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POEmpty String in GUI
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copied!<p>I created a java code that builds a gui. The whole program works besides the converter window I made. The error says empty string. I'm new to gui programs and I would like to know what's wrong with this program. An explanation of why too would be nice. SORRY ITS A LOT OF CODE but the program shows the error in run. It does not give a line of error. Should I start over? If so can someone give me a good starting place? In advance thank you!</p> <pre><code> package thisprogramisforfun.guiClasses; import javax.swing.*; import java.awt.FlowLayout; import java.awt.event.*; import run.listenerOp; /** * @version date * @author my name */ public class guiClassConversions extends JFrame{ private JPanel panel; private JTextField text1; private JComboBox combo1; private JComboBox combo2; private JTextField tAnswer; private final int WINDOW_WIDTH = 400; private final int WINDOW_HEIGHT = 250; private static String t1 = ""; private static String t2 = ""; private static String tA = ""; public static String over[] = {"inch", "feet", "centimeter", "second", "minute", "hour"}; public static String under[] = {"inch", "feet", "centimeter", "second", "minute", "hour"}; private static double dT1; private static double dT2; private static double dTA; private static int ic1; private static int ic2; private String cb1S0 = over[0]; private String cb1S1 = over[1]; private String cb1S2 = over[2]; private String cb1S3 = over[3]; private String cb1S4 = over[4]; private String cb1S5 = over[5]; private String cb2S0 = under[0]; private String cb2S1 = under[1]; private String cb2S2 = under[2]; private String cb2S3 = under[3]; private String cb2S4 = under[4]; private String cb2S5 = under[5]; public guiClassConversions(){ super("Coversions"); setSize(WINDOW_WIDTH, WINDOW_HEIGHT); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); buildPanel(dT1); add(panel); setVisible(true); } private void buildPanel(double dT11){ panel = new JPanel(); text1 = new JTextField(t1, 10); combo1 = new JComboBox(over); combo2 = new JComboBox(under); tAnswer = new JTextField(tA, 10); tAnswer.setEditable(false); String cb1Ans = over[ic1]; String cb2Ans = under[ic2]; listenerOp op = new listenerOp(); dT1 = Double.parseDouble(text1.getText()); tA = op.conv(cb1Ans, cb2Ans, dT1); panel.setLayout(new FlowLayout()); panel.add(text1); panel.add(combo1); panel.add(combo2); panel.add(tAnswer); combo1.addItemListener(new ItemListener(){ @Override public void itemStateChanged(ItemEvent e){ if(e.getStateChange() == ItemEvent.SELECTED){ ic1 = combo1.getSelectedIndex(); } String cb1Ans = over[ic1]; String cb2Ans = under[ic2]; listenerOp op = new listenerOp(); dT1 = Double.parseDouble(text1.getText()); tA = op.conv(cb1Ans, cb2Ans, dT1); } }); combo2.addItemListener(new ItemListener(){ @Override public void itemStateChanged(ItemEvent e){ if(e.getStateChange() == ItemEvent.SELECTED){ ic2 = combo1.getSelectedIndex(); } String cb1Ans = over[ic1]; String cb2Ans = under[ic2]; listenerOp op = new listenerOp(); dT1 = Double.parseDouble(text1.getText()); tA = op.conv(cb1Ans, cb2Ans, dT1); } }); } } </code></pre> <p>The listenerOp class is: </p> <pre><code> package run; /** * @version date * @author my name */ public class listenerOp { public String conv(String cb1, String cb2, double t1){ DanielConversions DConv = new DanielConversions(); String[] as = {"inch", "feet", "centimeter", "second", "minute", "hour"}; double dAns = 0; String sAns; while(cb1.equals(as[0])) { //while first list is inch if(cb2.equals(as[0])){ dAns = t1; }else if(cb2.equals(as[1])){ dAns = DConv.inToFeet(t1); }else if(cb2.equals(as[2])){ dAns = DConv.inToCm(t1); }else sAns = "These cannot be converted"; } while(cb1.equals(as[1])){ //while first list is feet if(cb2.equals(as[0])){ dAns = DConv.feetToInch(t1); }else if(cb2.equals(as[1])){ dAns = t1; }else if(cb2.equals(as[2])){ dAns = DConv.feetToCm(t1); }else sAns = "These cannot be converted"; } while(cb1.equals(as[2])){ //while first list is cm if(cb2.equals(as[0])){ dAns = DConv.cmToIn(t1); }else if(cb2.equals(as[1])){ dAns = DConv.cmToFeet(t1); }else if(cb2.equals(as[2])){ dAns = t1; }else sAns = "These cannot be converted"; } while(cb1.equals(as[3])){ //while first list is second if(cb2.equals(as[3])){ dAns = t1; }else if(cb2.equals(as[4])){ dAns = DConv.secondToMinute(t1); }else if(cb2.equals(as[5])){ dAns = DConv.secondToHour(t1); }else sAns = "These cannot be converted"; } while(cb1.equals(as[4])){ //while first list is minute if(cb2.equals(as[3])){ dAns = DConv.minuteToSecond(t1); }else if(cb2.equals(as[4])){ dAns = t1; }else if(cb2.equals(as[5])){ dAns = DConv.minuteToHour(t1); }else sAns = "These cannot be converted"; } while(cb1.equals(as[5])){ //while first list is hour if(cb2.equals(as[3])){ dAns = DConv.hourToSecond(t1); }else if(cb2.equals(as[4])){ dAns = DConv.hourToMinute(t1); }else if(cb2.equals(as[5])){ dAns = t1; }else sAns = "These cannot be converted"; } sAns = Double.toString(dAns); return sAns; } } </code></pre> <p>here's the main:</p> <pre><code> package thisprogramisforfun.guiClasses; import java.awt.Color; import javax.swing.