Java--string class

OneString Common Methods

1 Importjava.util.Arrays;2 3  Public classStringdemo {4      Public Static voidMain (string[] args) {5String str = "String Method";6         //determines whether a string is empty7 str.isempty ();8         //Get string length9 str.length ();Ten         //remove the opening and closing spaces One Str.trim (); A  -         //finds the first found character or string index position in string 0 to the end, no return-1 -         //public int indexOf (String str) the         //public int indexOf (int ch) -         intindex = str.indexof ("ing");//3 -index = str.indexof (' i ');//3 -         //FromIndex from this index (contains) the location of the search, that is, FromIndex to the end +         //public int indexOf (int ch, fromIndex) -         //public int indexOf (String ch, fromIndex) +index = str.indexof (' i ', 3);//3 A         //LastIndexOf, similar to the IndexOf method, looks from the back to index 0 atindex = str.lastindexof (' i '); -  -         //whether the string contains the specified sequence of characters, string is the implementation of the interface Charsequence -         //Public Boolean contains (charsequence s) -         //internal is realization: return IndexOf (S.tostring ()) >-1; -         Booleanct = str.contains ("ing");//true in  -         //determines whether a string begins with a given substring to         //Public boolean startsWith (String prefix) +         Booleanst = Str.startswith ("str");//true -         //Public boolean startsWith (String prefix, int toffset) the         //Toffset indicates the starting position *st = Str.startswith ("str", 2);//false $         //determines whether a string ends with a given substringPanax Notoginseng         //Public boolean endsWith (String suffix) -         Booleaned = str.endswith ("FA");//true the  +         //compare with other strings to see if the content is the same A         //Public Boolean equals (Object anobject) the  +         //Ignore case, compare with other strings to see if content is the same -         //Public Boolean equalsignorecase (String anotherstring) $"abc". Equals ("abc");//false $"ABC". EQUALSIGNORECASE ("abc");//true -  -         //turn case, return new string, original string unchanged theStr.tolowercase ();//lowercase -Str.touppercase ();//UppercaseWuyi  the         //string comparison size, according to the encoded value -         //public int CompareTo (String anotherstring) Wu"ABC". COMPARETO ("abc");//+ = Return ' A '-' a ' character by comparison -         //Ignore letter Case for comparison (both turn uppercase and then Compare) About         //public int comparetoignorecase (String str) $  -         //intercepts a string to return a new string -         //Public String substring (int beginindex) -         //Public String substring (int beginindex, int endIndex) A         //Index of beginindex start index EndIndex end +         //Beginindex are included in the interception range, while Endindex does not include theString sub = str.substring (1);//Tring Method -String Sube = str.substring (1, 2);//T $  the         //string concatenated, returns the current string and the string after the argument string is merged, the original string is unchanged the         //Public string concat (String str) theString cc = Str.concat ("--concat connection method"); the         //String Method--Concat connection method -  in         //string substitution, return new string, original string unchanged the         //Replace a single character the         //Public String Replace (char OldChar, char Newchar) AboutString RP = str.replace (' square ', ' Circle ');//String Round Method the         //Replace character sequence the         //Public String replace (charsequence target, charsequence replacement) theRP = str.replace ("String", "replace");//Replace Method +         //use regular to select the characters you want to replace -         //regex-to-regular-expression string the         //replacement replaced elementsBayi         //Public string ReplaceAll (string regex, string replacement) theRP = Str.replaceall ("[A-Z]", "I");//Siiiii Method the         //indicates: will match to each lowercase letter, change to I -         //Replacefirst Changing a string that meets the requirements for the first time -RP = Str.replacefirst ("[A-Z]", "I"); the  the         //separates strings, returns an array of delimited substrings, the original string unchanged the         //The regex is separated by a string and the matched string is removed the         //Public string[] Split (String regex) -string[] STRs = "HELLO World This Night". Split (""); the System.out.println (Arrays.aslist (STRs)); the         //[HELLO, World, this, night] theSTRs = "HELLO World This Night". Split ("H");94 System.out.println (Arrays.aslist (STRs)); the         //[, Ello World T, is Nig, T] the  the         //limit delimited number of limits (LIMIT-1)98         //It can also be understood that the number of matches to the regex is limit-1 About         //if the number of limits (LIMIT-1) is greater than the number of actual separators -         //or limit-1 < 0101         //then the normal separation is unrestricted. 102         //"HELLO World This Night". Split ("") such a separation103         //Public string[] Split (string regex, string limit);104          for(inti =-1; I < 6; i++) { theSTRs = "HELLO World This Night". Split ("", i);106 System.out.println (Arrays.aslist (STRs));107         }108         /**109 * can actually be separated 3 times, can be obtained array length of 4 the          * 111 *-1 [HELLO, World, this, night] the * 0 [HELLO, World, this, night]113 * 1 [HELLO World This Night] the * 2 [HELLO, World this night] the * 3 [HELLO, World, this night] the * 4 [HELLO, World, this, night]117 * 5 [HELLO, World, this, night]118          */119     } - 121}

Two, the construction method of String

Java--string class