Help with quadratic equation in java

Hi, I'm looking to do some error trapping for the quadratic equation.
How would put this into a while statement?
Here's the psudeocode

Code:

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while (sqrt is negative)
      println("The answer is imaginary")

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Thanks.

while (Math.sqrt(<some double value>) < 0) {
System.out.println("The square root is less than 0");
}