empty string error

[Kip Bodey]

I will post all of my code with a comment on the line where the issue is. but the string isnt empty to me... here is what i am trying to do. you click a number it appears in the solutionField. then hit plus, it will change the add option to true and others to false, then it will read that string in the solutionField which is the number that was clicked and set double firstNum equal to that. when i run the calculator it works fine. but this error occurs. also... it doesnt throw an error for equal, which is the same code so im a little more confused. I am only working on getting the add function to work without error right now, which is why everything else looks blah, thank you

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;


public class CalculatorView extends JFrame{
	
	CalculatorModel call = new CalculatorModel();
	
	Double firstNum;
	Double secondNum;
	
	private JButton one;
	private JButton two;
	private JButton three;
	private JButton four;
	private JButton five;
	private JButton six;
	private JButton seven;
	private JButton eight;
	private JButton nine;
	private JButton zero;
	private JButton decimal;
	private JButton plus;
	private JButton minus;
	private JButton times;
	private JButton divide;
	private JButton equals;
	private JButton clear;
	private JTextField solutionField;
	private boolean addOpt;
	
	
	public CalculatorView(){
		
		// Sets up the view and adds the components
		
		setTitle("Calculator");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setLocationRelativeTo(null);
		
		setSize(300, 300);
		
		setLayout(new BorderLayout());
		
		JPanel buttonPanel = new JPanel();
		
		add(buttonPanel, BorderLayout.CENTER);
		buttonPanel.setLayout(new GridLayout(4, 4, 8, 8));
		
		solutionField = new JTextField();// this is where the answer will go
		add(solutionField, BorderLayout.NORTH);
		solutionField.setEditable(false);

		
		equals = new JButton("=");
		add(equals, BorderLayout.SOUTH);
		

		
		
		one = new JButton("1");
		two = new JButton("2");
		three = new JButton("3");
		plus = new JButton("+");
		four = new JButton("4");
		five = new JButton("5");
		six = new JButton("6");
		minus = new JButton("-");
		seven = new JButton("7");
		eight = new JButton("8");
		nine = new JButton("9");
		times = new JButton("*");
		zero = new JButton("0");
		decimal = new JButton(".");
		clear = new JButton("C");
		divide = new JButton("/");
		buttonPanel.add(one);
		buttonPanel.add(two);
		buttonPanel.add(three);
		buttonPanel.add(plus);
		buttonPanel.add(four);
		buttonPanel.add(five);
		buttonPanel.add(six);
		buttonPanel.add(minus);
		buttonPanel.add(seven);
		buttonPanel.add(eight);
		buttonPanel.add(nine);
		buttonPanel.add(times);
		buttonPanel.add(zero);
		buttonPanel.add(decimal);
		buttonPanel.add(clear);
		buttonPanel.add(divide);
		

		setVisible(true);
		
		theHandler handler = new theHandler();
		one.addActionListener(handler);
		two.addActionListener(handler);
		three.addActionListener(handler);
		four.addActionListener(handler);
		five.addActionListener(handler);
		six.addActionListener(handler);
		seven.addActionListener(handler);
		eight.addActionListener(handler);
		nine.addActionListener(handler);
		zero.addActionListener(handler);
		plus.addActionListener(handler);
		decimal.addActionListener(handler);
		plus.addActionListener(handler);
		minus.addActionListener(handler);
		times.addActionListener(handler);
		divide.addActionListener(handler);
		equals.addActionListener(handler);
		plus.addActionListener(handler);
		clear.addActionListener(handler);
	}
	
	
	private class theHandler implements ActionListener{
		public void actionPerformed(ActionEvent event){
			if(event.getSource()==one){
				solutionField.setText(solutionField.getText() + Integer.toString(1));
			}
			if(event.getSource()==two){
				solutionField.setText(solutionField.getText() + Integer.toString(2));
			}
			if(event.getSource()==three){
				solutionField.setText(solutionField.getText() + Integer.toString(3));
			}
			if(event.getSource()==four){
				solutionField.setText(solutionField.getText() + Integer.toString(4));
			}
			if(event.getSource()==five){
				solutionField.setText(solutionField.getText() + Integer.toString(5));
			}
			if(event.getSource()==six){
				solutionField.setText(solutionField.getText() + Integer.toString(6));
			}
			if(event.getSource()==seven){
				solutionField.setText(solutionField.getText() + Integer.toString(7));
			}
			if(event.getSource()==eight){
				solutionField.setText(solutionField.getText() + Integer.toString(8));
			}
			if(event.getSource()==nine){
				solutionField.setText(solutionField.getText() + Integer.toString(9));
			}
			if(event.getSource()==zero){
				solutionField.setText(solutionField.getText() + Integer.toString(0));
			}
			if(event.getSource()==clear){
				solutionField.setText(null);
			}
			
