Compiler error cannot find symbol - Java

First, I am very new to Java and my programming in general is rusty. So I might have missed something very simple.

The error:

cannot find symbol
symbol  : method setMethod(java.lang.String)
location: class ij.plugin.Thresholder
        Thresholder.setMethod("Mean");

Some code snippets: This part is third party code. I would like to avoid modifying this as much as possible

public class Thresholder implements PlugIn, Measurements, ItemListener {
    private static String staticMethod = methods[0];

    public static void setMethod(String method) {
        staticMethod = method;
    }
}

My code (well, some relevant parts)

    import ij.plugin.Thresholder;
    public class CASA_ implements PlugInFilter,Measurements  {
    public void run(ImageProcessor ip) {
        track(imp, minSize, maxSize, maxVelocity);
    }

    public void track(ImagePlus imp, float minSize, float maxSize, float maxVelocity) {
        Thresholder.setMethod("Mean");         <-- This is the line the compiler hates
    }
}

Why is the compiler looking for a setMethod method with a return of something other than void?

Thanks

Copyright Notice：Content Author:「user2425977」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/16778703/compiler-error-cannot-find-symbol-java