Help with negative numbers

I'm writing a calculator in Java and I am having trouble with negative numbers. The numbers are stored in and array of strings, called input, and Output is a text field where I display my results. Temp is a double. When I run the program and enter a negative number, it acts as if it is positive. I convert a string to a double, multiply by -1, and convert back to a string to display. What is wrong? Here is the relevant code:
{
temp = Double.parseDouble(input[2]);
temp = -1 * temp;
Output.setText(temp.toString());
}

P.S. Is there a special way to format code? If so, what is it?

I'm not sure what your actual problem is. This seems to work fine for me:

Code:

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public class Test{
        public static void main(String[] args){
                String stringD = "-1";
                double doubleD = Double.parseDouble(stringD);
                System.out.println(doubleD);
        }
}

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PS- Quote my message to see code tags in action.

I fixed it. It turns out that while I updated the display, I didn't store the new value in my input array. I have another class which takes the input and finds the result, but it never got the new value. That was stupid of me.

Code:

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public class Main
  public static void main(String args[])  {
    System.out.println("Thanks for telling me about the code tags.");
    }

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