Java starts from zero 30 (string and StringBuffer classes)

StringBuffer Connection character operation use StringBuffer to use the Append () method in StringBuffer when the contents of a string need to be changed frequently, to complete the connection operation of the string two,Common methods of StringBuffer class

No.	Method definition	Type	Describe
1	Public StringBuffer ()	Structure	The construction method of StringBuffer
2	Public StringBuffer append (char c)	Method	A number of append operations are provided in StringBuffer (similar to using "+" in string), and you can append content to StringBuffer, which can add any data type.
3	Public StringBuffer append (String str)	Method
4	Public StringBuffer append (StringBuffer sb)	Method
5	public int indexOf (String str)	Method	Finds whether the specified string exists
6	public int indexOf (String str,int fromIndex)	Method	Finds whether the specified string exists, starting at the specified position
7	Public stringbuffer Insert (int offset,string str)	Method	Adds the specified string at the specified position
8	Public StringBuffer Reverse ()	Method	Invert content to save
9	Public stringbuffer replace (int start,int end,string str)	Method	Specify content Substitution
10	public int Length ()	Method	Find the content length
11	Public StringBuffer Delete (int start,int end)	Method	Delete a string of the specified range
12	Public String substring (int start)	Method	String intercept, specifying the start point
13	Public String substring (int start,int end)	Method	Intercepts a specified range of strings
14	Public String toString ()	Method	Method inherited by the object class to change the content to a string type

Third, the use of the string class

 PackageCom.pb.demo1; Public classStringtest { Public Static voidMain (string[] args) {String str= "To learn java! well"; //length Long () methodThe length of the System.out.println (str+ ") is:" +str.length ()); //convert Case toLowerCase (), toUpperCase ()System.out.println ("Convert to lowercase:" +str.tolowercase ()); System.out.println ("Convert to uppercase:" +str.touppercase ()); //Verify that there is a J character        intIndex=str.indexof ("J"); //return the subscript, no return-1System.out.println (index); //substring characters from 0 to 4 but not with subscript 4System.out.println (str.substring (0, 4)); //from the beginning to the end of the subscript 4System.out.println (Str.substring (4)); //SplitString email= "[email protected]; [Email protected]; [Email protected] "; String [] emaillist=email.split (";"); //iterating through an array         for(String s:emaillist) {System.out.println (s); }    }}

Four, StringBuffer class

 PackageCom.pb.demo1; Public classStringbuffertest { Public Static voidMain (string[] args) {stringbuffer str=NewStringBuffer ("Abc_def_add_zzd"); //find the first occurrence of the position        intIndexfirst=str.indexof ("_"); System.out.println ("Find where _ first appears" +Indexfirst); //Add "A" to the back of the first "_"Str.insert (indexfirst+1, "A");        System.out.println (str); //find the index position of the last occurrence of "_"        intIndexlast=str.lastindexof ("_"); System.out.println ("Find index location of last occurrence _" +indexlast); //Delete Last "_"//Str.deletecharat (indexlast);Str.delete (Indexlast, indexlast+1);        System.out.println (str); System.out.println ("==================="); StringBuffer Email=NewStringBuffer ("[Email protected]"); ////find the index location for "@"        intIndex=email.indexof ("@"); Email.replace (0, index, "Tom");            SYSTEM.OUT.PRINTLN (email); }}

Java starts from zero 30 (string and StringBuffer classes)