			
			
			if(event.getSource()==plus){
				addOpt = true;
				firstNum = Double.parseDouble(solutionField.getText()); // This is where the error is occurring
				solutionField.setText(null);
				
			}
			if(event.getSource()==equals){
				if(addOpt == true){
					secondNum = Double.parseDouble(solutionField.getText());
					solutionField.setText(Double.toString(call.addNumbers(firstNum, secondNum)));
				}
			}	
		}
	}	 
}

public class CalculatorModel {
	  
		private Double total;

		public Double addNumbers(Double a, Double b){

	       return total = a + b;
	    }
/*
	    public void subtractNumbers(int a, int b){

	        total = a - b;
	    }

	    public void multiplyNumbers(int a, int b){

	        total = a * b;
	    }

	    public void divideNumbers(int a, int b){

	        total = a / b;
	    }
	    
	    public int getTotal(){
	        return total;
	    }
*/	    
	    
}

public class MVCCalculator {

	public static void main(String[] args) {
		 new CalculatorView();

	}

}

by the way this is the error message
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
at sun.misc.FloatingDecimal.parseDouble(Unknown Source)
at java.lang.Double.parseDouble(Unknown Source)
at CalculatorView$theHandler.actionPerformed(CalculatorView.java:165)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$400(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

[Paul Clapham]

You'll definitely want to check that the solutionField component actually contains something before you call Double.parseDouble() on it. There's nothing in your code that prevents that from happening, as far as I can see.

[Kip Bodey]

okay, I will take care of that at some point thanks, but that still isnt fixing my current problem

[Paul Clapham]

Your current problem is that you're taking the contents of the solutionField, which are an empty string, and calling Double.parseDouble on that value without checking that it's not blank. Alternatively you could avoid doing the check, but then you should catch the exception and deal with it appropriately when the user clicks the + button and the field is empty.

[Kip Bodey]

okay, but the field is not empty thats what i am not getting, i understand if i didnt click a button. but lets say i click a number and it is up in the field, then i hit plus it reads in the text field which has a 5 in it, it says empty string? i finished the program for everything, and everything works the way it should but the plus sign still throws that error. everything only works fine if i do everything correct i know i need to fix that still. but assume i pushed the button i am not understanding

[Janeice DelVecchio]

If you do a system.out.println(solutionField.getText()) at the line before the error, what's the value? Is it null? Empty? Something that's not all numbers?

[Kip Bodey]

it prints the value that was in the box, then throws the error? here ill show you my new code, everything works, but that, i mean it still works, it just throws error

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;


public class CalculatorView extends JFrame{
	
	CalculatorModel call = new CalculatorModel();
	
	Double firstNum;
	Double secondNum;
	
	String first;
	String second;
	
	private JButton one;
	private JButton two;
	private JButton three;
	private JButton four;
	private JButton five;
	private JButton six;
	private JButton seven;
	private JButton eight;
	private JButton nine;
	private JButton zero;
	private JButton decimal;
	private JButton plus;
	private JButton minus;
	private JButton times;
	private JButton divide;
	private JButton equals;
	private JButton clear;
	private JTextField solutionField;
	private boolean addOpt;
	private boolean subtractOpt;
	private boolean multiplyOpt;
	private boolean divideOpt;
	
	
	public CalculatorView(){
		
		// Sets up the view and adds the components
		
		setTitle("Calculator");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setLocationRelativeTo(null);
		
		setSize(300, 300);
		
		setLayout(new BorderLayout());
		
		JPanel buttonPanel = new JPanel();
		
		add(buttonPanel, BorderLayout.CENTER);
		buttonPanel.setLayout(new GridLayout(4, 4, 8, 8));
		
		solutionField = new JTextField();// this is where the answer will go
		add(solutionField, BorderLayout.NORTH);
		solutionField.setEditable(false);
		
		Font font1 = new Font("Monospaced", Font.BOLD, 20); //this creates the font
		solutionField.setFont(font1); // this sets the font

		
		equals = new JButton("=");
		add(equals, BorderLayout.SOUTH);
		

