java 常用方法

java 常用方法:

(1)去掉所有的回车换行

/**
	 * delete CRLF; delete empty line ;delete blank lines
	 * 
	 * @param input
	 * @return
	 */
	public static String deleteCRLF(String input) {
		input = SystemHWUtil.deleteCRLFOnce(input);
		return SystemHWUtil.deleteCRLFOnce(input);
	}
/***
	 * delete CRLF; delete empty line ;delete blank lines
	 * 
	 * @param input
	 * @return
	 */
	private static String deleteCRLFOnce(String input) {
		if (ValueWidget.isHasValue(input)) {
			return input.replaceAll("((\r\n)|\n)[\\s\t ]*(\\1)+", "$1")
					.replaceAll("^((\r\n)|\n)", "");
		} else {
			return null;
		}
	}

 使用时直接调用deleteCRLF方法即可

(2)去掉所有的空格

/***
	 * Delete all spaces
	 * 
	 * @param input
	 * @return
	 */
	public static String deleteAllCRLF(String input) {
		return input.replaceAll("((\r\n)|\n)[\\s\t ]*", "").replaceAll(
				"^((\r\n)|\n)", "");
	}

 

(3)去掉String[]中重复的元素,去重

	/***
	 * test ok!<br> 去重
	 * @param strs
	 * @return
	 */
	public static String[] guolv(String[]strs){
		List<String>list =new ArrayList<String>();
		list.add(strs[0]);//数组的第一个元素
		for(int i=1;i<strs.length;i++){
			String  string=strs[i];
			if(!isContains(list, string)){
				list.add(string);
			}
		}
		return list2Arr(list);
	}
/***
	 * 判断list中是否包含keyWord
	 * 
	 * @param list
	 * @param keyWord
	 * @return
	 */
	public static boolean isContains(List<String> list, String keyWord) {
		if (ValueWidget.isNullOrEmpty(list)) {
			return false;
		}
		return list.contains(keyWord);
	}
/***
	 * convert List to String[]
	 * @param list
	 * @return
	 */
	public static String[] list2Arr(List list){
		int size=list.size();
		String[]strs=new String[size];
		for(int i=0;i<size;i++){
			strs[i]=(String)list.get(i);
		}
		return strs;	
	}

 

(4)把List 转化为String[]

/***
	 * convert List to String[]
	 * @param list
	 * @return
	 */
	public static String[] list2Arr(List list){
		int size=list.size();
		String[]strs=new String[size];
		for(int i=0;i<size;i++){
			strs[i]=(String)list.get(i);
		}
		return strs;	
	}

 (5)获取目录中的文件名

/***
	 * 获取文件名称。例如"aa/bb我们#.txt"-->“bb我们#.txt”
	 * 
	 * @param filepath
	 * @return
	 */
	public static String getFileNameOnly(String filepath) {
		String result = filepath.replaceAll(".*\\b[/\\\\]([\\w\\.]+)", "$1");
		return result;
	}

 注意:目录的类型是字符串

(6)过滤掉List中相同的元素

/***
	 * 过滤掉其中相同的元素,test ok
	 * 
	 * @param list
	 * @param propertyName
	 * @param propertyValue
	 * @return
	 * @throws SecurityException
	 * @throws IllegalArgumentException
	 * @throws NoSuchFieldException
	 * @throws IllegalAccessException
	 */
	public static List<?> uniqueObject(List<?> list, String propertyName)
			throws SecurityException, IllegalArgumentException,
			NoSuchFieldException, IllegalAccessException {
		if (ValueWidget.isNullOrEmpty(list)) {
			return list;
		}
		List resultList = new ArrayList();
		resultList.add(list.get(0));
		for (int i = 1; i < list.size(); i++) {
			Object obj = list.get(i);
			if (!isContainObject(resultList, propertyName,
					(String) ReflectHWUtils.getObjectValue(obj, propertyName))) {
				resultList.add(obj);
			}
		}
		return resultList;
	}

/***
	 * 判断 list 中是否已经存在该对象
	 * 
	 * @param list
	 * @param propertyName
	 * @param propertyValue
	 * @return
	 * @throws SecurityException
	 * @throws IllegalArgumentException
	 * @throws NoSuchFieldException
	 * @throws IllegalAccessException
	 */
	public static boolean isContainObject(List list, String propertyName,
			String propertyValue) throws SecurityException,
			IllegalArgumentException, NoSuchFieldException,
			IllegalAccessException {
		if (ValueWidget.isNullOrEmpty(list)) {
			return false;
		}
		for (int i = 0; i < list.size(); i++) {
			Object obj = list.get(i);
			String propertyValue2 = (String) ReflectHWUtils.getObjectValue(obj,
					propertyName);
			if (propertyValue.equals(propertyValue2)) {
				return true;
			}
		}
		return false;
	}
/***
	 * 获取指定对象的属性值
	 * 
	 * @param obj
	 * @param propertyName
	 * @return
	 * @throws SecurityException
	 * @throws NoSuchFieldException
	 * @throws IllegalArgumentException
	 * @throws IllegalAccessException
	 */
	public static Object getObjectValue(Object obj, String propertyName)
			throws SecurityException, NoSuchFieldException,
			IllegalArgumentException, IllegalAccessException {
		if (StringUtils.isEmpty(propertyName)) {
			return null;
		}
		Class<?> clazz = obj.getClass();
		Field name = getSpecifiedField(clazz, propertyName);
		if (ValueWidget.isNullOrEmpty(name)) {
			propertyName=ValueWidget.title(propertyName);//convert "Key2" to "key2"
			name = getSpecifiedField(clazz, propertyName);
			
			if (ValueWidget.isNullOrEmpty(name)) {
				System.out.println("[ReflectHWUtils.getObjectValue]"
						+ obj.getClass().getName() + " does not has field "
						+ propertyName);
			return null;
			}
		}
		return getObjectValue(obj, name);
	}

 注意:List中的元素不是基本类型