Java class notes------string API

*intLength ()*gets the number of characters (length) in the current string, both Chinese and English*Each character is counted as a length str.length (); *intindexOf (String str)*finds the position of the given string for the first occurrence in the current string. *The return value is the first character of the given string in the current string subscript*because Java is case sensitive, you must match all of the above to return a specific subscript. Index= Str.indexof ("in"); *intIndexOf (String str,intFrom )*Overloaded methods:*finds the position of the first occurrence of the given string, starting at the specified subscript position in the current string. * Similarly, if not found will return-1. Index= Str.indexof ("In", 3); *intlastIndexOf (String str)*finds the position of the last occurrence of the given string in the current string index= Str.lastindexof ("in"); *get some of the contents of a string* String substring (intStartintend)*starts from the specified subscript start and intercepts the specified subscript end*Note that the character that does not contain the end position is the string between the points. *the Java API typically uses 2 numbers to denote a range, usually* "With head does not contain tail"the. Str.substring (4,9); *String trim ()*removes blank string trim from both sides of the current string=Str.trim (); *CharCharAt (intindex)*gets the character that corresponds to the specified position in the current stringCharc = Str.charat (9); *BooleanStartsWith (String str)*BooleanEndsWith (String str)*determines whether the current string begins with the given string, and the other*is whether the end of the given string is judged. BooleanStarts = Str.startswith ("Think"); BooleanEnds = Str.endswith ("Ava"); *String touppercase ()*String toLowerCase ()*converts the English part of the current string to all-uppercase and all-lowercase string upper=str.touppercase (); String Lower=str.tolowercase (); //usually used to ignore case judgments (e.g. verification code judgment)*StaticString valueOf ()*The string provides a number of static methods valueof ()*the effect is to convert other types to strings. The more commonly used is to*the base type is converted to a string. String S1= String.valueof (123);//"123"String S2= String.valueof (123.123);//"123.123"//The result of any type-to-string connection is a string. String s3 = 123+ ""; *Java.lang.StringBuilder*internally maintains a variable array of characters. To resolve frequent modifications*the performance loss caused by string content. *A related method for editing a string is provided internally:*additions and deletions StringBuilder SB=NewStringBuilder ("123456"); *StringBuilder Append (String str)*appends the given content to the end of the current string Sb.append ("789"); //Gets the StringBuilder internal edited stringstr =sb.tostring (); * StringBuilder Delete (intStartintend)*deletes a string from the current string within a given range Sb.delete (1, 2); * StringBuilder Insert (intoffset,string str)*inserts the given string content at the specified position Sb.insert (2, "456"); * StringBuilder Replace (intStartintend,string str)*replaces a string in the given range in the current string with the given string Sb.replace (0, 2, "456"); //Invert stringSb.reverse (); *Booleanmatches (String regex)*verifies that the current string satisfies the formatting requirements of a given regular expression* Note: Whether or not the regular expression uses "^", "$"are all*Match Validation String str= "[Email protected]"; * [A-za-z0-9_][email protected][a-za-z0-9_]+ (\.[ a-z]+) +String regex= "[A-za-z0-9_][email protected][a-za-z0-9_]+ (\\.[ a-z]+) + "; BooleanMatches =str.matches (regex); *string[] Split (String regex)* "Cut off" the part of the current string that satisfies the regular expression, keep the remainder.        Splits a string operation. String Str= "ABC123JH452FH748HF870SDFS5AQ75QEW"; String[] Array= Str.split ("[0-9]+"); *string ReplaceAll (String regex,string str)*replaces the content in the current string that satisfies the regular expression part with the*the string given by string str= "Fhhf132fhg67fh606fhf234assd798dgh"; /** Replace the number part in the current string with "#NUMBER #"*/Str= Str.replaceall ("\\d+", "#NUMBER #"); 

Java class notes------string API