		
		
		one = new JButton("1");
		two = new JButton("2");
		three = new JButton("3");
		plus = new JButton("+");
		four = new JButton("4");
		five = new JButton("5");
		six = new JButton("6");
		minus = new JButton("-");
		seven = new JButton("7");
		eight = new JButton("8");
		nine = new JButton("9");
		times = new JButton("*");
		zero = new JButton("0");
		decimal = new JButton(".");
		clear = new JButton("C");
		divide = new JButton("/");
		buttonPanel.add(one);
		buttonPanel.add(two);
		buttonPanel.add(three);
		buttonPanel.add(plus);
		buttonPanel.add(four);
		buttonPanel.add(five);
		buttonPanel.add(six);
		buttonPanel.add(minus);
		buttonPanel.add(seven);
		buttonPanel.add(eight);
		buttonPanel.add(nine);
		buttonPanel.add(times);
		buttonPanel.add(zero);
		buttonPanel.add(decimal);
		buttonPanel.add(clear);
		buttonPanel.add(divide);
		

		setVisible(true);
		
		theHandler handler = new theHandler();
		one.addActionListener(handler);
		two.addActionListener(handler);
		three.addActionListener(handler);
		four.addActionListener(handler);
		five.addActionListener(handler);
		six.addActionListener(handler);
		seven.addActionListener(handler);
		eight.addActionListener(handler);
		nine.addActionListener(handler);
		zero.addActionListener(handler);
		plus.addActionListener(handler);
		decimal.addActionListener(handler);
		plus.addActionListener(handler);
		minus.addActionListener(handler);
		times.addActionListener(handler);
		divide.addActionListener(handler);
		equals.addActionListener(handler);
		plus.addActionListener(handler);
		clear.addActionListener(handler);
	}
	
	
	private class theHandler implements ActionListener{
		public void actionPerformed(ActionEvent event){
			if(event.getSource()==one){
				solutionField.setText(solutionField.getText() + Integer.toString(1));
			}
			if(event.getSource()==two){
				solutionField.setText(solutionField.getText() + Integer.toString(2));
			}
			if(event.getSource()==three){
				solutionField.setText(solutionField.getText() + Integer.toString(3));
			}
			if(event.getSource()==four){
				solutionField.setText(solutionField.getText() + Integer.toString(4));
			}
			if(event.getSource()==five){
				solutionField.setText(solutionField.getText() + Integer.toString(5));
			}
			if(event.getSource()==six){
				solutionField.setText(solutionField.getText() + Integer.toString(6));
			}
			if(event.getSource()==seven){
				solutionField.setText(solutionField.getText() + Integer.toString(7));
			}
			if(event.getSource()==eight){
				solutionField.setText(solutionField.getText() + Integer.toString(8));
			}
			if(event.getSource()==nine){
				solutionField.setText(solutionField.getText() + Integer.toString(9));
			}
			if(event.getSource()==zero){
				solutionField.setText(solutionField.getText() + Integer.toString(0));
			}
			if(event.getSource()==clear){
				solutionField.setText(null);
			}
			if(event.getSource()==decimal){
				solutionField.setText(solutionField.getText() + ".");
			}
			
			
			
			if(event.getSource()==plus){
				addOpt = true;
				subtractOpt = false;
				multiplyOpt = false;
				divideOpt = false;
				System.out.println(solutionField.getText());
				firstNum = Double.parseDouble(solutionField.getText()); // This is where the error is occurring
				solutionField.setText(null);	
			}
			
			if(event.getSource()==minus){
				addOpt = false;
				subtractOpt = true;
				multiplyOpt = false;
				divideOpt = false;
				
				firstNum = Double.parseDouble(solutionField.getText()); 
				solutionField.setText(null);
			}
			
			if(event.getSource()==times){
				addOpt = false;
				subtractOpt = false;
				multiplyOpt = true;
				divideOpt = false;
				firstNum = Double.parseDouble(solutionField.getText()); 
				solutionField.setText(null);
			}
			
			if(event.getSource()==divide){
				addOpt = false;
				subtractOpt = false;
				multiplyOpt = false;
				divideOpt = true;
				firstNum = Double.parseDouble(solutionField.getText()); 
				solutionField.setText(null);
			}
			
