This is a program for generating a state table for flip flop circuits.
My problem is that the program does not get anything from the Textfield which gets the value for KAEquation, but for JAEquation, it works just fine.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;


/**
 * @author Jenielle Gabriel
 *
 */
public class FFGen extends JFrame{
	
	private String FlipflopType = "";
	private boolean isOneFlipflop = true;
	private boolean isInput = false;
	private boolean isOutput = false;
	
	String JAEquation = "";
	String KAEquation = "";
	String JBEquation = "";
	String KBEquation = "";
	String OutputEquation = "";
	
	public void First(){
		
		/**
		 * @param args
		 */
		JLabel pleaseChooseFFType;
		String[] FlipflopTypes = {"JK", "RS", "D", "T"};; 
		JComboBox FlipflopList;
		
		JLabel pleaseChooseFFNum;
		ButtonGroup FlipflopNumberGroup;
		JRadioButtonMenuItem oneFlipflop;
		JRadioButtonMenuItem twoFlipflop;
		
		JLabel pleaseCheck;
		JCheckBox oneInput;
		JCheckBox oneOutput;
		
		JButton next;
		
		JFrame first;
		JPanel firstConLeft;
		JPanel firstConRight;
	
		FlipflopList = new JComboBox(FlipflopTypes);
		FlipflopList.addActionListener(
				new ActionListener(){
					public void actionPerformed(ActionEvent e){
						JComboBox cb = (JComboBox)e.getSource();
				        FlipflopType = (String)cb.getSelectedItem();
					}
				}
		);
		
		pleaseChooseFFType = new JLabel("Type of Flipflop:");
		oneFlipflop = new JRadioButtonMenuItem ("1");
		oneFlipflop.addActionListener(
				new ActionListener(){
					public void  actionPerformed(ActionEvent e){
						isOneFlipflop = true;
					}
				}
		);
		twoFlipflop = new JRadioButtonMenuItem ("2");
		twoFlipflop.addActionListener(
				new ActionListener(){
					public void  actionPerformed(ActionEvent e){
						isOneFlipflop = false;
					}
				}
		);
		
		pleaseChooseFFNum = new JLabel("Number of Flipflops:");
		FlipflopNumberGroup = new ButtonGroup();
		FlipflopNumberGroup.add(oneFlipflop);
		FlipflopNumberGroup.add(twoFlipflop);
		
		pleaseCheck = new JLabel("There is an:");
		oneInput = new JCheckBox ("Input");
		oneInput.addItemListener(
				new ItemListener(){
					public void itemStateChanged(ItemEvent e) {
						if (e.getStateChange() == ItemEvent.SELECTED)
							isInput = true;
						else if (e.getStateChange() == ItemEvent.DESELECTED)
					    	isInput = false;
					}
				}
		);
		
		oneOutput = new JCheckBox ("Output");
		oneOutput.addItemListener(
				new ItemListener(){
					public void itemStateChanged(ItemEvent e) {
						if (e.getStateChange() == ItemEvent.SELECTED)
							isOutput = true;
						else if (e.getStateChange() == ItemEvent.DESELECTED)
					    	isOutput = false;
					}
				}
		);
		
		next = new JButton ("Next");
		next.addActionListener(
				new ActionListener(){
					public void actionPerformed(ActionEvent e){
						if(FlipflopType == "JK")
							JK();
					}
				}
		);
		
		first =  new JFrame();
		
		firstConLeft = new JPanel();
		firstConRight = new JPanel();
		firstConRight.setLayout(new GridLayout(9,1,0,0));
		firstConRight.add(pleaseChooseFFType);
		firstConRight.add(FlipflopList);
		firstConRight.add(pleaseChooseFFNum);
		firstConRight.add(oneFlipflop);
		firstConRight.add(twoFlipflop);
		firstConRight.add(pleaseCheck);
		firstConRight.add(oneInput);
		firstConRight.add(oneOutput);
		firstConRight.add(next);
		
		JPanel Empty = new JPanel();
		Empty.setLayout(new GridLayout(1,2));
		Empty.add(firstConLeft);
		Empty.add(firstConRight);
		first.add(Empty);
		
		first.setSize(250,235);
		first.setVisible(true);
		//first.validate();
	
	}
	
	public void JK(){
		
		JFrame JKFrame = new JFrame();
		
		JButton A = new JButton("A");
		JButton B = new JButton("B");
		JButton x = new JButton("x");
		JButton open = new JButton ("(");
		JButton close = new JButton (")");
		JButton and = new JButton("*");
		JButton or =  new JButton("+");
		
		final JTextField JAEq = new JTextField();
		final JTextField KAEq = new JTextField();
		final JTextField JBEq = new JTextField();
		final JTextField KBEq = new JTextField();
		final JTextField OutputEq = new JTextField();
		
		JPanel JKLeftPanel = new JPanel();
		JPanel JKRightPanel = new JPanel();
		JKRightPanel.setLayout(new GridLayout(7,2));
		JKRightPanel.add(new JLabel("Enter the equations. "));
		JKRightPanel.add(new JLabel("Observe Proper Syntax."));
		JKRightPanel.add(new JLabel("JA = "));
		JKRightPanel.add(JAEq);
	
