Java replaceAll不区分大小写

Java 中replaceAll如何忽略大小写呢?

方式一:在正则表达式前面添加(?i)

1. @Test
2. public void test_replaceAll33(){
3. String input = "I like Java,jAva is very easy and jaVa is so popular.";
4. String replacement="cccc";
5. System.out.println(input);
6. System.out.println(input.replaceAll("(?i)java", replacement));
7. }

@Test
	public void test_replaceAll33(){
		String input = "I like Java,jAva is very easy and jaVa is so popular.";
		String replacement="cccc";

		System.out.println(input);
		System.out.println(input.replaceAll("(?i)java", replacement));
	}

测试结果:

方式二:使用Matcher 的appendReplacement 方法

1. @Test
2. public void test_replaceAll(){
3. String input = "I like Java,jAva is very easy and jaVa is so popular.";
4. String regex = "java";
5. String replacement="cccc";
6. StringBuffer sb =replaceAll2(input, regex, replacement);
7. System.out.println(input);
8. System.out.println(sb);
9. }
10. /***
11. * replaceAll,忽略大小写
12. * @param input
13. * @param regex
14. * @param replacement
15. * @return
16. */
17. public StringBuffer replaceAll2(String input,String regex,String replacement){
18. Pattern p = Pattern.compile(regex,Pattern.CASE_INSENSITIVE);
19. Matcher m = p.matcher(input);
20. StringBuffer sb = new StringBuffer();
21. boolean result = m.find();
22. while (result)
23. {
24. m.appendReplacement(sb, replacement);
25. result = m.find();
26. }
27. m.appendTail(sb);
28. return sb;
29. }

@Test
	public void test_replaceAll(){
		String input = "I like Java,jAva is very easy and jaVa is so popular.";
        String regex = "java";
        String replacement="cccc";

        StringBuffer sb =replaceAll2(input, regex, replacement);
        System.out.println(input);
        System.out.println(sb);

	}
	/***
	 * replaceAll,忽略大小写
	 * @param input
	 * @param regex
	 * @param replacement
	 * @return
	 */
	public StringBuffer replaceAll2(String input,String regex,String replacement){
		 Pattern p = Pattern.compile(regex,Pattern.CASE_INSENSITIVE);
	        Matcher m = p.matcher(input);
	        StringBuffer sb = new StringBuffer();
	        boolean result = m.find();
	        while (result)
	        {
	            m.appendReplacement(sb, replacement);
	            result = m.find();
	        }
	        m.appendTail(sb);
	        return sb;
	}

测试结果:

方式三:使用Matcher 的replaceAll

1. /***
2. * replaceAll,忽略大小写
3. *
4. * @param input
5. * @param regex
6. * @param replacement
7. * @return
8. */
9. public String replaceAll3(String input, String regex, String replacement) {
10. Pattern p = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);
11. Matcher m = p.matcher(input);
12. String result = m.replaceAll(replacement);
13. return result;
14. }
15. @Test
16. public void test_replaceAll3() {
17. String input = "I like Java,jAva is very easy and jaVa is so popular.";
18. String regex = "java";
19. String replacement = "cccc";
20. String sb = replaceAll3(input, regex, replacement);
21. System.out.println(input);
22. System.out.println(sb);
23. }

/***
	 * replaceAll,忽略大小写
	 *
	 * @param input
	 * @param regex
	 * @param replacement
	 * @return
	 */
	public String replaceAll3(String input, String regex, String replacement) {
		Pattern p = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);
		Matcher m = p.matcher(input);
		String result = m.replaceAll(replacement);
		return result;
	}

	@Test
	public void test_replaceAll3() {
		String input = "I like Java,jAva is very easy and jaVa is so popular.";
		String regex = "java";
		String replacement = "cccc";

		String sb = replaceAll3(input, regex, replacement);
		System.out.println(input);
		System.out.println(sb);

	}

测试结果: 参考:http://hw1287789687.iteye.com/blog/2150892