Commons_Lang_StringUtils学习笔记

 

static String

abbreviate(String str,                     int maxWidth)           Abbreviates a String using ellipses.

可以返回长度为maxWidth的String，最右侧会使用...

觉得这个方法没啥用

 

 

static String

center(String str,             int size,             char padChar)           Centers a String in a larger String of size size

返回一个一个长度为size的字符串，原字符串居中（偏前），其他用padChar填充，若无此参数则使用" "填充

应该是一个有用的方法，另外这个方法重载，第三个参数可以是String，不过觉得没用

 

 

static String

chomp(String str)           Removes one newline from end of a String if it's there, otherwise leave it alone

将一个字符串末尾的换行符（/r 、/n、 /r/n）去掉。如果有多个则只去掉一次，注意/n/r只会去掉/r

 

 

static String

chop(String str)           Remove the last character from a String

去掉最后一个字符

 

 

static boolean

contains(CharSequence seq,                  CharSequence searchSeq)           Checks if CharSequence contains a search CharSequence, handling null.

查询seq是否包括searchSeq，我查看该方法才知道CharSequence是一个借口，String，StringBuilder，StringBuffer都实现了该接口。该方法重载，第二个参数也可以是char

 

 

static boolean

containsAny(CharSequence cs,                        CharSequence searchChars)            Checks if the CharSequence contains any character in the given set of characters.

查询cs是否包括searchChars的任意char（从any可以看出来），另外该方法重载，第二个参数可以是可变长参数char

 

 

static boolean

containsIgnoreCase(CharSequence str,                                      CharSequence searchStr)           Checks if CharSequence contains a search CharSequence irrespective of case, handling null.

上上个方法忽略大小写

 

 

static boolean

containsNone(CharSequence cs,                         char... searchChars)           Checks that the CharSequence does not contain certain characters.

与前面的方法相反，这里是没有包括，另外第二个参数可以为String

 

static boolean

containsOnly(CharSequence cs,                         char... valid)           Checks if the CharSequence contains only certain characters.

第二个参数可以为String

 

 

static boolean

containsWhitespace(CharSequence seq)           Check whether the given CharSequence contains any whitespace characters.

 

static int

countMatches(CharSequence str,                          CharSequence sub)           Counts how many times the substring appears in the larger string.

可以数出现多少次，觉得完胜前面返回boolean的方法啊

 

static String

defaultString(String str,                            String defaultStr)           Returns either the passed in String, or if the String is  null, the value of defaultStr.

当输入为null时转为defaultStr，这个应该很容易实现，另外这个方法重载，觉得没必要

 

static String

difference(String str1,                      String str2)           Compares two Strings, and returns the portion where they differ.

得到str2中不同于前者的部分，如果两个都是null则返回null，完全相同则是“”（注意str也为“”时）

 

static boolean	endsWith(CharSequence str,                  CharSequence suffix)           Check if a CharSequence ends with a specified suffix.
static boolean	endsWithAny(CharSequence string,                        CharSequence... searchStrings)           Check if a CharSequence ends with any of an array of specified strings.
static boolean	endsWithIgnoreCase(CharSequence str,                                      CharSequence suffix)           Case insensitive check if a CharSequence ends with a specified suffix.

比较一个字符串是否怎样结尾。

 

 

static boolean

equalsIgnoreCase(CharSequence str1,                                  CharSequence str2)           Compares two CharSequences, returning true if they are equal ignoring the case.

忽略大小写比较

 

 

static String

getCommonPrefix(String... strs)           Compares all Strings in an array and returns the initial sequence of characters that is common to all of them.

得到公有String，null作为参数会被视为“”

 

static int

indexOf(CharSequence seq,                CharSequence searchSeq,               int startPos)           Finds the first index within a CharSequence, handling null.

寻找是否有子字符串，第二个参数可以为char，第三个参数可以没有

还可以用lastIndexOf（）找最后一个

 

 

static int	indexOfAny(CharSequence cs,                     char... searchChars)           Search a CharSequence to find the first index of any character in the given set of characters.
static int	indexOfAny(CharSequence str,                      CharSequence... searchStrs)           Find the first index of any of a set of potential substrings.
static int	indexOfAny(CharSequence cs,                      String searchChars)           Search a CharSequence to find the first index of any character in the given set of characters.

