A DESCRIPTION OF THE PROBLEM :
in java.lang.String source code
new String(char value[], int offset, int count) method
if (count <= 0) {
            if (count < 0) {
                throw new StringIndexOutOfBoundsException(count);
            }if (offset <= value.length) {
                this.value = "".value;
                return;
            }
        }
appear duplicate Judgment.on change
if (count < 0) {
                throw new StringIndexOutOfBoundsException(count);
            }
if(count == 0){ }
efficiency will be better