The code uses non-short-circuit logic (|) rather than short-circuit logic (||). Non-short-circuit logic causes both sides of the expression to be evaluated even when the result can be inferred from knowing the left-hand side.

$ pwd
/local-copy/1.6.0-rc-b69_src/j2se/src/share/classes/javax/imageio
$ tail +1095 ImageTypeSpecifier.java | head -6
    public int getBitsPerBand(int band) {
        if (band < 0 | band >= getNumBands()) { // <<------- here
            throw new IllegalArgumentException("band out of range!");
        }
        return sampleModel.getSampleSize(band);
    }