public StrBuilder delTo(int newPosition) {
		if (newPosition < 0) {
			newPosition = 0;
		}
		return del(newPosition, this.position);
	}
@Test
	public void delToTest() {
		StrBuilder strBuilder = new StrBuilder("ABCDEFG");

		// 不处理
		StrBuilder builder = strBuilder.delTo(7);
		assertEquals("ABCDEFG", builder.toString());

		// 删除全部
		builder = strBuilder.delTo(0);
		assertEquals("", builder.toString());
	}