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Thread: Why does my calculator only return 0.0?

  1. #1
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    Default Why does my calculator only return 0.0?

    I am making a calculator in Java. However, when I press the "=" button on my calculator, it always returns 0.0, no matter what. I don't understand why? The code is below:

    import javax.swing.*;//import the packages needed for gui
    import java.awt.*;
    import java.awt.event.*;
    import java.util.Arrays;
    import java.util.List;
    import static java.lang.Math.*;
    public class CalculatorCopy {
        public static void main(String[] args) {
    	JFrame window = new JFrame("Window");//makes a JFrame
    	    window.setSize(300,415); 
    	window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    	JPanel panel = new JPanel (new FlowLayout());//makes the panel, textfield and buttons and gives the buttons actioncommands
        final JTextField textField = new JTextField(20);
    	JButton openbracket = new JButton("(");
    		openbracket.setActionCommand("(");
    	JButton closebracket = new JButton(")");
    	closebracket.setActionCommand(")");
    	JButton clearbutton = new JButton("C");
    	clearbutton.setActionCommand("C");
    	JButton arcsin = new JButton("arcsin");
    	arcsin.setActionCommand("arcsin");
    	JButton arccos = new JButton("arccos");
    	arccos.setActionCommand("arccos");
    	JButton arctan = new JButton("arctan");
    	arctan.setActionCommand("arctan");
    	JButton sin = new JButton("sin");
    	sin.setActionCommand("sin");
    	JButton cos = new JButton("cos");
    	cos.setActionCommand("cos");
    	JButton tan = new JButton("tan");
    	tan.setActionCommand("tan");
    	JButton log = new JButton("log");
        log.setActionCommand("log");
    	JButton seven = new JButton("7");
    	seven.setActionCommand("seven");
    	JButton eight = new JButton("8");
    	eight.setActionCommand("eight");
    	JButton nine = new JButton("9");
    	nine.setActionCommand("nine");
    	JButton four = new JButton("4");
    	four.setActionCommand("four");
    	    JButton five = new JButton("5");
    	    five.setActionCommand("five");
    	    JButton six = new JButton("6");
    	    six.setActionCommand("six");
    	    JButton one = new JButton("1");
    	    one.setActionCommand("one");
    	    JButton two = new JButton("2");
    	    two.setActionCommand("two");
    	    JButton three = new JButton("3");
    	    three.setActionCommand("three");
    	    JButton zero = new JButton("0");
    	    zero.setActionCommand("zero");
    	    JButton radixpoint = new JButton(".");
    	    radixpoint.setActionCommand("radixpoint");
    	    JButton plus = new JButton("+");
    	    plus.setActionCommand("plus");
    	    JButton subtract = new JButton("-");
    	    subtract.setActionCommand("subtract");
    	    JButton multiply = new JButton("x");
    	    multiply.setActionCommand("multiply");
    	    JButton divide = new JButton("/");
    	    divide.setActionCommand("divide");
    	    JButton equal = new JButton("=");
    	    equal.setActionCommand("equal");
    	    final String values = " ";
    	    class Listener implements ActionListener {	
    	    	String out = "";
    	     public void actionPerformed(ActionEvent e) {   		  
    		    String output = e.getActionCommand();
    		    if(output == "(") {
                   out = out + "(";
                   textField.setText(out);   
    		    } else if (output == ")") {
    		    out = out + ")";
    		    textField.setText(out);	
    		    }	else if (output == "C") {
    		    	textField.setText(" ");
    		    	out = "";
    		    }  else if (output == "arcsin") {
    		    	out = out + "asin(";
    		    	textField.setText(out);	
    		    }	else if (output == "arccos") {
    		    	out = out + "acos(";
    		    	textField.setText(out);
    		    }	 else if (output == "arctan") {
    		    	out = out + "atan(";
    		    	textField.setText(out);
    		    }   else if (output == "log") {
    		    	out = out + "log(";
    		    	textField.setText(out);	
    		    }   else if (output == "seven") {
    		    	out = out + "7";
    		    	textField.setText(out);
    		    }   else if (output == "eight") {
    		    	out = out + "8";
    		    	textField.setText(out);
    		    }   else if (output == "nine") {
    		    	out = out + "9";
    		    	textField.setText(out);
    		    }   else if (output == "four") {
    		    	out = out + "4";
    		    	textField.setText(out);
    		    }   else if (output == "five") {
    		    	out = out + "5";
    		    	textField.setText(out);
    		    }   else if (output == "six") {
    		    	out = out + "6";
    		    	textField.setText(out);
    		    }   else if (output == "one") {
    		    	out = out + "1";
    		    	textField.setText(out);
    		    }   else if (output == "two") {
    		    	out = out + "2";
    		    	textField.setText(out);
    		    }   else if (output == "three") {
    		    	out = out + "3";
    		    	textField.setText(out);
    		    }   else if (output == "zero") {
    		    	out = out + "0";
    		    	textField.setText(out);
    		    }   else if (output == "radixpoint") {
    		    	out = out + ".";
    		    	textField.setText(out);
    		    }   else if (output == "equal") {
    		    	String[] numbers = out.split("[ +-x/doublesintarclg]", 0); //separate the numbers from the operations
    		    	String[] operations = out.split("[ 1234567890.()]", 0);
    		    	double[] realnumbers = new double[100]; //make an array of doubles
    		    	double answer = 0;
    		    	for ( String number: numbers ) {
    		    	for (double realnumber : realnumbers ) {
    		    	realnumber =  Double.parseDouble(number); //make the string number a double value
    		    	}		
    		    	}	
                    for (String op : operations ) {
                    	if (op == "x") {
                    	  answer = answer + realnumbers[Arrays.asList(operations).indexOf(op)]*realnumbers[Arrays.asList(operations).indexOf(op)+1]; 
                    	}
                    	if (op == "/") {
                    	answer = answer + realnumbers[Arrays.asList(operations).indexOf(op)]/realnumbers[Arrays.asList(operations).indexOf(op)+1];
                    	}
                    	if (op == "+") {
                    	answer = answer + realnumbers[Arrays.asList(operations).indexOf(op)]+realnumbers[Arrays.asList(operations).indexOf(op)+1];	
                    	}
                    	if (op == "-") {
                    	answer = answer + realnumbers[Arrays.asList(operations).indexOf(op)]-realnumbers[Arrays.asList(operations).indexOf(op)+1];
                    	}
                    	String stringofanswer = String.valueOf(answer);
                    	textField.setText(stringofanswer);
     