 

static int	indexOfAnyBut(CharSequence cs,                           char... searchChars)           Searches a CharSequence to find the first index of any character not in the given set of characters.
static int	indexOfAnyBut(CharSequence seq,                            CharSequence searchChars)           Search a CharSequence to find the first index of any character not in the given set of characters.

寻找没有出现的char

 

 

static int

indexOfDifference(CharSequence... css)           Compares all CharSequences in an array and returns the index at which the CharSequences begin to differ.

寻找不一样的地方

 

static int

indexOfIgnoreCase(CharSequence str,                                    CharSequence searchStr,                                   int startPos)           Case in-sensitive find of the first index within a CharSequence from the specified position.

忽略大小写并可以指定位置

 

static boolean	isAllLowerCase(CharSequence cs)           Checks if the CharSequence contains only lowercase characters.
static boolean	isAllUpperCase(CharSequence cs)           Checks if the CharSequence contains only uppercase characters.
static boolean	isAlpha(CharSequence cs)           Checks if the CharSequence contains only Unicode letters.
static boolean	isAlphanumeric(CharSequence cs)           Checks if the CharSequence contains only Unicode letters or digits.
static boolean	isAlphanumericSpace(CharSequence cs)           Checks if the CharSequence contains only Unicode letters, digits or space (' ').
static boolean	isAlphaSpace(CharSequence cs)           Checks if the CharSequence contains only Unicode letters and space (' ').
static boolean	isAsciiPrintable(CharSequence cs)           Checks if the CharSequence contains only ASCII printable characters.
static boolean	isBlank(CharSequence cs)           Checks if a CharSequence is whitespace, empty ("") or null.
static boolean	isEmpty(CharSequence cs)           Checks if a CharSequence is empty ("") or null.
static boolean	isNotBlank(CharSequence cs)           Checks if a CharSequence is not empty (""), not null and not whitespace only.
static boolean	isNotEmpty(CharSequence cs)           Checks if a CharSequence is not empty ("") and not null.
static boolean	isNumeric(CharSequence cs)           Checks if the CharSequence contains only Unicode digits.
static boolean	isNumericSpace(CharSequence cs)           Checks if the CharSequence contains only Unicode digits or space (' ').
static boolean	isWhitespace(CharSequence cs)           Checks if the CharSequence contains only whitespace

 

 

static String	join(Iterable<?> iterable,         char separator)           Joins the elements of the provided Iterable into a single String containing the provided elements.
static String	join(Iterable<?> iterable,          String separator)           Joins the elements of the provided Iterable into a single String containing the provided elements.

 

将一组东西拼接起来，第一个参数可以是Object[]

 

static <T> String

join(T... elements)           Joins the elements of the provided array into a single String containing the provided list of elements.

 

 

static String

left(String str,         int len)           Gets the leftmost len characters of a String.

 

static String	leftPad(String str,               int size)           Left pad a String with spaces (' ').
static String	leftPad(String str,               int size,               char padChar)           Left pad a String with a specified character.
static String	leftPad(String str,               int size,                String padStr)           Left pad a String with a specified String.

 

static String

mid(String str,       int pos,       int len)           Gets len characters from the middle of a String.

 

static int

ordinalIndexOf(CharSequence str,                              CharSequence searchStr,                             int ordinal)           Finds the n-th index within a CharSequence, handling null.

寻找第n次出现的位置

 

static String

overlay(String str,                String overlay,               int start,               int end)           Overlays part of a String with another String.

覆盖

 

static String	remove(String str,             char remove)           Removes all occurrences of a character from within the source string.
static String	remove(String str,              String remove)           Removes all occurrences of a substring from within the source string.