			if(event.getSource()==equals){
				if(addOpt == true){
					secondNum = Double.parseDouble(solutionField.getText());
					call.addNumbers(firstNum, secondNum);
					solutionField.setText(Double.toString(call.getTotal()));
					//solutionField.setText(Double.toString(call.addNumbers(firstNum, secondNum)));
				}	
				else if(subtractOpt == true){
					secondNum = Double.parseDouble(solutionField.getText());
					call.subtractNumbers(firstNum, secondNum);
					solutionField.setText(Double.toString(call.getTotal()));
				}	
				else if(multiplyOpt == true){
					secondNum = Double.parseDouble(solutionField.getText());
					call.multiplyNumbers(firstNum, secondNum);
					solutionField.setText(Double.toString(call.getTotal()));
				}
				else if(divideOpt == true){
					secondNum = Double.parseDouble(solutionField.getText());
					if(secondNum==0){
						solutionField.setText("0");
					}else{
						call.divideNumbers(firstNum, secondNum);
						solutionField.setText(Double.toString(call.getTotal()));
					}
				}
			}	
		}
	}
}

[Janeice DelVecchio]

If you use a decimal point does it still throw the error?

[Kip Bodey]

Yeah it does

[Paul Clapham]

I tried to run your code, but I can't because it isn't an SSCCE (follow that link). I tried deleting all the references to the CalculatorModel class but that didn't help because there's no public static void main(String[] args) method. So I'm stuck, sorry.

[Kip Bodey]

Well there are two other parts thats why it wouldnt run, here is the rest of the code

public class CalculatorModel {
	  
		private double total;

		
		
	public double addNumbers(double a, double b){

	      return  total = a + b;
	    }

	    public double subtractNumbers(double a, double b){

	      return  total = a - b;
	    }

	    public void multiplyNumbers(double a, double b){

	        total = a * b;
	    }

	    public void divideNumbers(double a, double b){

	        total = a / b;
	    }
	    
	    public double getTotal(){
	        return total;
	    }
	    
	    
}

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;


public class CalculatorView extends JFrame{
	
	CalculatorModel call = new CalculatorModel();
	
	Double firstNum;
	Double secondNum;
	
	String first;
	String second;
	
	private JButton one;
	private JButton two;
	private JButton three;
	private JButton four;
	private JButton five;
	private JButton six;
	private JButton seven;
	private JButton eight;
	private JButton nine;
	private JButton zero;
	private JButton decimal;
	private JButton plus;
	private JButton minus;
	private JButton times;
	private JButton divide;
	private JButton equals;
	private JButton clear;
	private JTextField solutionField;
	private boolean addOpt;
	private boolean subtractOpt;
	private boolean multiplyOpt;
	private boolean divideOpt;
	
	
	public CalculatorView(){
		
		// Sets up the view and adds the components
		
		setTitle("Calculator");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setLocationRelativeTo(null);
		
		setSize(300, 300);
		
		setLayout(new BorderLayout());
		
		JPanel buttonPanel = new JPanel();
		
		add(buttonPanel, BorderLayout.CENTER);
		buttonPanel.setLayout(new GridLayout(4, 4, 8, 8));
		
		solutionField = new JTextField();// this is where the answer will go
		add(solutionField, BorderLayout.NORTH);
		solutionField.setEditable(false);
		
		Font font1 = new Font("Monospaced", Font.BOLD, 20); //this creates the font
		solutionField.setFont(font1); // this sets the font
		solutionField.setText("0.0");
		
		equals = new JButton("=");
		add(equals, BorderLayout.SOUTH);
		

		
		
		one = new JButton("1");
		two = new JButton("2");
		three = new JButton("3");
		plus = new JButton("+");
		four = new JButton("4");
		five = new JButton("5");
		six = new JButton("6");
		minus = new JButton("-");
		seven = new JButton("7");
		eight = new JButton("8");
		nine = new JButton("9");
		times = new JButton("*");
		zero = new JButton("0");
		decimal = new JButton(".");
		clear = new JButton("C");
		divide = new JButton("/");
		buttonPanel.add(one);
		buttonPanel.add(two);
		buttonPanel.add(three);
		buttonPanel.add(plus);
		buttonPanel.add(four);
		buttonPanel.add(five);
		buttonPanel.add(six);
		buttonPanel.add(minus);
		buttonPanel.add(seven);
		buttonPanel.add(eight);
		buttonPanel.add(nine);
		buttonPanel.add(times);
		buttonPanel.add(zero);
		buttonPanel.add(decimal);
		buttonPanel.add(clear);
		buttonPanel.add(divide);
		

		setVisible(true);
		
