new JButton("*");
	JButton divide = new JButton("/");
	JButton sqrt = new JButton("sqrt");
	JButton percent = new JButton("%");
	JButton equal = new JButton("=");
	JButton x = new JButton("1/x");
	JButton plusmin = new JButton("+/-");
	JButton fullstop = new JButton(".");
	JButton backsp = new JButton("backspace");
	JTextField textfl=new JTextField();
	JMenuBar menu = new JMenuBar();
	//used to implement panels for calculator layout.
 
	JPanel NewCalculator(){
 
		//action listener to listen to event on these contents.
		 one.addActionListener(this);
		 two.addActionListener(this);
		 three.addActionListener(this);
		 four.addActionListener(this);
		 five.addActionListener(this);
		 six.addActionListener(this);
		 seven.addActionListener(this);
		 eight.addActionListener(this);
		 nine.addActionListener(this);
		 zero.addActionListener(this);
		 plus.addActionListener(this);
		 minus.addActionListener(this);
		 multiply.addActionListener(this);
		 divide.addActionListener(this);
		 sqrt.addActionListener(this);
		 percent.addActionListener(this);
		 equal.addActionListener(this);
		 x.addActionListener(this);
		 plusmin.addActionListener(this);
		 fullstop.addActionListener(this);
		 backsp.addActionListener(this);
		 textfl.addActionListener(this);
 
		 //main panel
		JPanel parent = new JPanel();
		//manually modify panels
		 parent.setLayout(null);
		//panel for number buttons
		JPanel numbers = new JPanel();
		numbers.setSize(150,150);
		numbers.setLocation(10,70);
		numbers.add(one);
		numbers.add(two);
		numbers.add(three);
		numbers.add(four);
		numbers.add(five);
		numbers.add(six);
		numbers.add(seven);
		numbers.add(eight);
		numbers.add(nine);
		numbers.add(zero);
		numbers.add(equal);
		numbers.add(zero);
		numbers.add(fullstop);
		numbers.add(plusmin);
		//add content to main parent panel
		parent.add(numbers);
 
		//panel for math button
		JPanel math = new JPanel();
		math.setSize(100,190);
		math.setLocation(160,50);
		math.add(C);
		math.add(CE);
		math.add(plus);
		math.add(minus);
		math.add(multiply);
		math.add(divide);
		math.add(equal);
		math.add(sqrt);
		math.add(percent);
		//add content to main parent panel
		parent.add(math);
 
		//calling new backspace button to position it separately on the parent panel
		backsp=new JButton("Backspace");
		backsp.setSize(120,20);
		backsp.setLocation(20,50);
		parent.add(backsp);
 
 
		//calling new text field to position it separately on the parent panel
		textfl=new JTextField(); 
		textfl.setSize(200,20);
		textfl.setLocation(20,20);
		//add content to main parent panel
		parent.add(textfl);
 
 
		//calling menu separately to position it on the parent panel
		menu = new JMenuBar();
		menu.setSize(370,20);
		menu.setLocation(0,0);
		JMenu help = new JMenu("help");
		JMenu about = new JMenu("about");
		menu.add(help);
		menu.add(about);
		//add content to main parent panel
		parent.add(menu);
 
		//returns the main parent panel with all the sub panels and contents
		return parent;
	}
 
	//creating frame separately
	private static void frameCreation(){
 
		JFrame title = new JFrame("calculator");
 
		NewCalculator calcul = new NewCalculator();
 
		title.setContentPane(calcul.NewCalculator());
 
		title.setSize(370, 320);
		title.setVisible(true);
	}
 
 
public static void main(String[] args){
	//Schedule a job for the event-dispatching thread:
    //creating and showing this application's GUI.
	 SwingUtilities.invokeLater(new Runnable() {
         public void run() {
             frameCreation();
         }
     });
 
 
 
	//end of main
}
 
 
	@Override
	public void actionPerformed(ActionEvent e) {
		// TODO Auto-generated method stub
	//identifies the actions of each separate components even if all the component actions 
	//are the same
		String action = e.getActionCommand();
 
		if(action.equals("=")){
		//gets the text in text filed and convert it to integer value to be used to calculate.
			numtwo=Integer.parseInt(textfl.getText());
 
			//deletes the old text displayed on the text filed to display the answer (eclipse).
			textfl.setText("");
			Answer();
			DisplayResults();
 
		}
 
		//if the C button is clicked
		else if(action.equals("C")){
			//clears the text on the text field.
			textfl.setText("");
		}
		else if(action.equals("CE")){
			//clears the text on the text field.
			textfl.setText("");
		}
 
		else if(action.equals("+")){
			operator='+';
			numone=Integer.parseInt(textfl.getText());
			operator=e.getActionCommand().charAt(0);
			textfl.setText("");
 
		}
		else if(action.equals("-")){
			operator='-';
			numone=Integer.parseInt(textfl.getText());
			operator=e.getActionCommand().charAt(0);
			textfl.setText("");
 
		}
		else if(action.equals("*")){
			operator='*';
			numone=Integer.parseInt(textfl.getText());
			operator=e.getActionCommand().charAt(0);
			textfl.setText("");
 
		}
		else if(action.equals("/")){
			operator='/';
			numone=Integer.parseInt(textfl.getText());
			operator=e.getActionCommand().charAt(0);
			textfl.setText("");
 
		}
		else if(action.equals("%")){
			operator='/';
			numone=Integer.parseInt(textfl.getText());
			operator=e.getActionCommand().charAt(0);
			textfl.setText("");
 
		}
		else
		{
 
		textfl.setText(textfl.getText()+action);	
 
		}
 
	//actionPerformed end	
	}
 
//if one of the math buttons are clicked then one of the mathematical calculation will be 
	//calculated.
	public void Answer(){
 
		switch(operator)
		{
		case '+':
			answer=numone+numtwo;
		break;
 
		case '-':
		answer=numone-numtwo;
		break;
 
		case '*':
			answer=numone*numtwo;
		return;
 
		case '/':
		//if user attempts to divide by 0, then an error message is displayed.
		if(numtwo==0){
 
			textfl.setText("cannot divide by 0");
			textfl.setText("");
			}
			else{
			//calculates answer
			answer=numone/numtwo;
			}
		break;
		default:
			answer=0;
		}
 
		}
 
		//displays the answer.
		public void DisplayResults(){
 
			textfl.setText(String.valueOf(answer));
		}
 
 
	}
//public class end

Also what is the code I need to use to do the percentage and square root calculation in the calculation. Cos I am not sure about the sign I am required to use to do the calculation.

thanks in advance.

--- Update ---

the if statement is where the code to make the clear button (C and CE) work.

thanks. but how do I do square root and percentage maths on this?