 

移除

 

static String	removeEnd(String str,                    String remove)           Removes a substring only if it is at the end of a source string, otherwise returns the source string.
static String	removeEndIgnoreCase(String str,                                        String remove)           Case insensitive removal of a substring if it is at the end of a source string, otherwise returns the source string.
static String	removeStart(String str,                        String remove)           Removes a substring only if it is at the beginning of a source string, otherwise returns the source string.
static String	removeStartIgnoreCase(String str,                                            String remove)           Case insensitive removal of a substring if it is at the beginning of a source string, otherwise returns the source string.

 

static String	repeat(char ch,             int repeat)           Returns padding using the specified delimiter repeated to a given length.
static String	repeat(String str,             int repeat)           Repeat a String repeat times to form a new String.
static String	repeat(String str,              String separator,             int repeat)           Repeat a String repeat times to form a new String, with a String separator injected each time.

 

static String	replace(String text,                String searchString,                String replacement)           Replaces all occurrences of a String within another String.
static String	replace(String text,                String searchString,                String replacement,               int max)           Replaces a String with another String inside a larger String, for the first max values of the search String.

 

static String	replaceChars(String str,                         char searchChar,                         char replaceChar)           Replaces all occurrences of a character in a String with another.
static String	replaceChars(String str,                          String searchChars,                          String replaceChars)           Replaces multiple characters in a String in one go.

 

替换，如果后面长度不够则重复补齐，如果超了则丢弃

 

 

static String

replaceOnce(String text,                        String searchString,                        String replacement)           Replaces a String with another String inside a larger String, once.

 

static String

reverseDelimited(String str,                                 char separatorChar)           Reverses a String that is delimited by a specific character.

 

从一个分割位开始反转

 

static String[]

split(String str,            String separatorChars,           int max)           Splits the provided text into an array with a maximum length, separators specified.

 

max是指定分割后数组长度，可以为0，就相当于没有，也就是无次数限制

 

 

static boolean	startsWith(CharSequence str,                      CharSequence prefix)           Check if a CharSequence starts with a specified prefix.
static boolean	startsWithAny(CharSequence string,                            CharSequence... searchStrings)           Check if a CharSequence starts with any of an array of specified strings.
static boolean	startsWithIgnoreCase(CharSequence str,                                          CharSequence prefix)           Case insensitive check if a CharSequence starts with a specified prefix.

 

static String	strip(String str)           Strips whitespace from the start and end of a String.
static String	strip(String str,            String stripChars)           Strips any of a set of characters from the start and end of a String.

 

static String[]	stripAll(String... strs)           Strips whitespace from the start and end of every String in an array.
static String[]	stripAll(String[] strs,                  String stripChars)           Strips any of a set of characters from the start and end of every String in an array.

批量strip

static String	stripEnd(String str,                  String stripChars)           Strips any of a set of characters from the end of a String.
static String	stripStart(String str,                      String stripChars)           Strips any of a set of characters from the start of a String.
static String	stripToEmpty(String str)           Strips whitespace from the start and end of a String  returning an empty String if null input.
static String	stripToNull(String str)           Strips whitespace from the start and end of a String  returning  null if the String is empty ("") after the strip.

 

static String	substringAfter(String str,                              String separator)           Gets the substring after the first occurrence of a separator.
static String	substringAfterLast(String str,                                      String separator)           Gets the substring after the last occurrence of a separator.
static String	substringBefore(String str,                                String separator)           Gets the substring before the first occurrence of a separator.
static String	substringBeforeLast(String str,                                        String separator)           Gets the substring before the last occurrence of a separator.
static String	substringBetween(String str,                                  String tag)           Gets the String that is nested in between two instances of the same String.
static String	substringBetween(String str,                                  String open,                                  String close)           Gets the String that is nested in between two Strings.
static String[]	substringsBetween(String str,                                    String open,                                    String close)           Searches a String for substrings delimited by a start and end tag, returning all matching substrings in an array.

各种截取

 

static String

swapCase(String str)           Swaps the case of a String changing upper and title case to lower case, and lower case to upper case.

反转大小写

 

static String	trim(String str)           Removes control characters (char <= 32) from both ends of this String, handling null by returning  null.
static String	trimToEmpty(String str)           Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is null.
static String	trimToNull(String str)           Removes control characters (char <= 32) from both ends of this String returning null if the String is empty ("") after the trim or if it is null.