		theHandler handler = new theHandler();
		one.addActionListener(handler);
		two.addActionListener(handler);
		three.addActionListener(handler);
		four.addActionListener(handler);
		five.addActionListener(handler);
		six.addActionListener(handler);
		seven.addActionListener(handler);
		eight.addActionListener(handler);
		nine.addActionListener(handler);
		zero.addActionListener(handler);
		plus.addActionListener(handler);
		decimal.addActionListener(handler);
		plus.addActionListener(handler);
		minus.addActionListener(handler);
		times.addActionListener(handler);
		divide.addActionListener(handler);
		equals.addActionListener(handler);
		plus.addActionListener(handler);
		clear.addActionListener(handler);
	}
	
	
	private class theHandler implements ActionListener{
		public void actionPerformed(ActionEvent event){
			if(event.getSource()==one){
				solutionField.setText(solutionField.getText() + Integer.toString(1));
			}
			if(event.getSource()==two){
				solutionField.setText(solutionField.getText() + Integer.toString(2));
			}
			if(event.getSource()==three){
				solutionField.setText(solutionField.getText() + Integer.toString(3));
			}
			if(event.getSource()==four){
				solutionField.setText(solutionField.getText() + Integer.toString(4));
			}
			if(event.getSource()==five){
				solutionField.setText(solutionField.getText() + Integer.toString(5));
			}
			if(event.getSource()==six){
				solutionField.setText(solutionField.getText() + Integer.toString(6));
			}
			if(event.getSource()==seven){
				solutionField.setText(solutionField.getText() + Integer.toString(7));
			}
			if(event.getSource()==eight){
				solutionField.setText(solutionField.getText() + Integer.toString(8));
			}
			if(event.getSource()==nine){
				solutionField.setText(solutionField.getText() + Integer.toString(9));
			}
			if(event.getSource()==zero){
				solutionField.setText(solutionField.getText() + Integer.toString(0));
			}
			if(event.getSource()==clear){
				solutionField.setText(null);
			}
			if(event.getSource()==decimal){
				solutionField.setText(solutionField.getText() + ".");
			}
			
			
			
			if(event.getSource()==plus){
				addOpt = true;
				subtractOpt = false;
				multiplyOpt = false;
				divideOpt = false;
				System.out.println(solutionField.getText());
				firstNum = Double.parseDouble(solutionField.getText()); // This is where the error is occurring
				solutionField.setText(null);	
			}
			
			if(event.getSource()==minus){
				addOpt = false;
				subtractOpt = true;
				multiplyOpt = false;
				divideOpt = false;
				
				firstNum = Double.parseDouble(solutionField.getText()); 
				solutionField.setText(null);
			}
			
			if(event.getSource()==times){
				addOpt = false;
				subtractOpt = false;
				multiplyOpt = true;
				divideOpt = false;
				firstNum = Double.parseDouble(solutionField.getText()); 
				solutionField.setText(null);
			}
			
			if(event.getSource()==divide){
				addOpt = false;
				subtractOpt = false;
				multiplyOpt = false;
				divideOpt = true;
				firstNum = Double.parseDouble(solutionField.getText()); 
				solutionField.setText(null);
			}
			
			if(event.getSource()==equals){
				if(addOpt == true){
					secondNum = Double.parseDouble(solutionField.getText());
					call.addNumbers(firstNum, secondNum);
					solutionField.setText(Double.toString(call.getTotal()));
					//solutionField.setText(Double.toString(call.addNumbers(firstNum, secondNum)));
				}	
				else if(subtractOpt == true){
					secondNum = Double.parseDouble(solutionField.getText());
					call.subtractNumbers(firstNum, secondNum);
					solutionField.setText(Double.toString(call.getTotal()));
				}	
				else if(multiplyOpt == true){
					secondNum = Double.parseDouble(solutionField.getText());
					call.multiplyNumbers(firstNum, secondNum);
					solutionField.setText(Double.toString(call.getTotal()));
				}
				else if(divideOpt == true){
					secondNum = Double.parseDouble(solutionField.getText());
					if(secondNum==0){
						solutionField.setText("0");
					}else{
						call.divideNumbers(firstNum, secondNum);
						solutionField.setText(Double.toString(call.getTotal()));
					}
				}
			}	
		}
	}
}

public class MVCCalculator {

	public static void main(String[] args) {
		 new CalculatorView();

	}

}

[fred rosenberger]

Kip Bodey wrote:Well there are two other parts thats why it wouldnt run, here is the rest of the code

Did you read the SSCCE link Paul posted above?