*; import java.awt.event.*; import run.DanielMath; /** * @version date * @author my name */ public class guiClassMain extends JFrame{ private JPanel panel; private JLabel label; private JButton dist; private JButton interest; private JButton compInterest; private JButton largerOrSmaller; private JButton findNumber; private JButton dens; private JButton percError; private JButton conv; private static String[] buttons = {"Distance", "Interest", "Compound Interest", "Larger or Smaller", "Find Number", "Density", "Percent Error", "Conversions"}; private static String select = "Select to find "; private final int WINDOW_WIDTH = 350; private final int WINDOW_HEIGHT = 200; public guiClassMain(){ setTitle("Daniel's Homework Helper"); setSize(WINDOW_WIDTH, WINDOW_HEIGHT); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); buildPanel(); add(panel); setVisible(true); } private void buildPanel(){ panel = new JPanel(); label = new JLabel("Click on a button to perform one of the tasks: "); dist = new JButton(buttons[0]); interest = new JButton(buttons[1]); compInterest = new JButton(buttons[2]); largerOrSmaller = new JButton(buttons[3]); findNumber = new JButton(buttons[4]); dens = new JButton(buttons[5]); percError = new JButton(buttons[6]); conv = new JButton(buttons[7]); label.setForeground(Color.BLACK); panel.setBackground(Color.gray); dist.setToolTipText(select + buttons[0]); interest.setToolTipText(select + buttons[1]); compInterest.setToolTipText(select + buttons[2]); largerOrSmaller.setToolTipText(select + buttons[3]); findNumber.setToolTipText(select + buttons[4]); dens.setToolTipText(select + buttons[5]); percError.setToolTipText(select + buttons[6]); conv.setToolTipText(select + buttons[7]); panel.add(label); panel.add(dist); panel.add(interest); panel.add(compInterest); panel.add(largerOrSmaller); panel.add(findNumber); panel.add(dens); panel.add(percError); panel.add(conv); distButtonListener resp = new distButtonListener(); dist.addActionListener(resp); interestButtonListener i = new interestButtonListener(); interest.addActionListener(i); compInterestButtonListener ci = new compInterestButtonListener(); compInterest.addActionListener(ci); largerOrSmallerButtonListener ls = new largerOrSmallerButtonListener(); largerOrSmaller.addActionListener(ls); findNumbButtonListener fn = new findNumbButtonListener(); findNumber.addActionListener(fn); densButtonListener d = new densButtonListener(); dens.addActionListener(d); percErrorButtonListener pe = new percErrorButtonListener(); percError.addActionListener(pe); convButtonListener c = new convButtonListener(); conv.addActionListener(c); } private class distButtonListener implements ActionListener{ @Override public void actionPerformed(ActionEvent e){ guiClassDistance d = new guiClassDistance(); } } private class interestButtonListener implements ActionListener{ @Override public void actionPerformed(ActionEvent e){ guiClassInterest i = new guiClassInterest(); } } private class compInterestButtonListener implements ActionListener{ @Override public void actionPerformed(ActionEvent e){ guiClassCompInterest ci = new guiClassCompInterest(); } } private class largerOrSmallerButtonListener implements ActionListener{ @Override public void actionPerformed(ActionEvent e){ guiClassSmallerOrLarger sOrL = new guiClassSmallerOrLarger(); } } private class findNumbButtonListener implements ActionListener{ @Override public void actionPerformed(ActionEvent e){ guiClassFindNumber fn = new guiClassFindNumber(); } } private class densButtonListener implements ActionListener{ @Override public void actionPerformed(ActionEvent e){ guiClassDensity dens = new guiClassDensity(); } } private class percErrorButtonListener implements ActionListener{ @Override public void actionPerformed(ActionEvent e){ guiClassPercentError pe = new guiClassPercentError(); } } private class convButtonListener implements ActionListener{ @Override public void actionPerformed(ActionEvent e){ guiClassConversions c = new guiClassConversions(); } } } </code></pre> <p>In advance thank you!</p>

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