Java 常用字符操作

java 中常用的字符串操作

1,判断字符是否是普通字符(a-z,A-Z,0-9,下划线_,英文句点.)

必须是英文大小写,数字,下划线,英文句号

/***
	 * 是否是普通字符(a-z,A-Z,0-9,下划线_,英文句点.)
	 * @param c
	 * @return
	 */
	public  static boolean isWordChar(char c){
		int number22=(int)c;
		if((number22>=97/*a*/ && number22<=122/*z*/)
				||(number22>=65/*A*/ && number22<=90/*Z*/)
				||(number22>=48/*0*/ && number22<=57/*9*/)
				||number22==95/*下划线*/
				||number22==46/*英文的句点.*/){
//			System.out.println("is word");
			return true;
		}else{
			return false;
		}
	}

 测试:

@Test
	public void tst2(){
		char c='_';
		System.out.println(isWordChar(c));
		Assert.assertEquals(true, isWordChar(c));
		
		c=',';
		Assert.assertEquals(false, isWordChar(c));
		
		c='a';
		Assert.assertEquals(true, isWordChar(c));
		
		c='z';
		Assert.assertEquals(true, isWordChar(c));
		
		c='A';
		Assert.assertEquals(true, isWordChar(c));
		
		c='Z';
		Assert.assertEquals(true, isWordChar(c));
		
		c='0';
		Assert.assertEquals(true, isWordChar(c));
		
		c='9';
		Assert.assertEquals(true, isWordChar(c));
		
		c=' ';
		Assert.assertEquals(false, isWordChar(c));
		
		c='.';
		Assert.assertEquals(true, isWordChar(c));
	}

 2,判断字符串是否是普通字符

必须以字母开头,可以包含(a-z,A-Z,0-9,下划线_,英文句点.),但是不能以句点结尾,不能连续两个句点

/***
	 * 必须以字母开头,可以包含(a-z,A-Z,0-9,下划线_,英文句点.),但是不能以句点结尾,不能连续两个句点
	 * @param input
	 * @return
	 */
	public static boolean isWord(String input){
		char c=input.charAt(0);
		if(!isWordChar(c)){
			System.out.println("不是单词");
			return false;
		}
		
		int number22=(int)c;
		if((number22>=48/*0*/ && number22<=57/*9*/)
				||number22==95/*下划线*/||number22==46/*英文的句点.*/){
			return false;
		}
		int length22=input.length();
		int lastChar =(int)input.charAt(length22-1);//最后一个char
		if(lastChar==46/*英文的句点.*/){
			return false;
		}
		for(int j=1;j<length22;j++){
			if(!isWordChar(input.charAt(j))){
				return false;
			}
		}
		//不能有连续两个英文句点
		if(SystemHWUtil.findStr3(input, SystemHWUtil.ENGLISH_PERIOD+SystemHWUtil.ENGLISH_PERIOD)>0){
			System.out.println("不能有连续两个英文句点");
			return false;
		}
		return true;
	}

 测试:

@Test
	public void tetst2(){
		String input="abc,";
		System.out.println(isWord(input));
		Assert.assertEquals(false, isWord(input));
		
		input="abc.a";
		Assert.assertEquals(true, isWord(input));
		
		input="1abc,";
		Assert.assertEquals(false, isWord(input));
		
		input="a111bc,";
		Assert.assertEquals(false, isWord(input));
		
		input="ab.a.c";
		Assert.assertEquals(true, isWord(input));
		
		input="ab..c";
		Assert.assertEquals(false, isWord(input));
	}

 3,判断是否是空字符

空字符包括:(空格,Tab,换行,回车)

/***
	 * 是否是空格(空格,Tab)
	 * @param c
	 * @return
	 */
	public static boolean isBlank(char c) {
		int number22 = (int) c;
//		System.out.println(number22);
		if(number22==32/*空格*/||number22==9/*Tab*/
				||number22==10/*\n*/||number22==13/*\r*/){
			return true;
		}
		return false;
	}

 测试:

@Test
	public void test444(){
		char c='\n';
		System.out.println((int)c);
		System.out.println(OAUtil.isBlank(c));
		Assert.assertEquals(true, OAUtil.isBlank(c));
		
		c = '.';
		Assert.assertEquals(false, OAUtil.isBlank(c));
		
		c = ' ';
		Assert.assertEquals(true, OAUtil.isBlank(c));
		
		c = '	'/*Tab*/;
		Assert.assertEquals(true, OAUtil.isBlank(c));
	}

 

 

4,搜索字符串,若找到,则返回当时的索引,否则返回-1

/***
	 * 当发现keyWord的时候读到的index,<br>如果没有发现,则始终返回-1
	 * @param srcText
	 * @param keyWord
	 * @param pos
	 * @return
	 */
	public static int findReadLength(String srcText, String keyWord, int pos) {
		int i, j/*, k = 0*/;
		i = pos;
		j = 0;
		while (i < srcText.length() && j < keyWord.length()) {
			if (srcText.charAt(i) == keyWord.charAt(j)) {
				++i;
				++j;
				if (j == keyWord.length()) {

					return i;
				}
			} else {
				i = i - j + 1;
				j = 0;
			}
		}
		return SystemHWUtil.NEGATIVE_ONE;
	}

 测试:

@Test
	public void test_findReadLength(){
		String srcText="abc";
		System.out.println(SystemHWUtil.findReadLength(srcText, "abc", 0));
		Assert.assertEquals(3, SystemHWUtil.findReadLength(srcText, "abc", 0));
		
		srcText=" abc";
		Assert.assertEquals(4, SystemHWUtil.findReadLength(srcText, "abc", 0));
		
		srcText=" abcabc";
		Assert.assertEquals(4, SystemHWUtil.findReadLength(srcText, "abc", 0));
		
		srcText=" ab c";
		Assert.assertEquals(-1, SystemHWUtil.findReadLength(srcText, "abc", 0));
		
		srcText="aababbabc";
		Assert.assertEquals(9, SystemHWUtil.findReadLength(srcText, "abc", 0));
	}

 源代码见附件