Depending on your program context, you can just drop all text from the error stream's output during corenlp execution.
// this is your print stream, store the reference PrintStream err = System.err; // now make all writes to the System.err stream silent System.setErr(new PrintStream(new OutputStream() { public void write(int b) { } })); // YOUR CODE HERE // set everything bck to its original state afterwards System.setErr(err);