@Override
	public int start(int from) {
		Assert.notNull(this.text, "Text to find must be not null!");
		final int limit = getValidEndIndex();
		if(negative){
			for (int i = from; i > limit; i--) {
				if (NumberUtil.equals(c, text.charAt(i), caseInsensitive)) {
					return i;
				}
			}
		} else{
			for (int i = from; i < limit; i++) {
				if (NumberUtil.equals(c, text.charAt(i), caseInsensitive)) {
					return i;
				}
			}
		}
		return -1;
	}
@Test
	public void negativeStartTest(){
		int start = new CharFinder('a').setText("cba123").setNegative(true).start(2);
		assertEquals(2, start);

		start = new CharFinder('2').setText("cba123").setNegative(true).start(2);
		assertEquals(-1, start);

		start = new CharFinder('c').setText("cba123").setNegative(true).start(2);
		assertEquals(0, start);
	}