[Kip Bodey]

yes i did, i can trim it to where the error occurs, but im just as concerned with why it isnt happening for the other operand buttons, they have the exact same code copied and pasted

if(event.getSource()==plus){
				addOpt = true;
				subtractOpt = false;
				multiplyOpt = false;
				divideOpt = false;
				firstNum = Double.parseDouble(solutionField.getText()); // This is where the error is occurring
				solutionField.setText(null);	
			}
			
			if(event.getSource()==minus){
				addOpt = false;
				subtractOpt = true;
				multiplyOpt = false;
				divideOpt = false;
				firstNum = Double.parseDouble(solutionField.getText()); 
				solutionField.setText(null);
			}

now only one throws an error, but they do the exact same thing?

[Paul Clapham]

It would help if you could produce an SSCCE so that other people can run your code. (Hint: what does the first "S" in that acronym stand for?)

[Kip Bodey]

it stands for short, so i made short code for just the plus sign and three numbers and it works, which again will not solve my problem, there id something small in my entire code that is wrong i think and i cant find it here is the code for it to work

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;


public class CalculatorView extends JFrame{


	CalculatorModel call = new CalculatorModel();
	
	Double firstNum;
	Double secondNum;
	private JButton one;
	private JButton two;
	private JButton three;
	private JButton equals;
	private JButton clear;
	private JTextField solutionField;
	private JButton plus;
	
public CalculatorView(){
		
		// Sets up the view and adds the components
		
		setTitle("Calculator");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setLocationRelativeTo(null);
		
		setSize(300, 300);
		
		setLayout(new BorderLayout());
		
		JPanel buttonPanel = new JPanel();
		
		add(buttonPanel, BorderLayout.CENTER);
		buttonPanel.setLayout(new GridLayout(4, 4, 8, 8));
		
		solutionField = new JTextField();// this is where the answer will go
		add(solutionField, BorderLayout.NORTH);
		solutionField.setEditable(false);
		
		Font font1 = new Font("Monospaced", Font.BOLD, 20); //this creates the font
		solutionField.setFont(font1); // this sets the font
		solutionField.setText("");
		
		equals = new JButton("=");
		add(equals, BorderLayout.SOUTH);

		one = new JButton("1");
		two = new JButton("2");
		three = new JButton("3");
		plus = new JButton("+");
		clear = new JButton("C");
		
		buttonPanel.add(one);
		buttonPanel.add(two);
		buttonPanel.add(three);
		buttonPanel.add(plus);
		buttonPanel.add(clear);
		
		setVisible(true);
		
		theHandler handler = new theHandler();
		one.addActionListener(handler);
		two.addActionListener(handler);
		three.addActionListener(handler);
		plus.addActionListener(handler);
		equals.addActionListener(handler);
		clear.addActionListener(handler);
}

private class theHandler implements ActionListener{
	public void actionPerformed(ActionEvent event){
		if(event.getSource()==one){
			solutionField.setText(solutionField.getText() + Integer.toString(1));
		}
		if(event.getSource()==two){
			solutionField.setText(solutionField.getText() + Integer.toString(2));
		}
		if(event.getSource()==three){
			solutionField.setText(solutionField.getText() + Integer.toString(3));
		}
		if(event.getSource()==clear){
			solutionField.setText(null);
		}
		if(event.getSource()==plus){
			firstNum = Double.parseDouble(solutionField.getText()); // This is where the error is occurring
			solutionField.setText(null);	
		}
		if(event.getSource()==equals){
				secondNum = Double.parseDouble(solutionField.getText());
				call.addNumbers(firstNum, secondNum);
				solutionField.setText(Double.toString(call.getTotal()));
				//solutionField.setText(Double.toString(call.addNumbers(firstNum, secondNum)));
			}
	}
}
	public static void main(String[] args) {
		 new CalculatorView();

	}


}

public class CalculatorModel {
	  
		private double total;

		
		
	public double addNumbers(double a, double b){

	      return  total = a + b;
	    }
	 public double getTotal(){
	        return total;
	    }
	    

}

[Kip Bodey]

i put in an event handler for the plus button twice, thats what was causing the issue. but thanks for the help, and for the advice on how to ask for help in the future!!

[Paul Clapham]

Right, I can see how that would cause the problem. And your last bit of posted code is much better for an SSCCE -- it's hard to make Swing code short but it's always worth removing near-duplicate code, like what you did.