		JKRightPanel.add(new JLabel("JB = "));
		JKRightPanel.add(JBEq);
		JKRightPanel.add(new JLabel("KA = "));
		JKRightPanel.add(KAEq);
		JKRightPanel.add(new JLabel("KB = "));
		JKRightPanel.add(KBEq);
		JKRightPanel.add(new JLabel("x = "));
		JKRightPanel.add(OutputEq);
		JKRightPanel.add(new JLabel("Generate: "));
		JButton next = new JButton("next");
		JKRightPanel.add(next);
		next.addActionListener(
				new ActionListener(){
					public void actionPerformed(ActionEvent e)
					{
						JAEquation = JAEq.getText();
						JBEquation = JAEq.getText();
						KAEquation = KAEq.getText();
						KBEquation = KAEq.getText();
						OutputEquation = OutputEq.getText();
						genarateJK();
					}
				}
		);
		
		JKFrame.add(JKRightPanel);
		JKFrame.setSize(250,235);
		JKFrame.setVisible(true);
	}
	
	public void genarateJK(){
		
		JFrame JKTableFrame = new JFrame();
		
		int c = 0;
		int nextA[] = {0,0};  //Storage for next state A (has default values)
		int nextB[]= {0,0};  //Storage for next state B (has default values)

		int JA[] = {0,0}; //Storage for JA Values
		int JB[] = {0,0}; //Storage for JB Values
		int KA[] = {0,0}; //Storage for KA Values
		int KB[] = {0,0}; //Storage for KB Values
		

		if(isOneFlipflop && !isInput){ // one flipflop, no input, no output
			String[] A = {"1","0"}; 
			c = 2;
			
			for(int j=0; j<c; j++){

				//Complement of A
				String AComp = "";
				if(A[j] == "0")
					AComp = "1";
				else
					AComp = "0";
				
				//replace JA Formula with current value of A'
				String subsJA = replace(JAEquation,"A'",AComp);
				while(!subsJA.equals(replace(JAEquation,"A'",AComp))){
					subsJA = replace(JAEquation,"A",A[j]);
				}
				
				//replace JA Formula with current value of A
				subsJA = replace(JAEquation,"A",A[j]);
				while(!subsJA.equals(replace(JAEquation,"A",A[j]))){
					subsJA = replace(JAEquation,"A",A[j]);
				}
				
				
				//replace KA Formula with current value of A'
				String subsKA = replace(KAEquation,"A'",AComp);
				while(!subsKA.equals(replace(KAEquation,"A",AComp))){
					subsKA = replace(KAEquation,"A",A[j]);
				}
				
				
				//replace KA Formula with current value of A
				 subsKA = replace(KAEquation,"A",A[j]);
				while(!subsKA.equals(replace(KAEquation,"A",A[j]))){
					subsKA = replace(KAEquation,"A",A[j]);
				}
				
				
				try{
					
				Parser parser =  new Parser();
				//compute the value of JA
				int computedJAValue = (int)parser.evaluate(subsJA);
				JA[j] = computedJAValue;
				
				//compute the value of KA
				int computedKAValue = (int)parser.evaluate(subsKA);
				KA[j] = computedKAValue;
				
				}catch(Exception e){
					//testlang.setText(e.getMessage());
				}
				
				if(JA[j] == 0 && KA[j] == 0){
					nextA[j] = Integer.parseInt(A[j]);
				}
				else  if(JA[j] == 0 && KA[j] == 1){
					nextA[j] = 0;
				}
				else  if(JA[j] == 1 && KA[j] == 0){
					nextA[j] = 1;
				}
				else  if(JA[j] == 1 && KA[j] == 1){
					if(A[j] == "0")
						nextA[j] = 1;
					else if(A[j] == "1")
						nextA[j] = 0;
				}
				
			}//End for loop
			
			
			
			
			
			JKTableFrame.setLayout(new GridLayout(1,4));
			JKTableFrame.add(new JLabel("<html>Present<br>States<br>"+A[0]+"<br>"+A[1]));
			JKTableFrame.add(new JLabel("<html>JA<br><br>"+JA[0]+"<br>"+JA[1]));
			JKTableFrame.add(new JLabel(JAEquation));
			//JKTableFrame.add(new JLabel("<html>KA<br><br>"+KA[0]+"<br>"+KA[1]));
			JKTableFrame.add(new JLabel("<html>Next<br>States<br>"+nextA[0]+"<br>"+nextA[1]));
			
		}//End one flipflop, no input, no output
		
		
		JKTableFrame.setSize(250,235);
		JKTableFrame.setVisible(true);
		
	}
	
	static String replace(String str, String pattern, String replace) {
        int s = 0;
        int e = 0;
        StringBuffer result = new StringBuffer();
    
        while ((e = str.indexOf(pattern, s)) >= 0) {
            result.append(str.substring(s, e));
            result.append(replace);
            s = e+pattern.length();
        }
        result.append(str.substring(s));
        return result.toString();
    }

	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		FFGen gui = new FFGen();
		gui.First();
		gui.repaint();
	}

}

JAEquation = JAEq.getText();
JBEquation = JAEq.getText();

Is this second line a mis-type?

(ditto for
KAEquation = KAEq.getText();
KBEquation = KAEq.getText(); )

Edited 7 Years Ago by JamesCherrill: n/a

O, yah. Thanks I fixed it already..
Now I have another problem..
Can't think of a way to for parsing XOR equations
like this:
/*XOR = & */
(A&(B&C))

This article has been dead for over six months. Start a new discussion instead.