The method would be useful when checking for presence of certain pattern text on
the input. For example checking for "abcde" currently needs to be written as

int c;
if ((c = input.read()) == 'a'
 && (c = input.read()) == 'b'
 && (c = input.read()) == 'c'
 && (c = input.read()) == 'd'
 && (c = input.read()) == 'e') {
    // Possibly check the next character whether it's delimiter etc.
} else {
    // Check what was the c character that did not match
    // Whether it was delimiter or e.g. alphanumeric letter
}

With the match() method and a special constant MATCH this could be rewritten as

int c;
if ((c = input.match("abcde")) == LexerInput.MATCH) {
    // Possibly check the next character whether it's delimiter etc.
} else {
    // Check what was the c character that did not match
    // Whether it was delimiter or e.g. alphanumeric letter
}