今天在做一個正則表示式的解析時，突然看見一個？：的例子，就看不懂了，然後在網上查了下，竟然是非捕獲型括號，意思就是匹配pattern，但不包含在match的group方法裡面。

        (?:  pattern)是非捕獲型括號  匹配pattern，但不捕獲匹配結果。
        (pattern )是捕獲型括號。  匹配pattern，匹配pattern並捕獲結果,自動獲取組號

深入瞭解還得看例子：

例一：

	@Test
	public void test9(){
		
		
		Pattern p = Pattern.compile("(\\d+,)(\\w+)");

		String s = "123,abc-78,def";
		Matcher m = p.matcher(s);
		while(m.find())
		{
		  System.out.println("m.group():"+m.group()); //列印所有
		  System.out.println("m.group(1):"+m.group(0)); //列印所有
		  System.out.println("m.group(1):"+m.group(1)); //列印數字的
		  System.out.println("m.group(2):"+m.group(2)); //列印字母的
		}		
	}
 

輸出：

m.group():123,abc
m.group(1):123,abc
m.group(1):123,
m.group(2):abc
m.group():78,def
m.group(1):78,def
m.group(1):78,
m.group(2):def

例二：

@Test
	public void test10(){
		
		
		Pattern p = Pattern.compile("(\\d+)-(\\d+)-(\\d+)\\s+([A-z]+)\\s+([A-z]+)\\s+(\\d+):(\\d+)");
		
		String s = "2013-10-26 wei test 15:39";
		Matcher m = p.matcher(s);
		
		if(m.find())
		{
			System.out.println(m.groupCount());
			System.out.println("m.group():"+m.group()); //2013-10-26 wei test 15:39
			System.out.println("m.group():"+m.group(0)); //2013-10-26 wei test 15:39
			System.out.println("m.group(1):"+m.group(1)); //2013
			System.out.println("m.group(2):"+m.group(2)); //10
			System.out.println("m.group(3):"+m.group(3)); //26
			System.out.println("m.group(4):"+m.group(4)); //wei
			System.out.println("m.group(5):"+m.group(5)); //test
			System.out.println("m.group(6):"+m.group(6)); //15
			System.out.println("m.group(7):"+m.group(7)); //39
		}		
	}
 

例三：

@Test
	public void test11(){
		
		
		Pattern p = Pattern.compile("((\\d+)-(\\d+)-(\\d+))\\s+([A-z]+)\\s+([A-z]+)\\s+((\\d+):(\\d+))");
		
		String s = "2013-10-26 wei test 15:39";
		Matcher m = p.matcher(s);
		if(m.find())
		{
			System.out.println("m.group():"+m.group()); //2013-10-26 wei test 15:39
			System.out.println("m.group():"+m.group(0)); //2013-10-26 wei test 15:39
			System.out.println("m.group(1):"+m.group(1)); //2013-10-26
			System.out.println("m.group(2):"+m.group(2)); //2013
			System.out.println("m.group(3):"+m.group(3)); //10
			System.out.println("m.group(4):"+m.group(4)); //26
			System.out.println("m.group(5):"+m.group(5)); //wei
			System.out.println("m.group(6):"+m.group(6)); //test
			System.out.println("m.group(7):"+m.group(7)); //15:39
			System.out.println("m.group(8):"+m.group(8)); //15
			System.out.println("m.group(9):"+m.group(9)); //39
		}		
	}
 

例四：

@Test
	public void test12(){
		
		
		Pattern p = Pattern.compile("((?:\\d+)-(\\d+)-(\\d+))\\s+([A-z]+)\\s+([A-z]+)\\s+((\\d+):(\\d+))");
		
		String s = "2013-10-26 wei test 15:39";
		Matcher m = p.matcher(s);
		if(m.find())
		{
			System.out.println(m.groupCount());//8
			System.out.println("m.group():"+m.group()); //2013-10-26 wei test 15:39
			System.out.println("m.group():"+m.group(0)); //2013-10-26 wei test 15:39
			System.out.println("m.group(1):"+m.group(1)); //2013-10-26
			System.out.println("m.group(2):"+m.group(2)); //10
			System.out.println("m.group(3):"+m.group(3)); //26
			System.out.println("m.group(4):"+m.group(4)); //wei
			System.out.println("m.group(5):"+m.group(5)); //test
			System.out.println("m.group(6):"+m.group(6)); //15:39
			System.out.println("m.group(7):"+m.group(7)); //15
			System.out.println("m.group(8):"+m.group(8)); //39
			
		}		
	}

例五：

@Test
	public void test13(){
		
		
		Pattern p = Pattern.compile("(?:(?:\\d+)-(\\d+)-(\\d+))\\s+([A-z]+)\\s+([A-z]+)\\s+((\\d+):(\\d+))");
		
		String s = "2013-10-26 wei test 15:39";
		Matcher m = p.matcher(s);
		if(m.find())
		{
			System.out.println(m.groupCount());//7
			System.out.println("m.group():"+m.group()); //2013-10-26 wei test 15:39
			System.out.println("m.group():"+m.group(0)); //2013-10-26 wei test 15:39
			System.out.println("m.group(1):"+m.group(1)); //10
			System.out.println("m.group(2):"+m.group(2)); //26
			System.out.println("m.group(3):"+m.group(3)); //wei
			System.out.println("m.group(4):"+m.group(4)); //test
			System.out.println("m.group(5):"+m.group(5)); //15:39
			System.out.println("m.group(6):"+m.group(6)); //15
			System.out.println("m.group(7):"+m.group(7)); //39
		}		
	}