                    }
    		    }   else if (output == "plus") {
    		    	out = out + "+";
    		    	textField.setText(out);
    		    }   else if (output == "subtract") {
    		    	out = out + "-";
    		    	textField.setText(out);
    		    }   else if (output == "multiply") {
    		    	out = out + "x";
    		    	textField.setText(out);
    		    }   else if (output == "divide") {
    		    	out = out + "/";
    		    	textField.setText(out);
    		    }
    		}
    	}
    	Listener listener = new Listener(); //makes an object of the actionlistener
     panel.add(textField);//adding all the things
    	    window.add(panel);
    	openbracket.addActionListener(listener);    
    	panel.add(openbracket);
    	closebracket.addActionListener(listener);
    	panel.add(closebracket);
    	clearbutton.addActionListener(listener);
    	panel.add(clearbutton);
    	arcsin.addActionListener(listener);
    	panel.add(arcsin);
    	arccos.addActionListener(listener);
    	panel.add(arccos);
    	arctan.addActionListener(listener);
    	panel.add(arctan);
    	sin.addActionListener(listener);
    	panel.add(sin);
    	cos.addActionListener(listener);
    	panel.add(cos);
    	tan.addActionListener(listener);
    	panel.add(tan);
    	log.addActionListener(listener);
    	panel.add(log);
    	nine.addActionListener(listener);
    	panel.add(nine);
    	eight.addActionListener(listener);
    	panel.add(eight);
    	seven.addActionListener(listener);
    	panel.add(seven);
    	six.addActionListener(listener);
    	panel.add(six);
    	five.addActionListener(listener);
    	panel.add(five);
    	four.addActionListener(listener);
    	panel.add(four);
    	three.addActionListener(listener);
    	panel.add(three);
    	two.addActionListener(listener);
    	panel.add(two);
    	one.addActionListener(listener);
    	panel.add(one);
    	zero.addActionListener(listener);
    	panel.add(zero);
    	radixpoint.addActionListener(listener);
    	panel.add(radixpoint);
    	plus.addActionListener(listener);
    	panel.add(plus);
    	subtract.addActionListener(listener);
    	panel.add(subtract);
    	multiply.addActionListener(listener);
    	panel.add(multiply);
    	divide.addActionListener(listener);
    	panel.add(divide);
    	equal.addActionListener(listener);
    	panel.add(equal);
    	window.setVisible(true);
    }
    }

    What's wrong with my code?


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Why does my calculator only return 0.0?

    First off, stop comparing Strings using the == operator. Use the equals() method instead. Do a search in this forum or on google for way more information on why that is.

    Secondly, what happened when you stepped through this with a debugger, or at least added some print statements, to figure out when the program's execution differs from what you expect?

    You should try creating an MCVE instead of posting your entire project. Hardcode the String input and create a method that does what the equals button should do. We don't need to see any GUI code if your only problem is converting a String into a math equation.
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