/*
Common Operations for string:
String str= "ABCHGTHUJIDFG";
1, get
1.1 The string contains the number of characters, which is the length of the string.
int Lenrth ():
Str.length (); Note that the method of getting the length of the string differs from the method of getting the length of the array. Array in format: arr.length
1.2 Gets the character of the position based on the position.
char charAt (int index):
Str.charat (4);
1.3 Gets the position of the character based on the character.
int indexOf (int ch):
Str.indexof (' h ');///Note that the parameter is of type int because ASCII encoding is used, so the character arguments can be passed directly when using the function.
Str.indexof (' a '); Returns the position of a in the string from left to right.
int indexOf (int ch,int fromindex):
Str.indexof (' t ', 2); Returns the position at which the CH appears in the string, starting at the specified position in Fromindex.
int indexOf (String substr):
Str.indexof ("abc");//Returns the position of the substring in the first occurrence of the string. That is the position of a. Returns 1 if it does not exist
int indexOf (String substr,int fromindex):
Str.indexof ("abc", 5);//starting at index position 5, gets the position of ABC in the string.
int lastIndexOf (int ch)://Returns the position of the last occurrence of a character.
2, judging
2.1 Whether a substring is contained in a string.
Boolean contains (str);
2.2 Whether the string has content.
Boolean isEmpty (); The principle is to determine whether the length is zero.
2.3 Whether the string starts with the specified content.
Boolean startsWith (String str);
2.4 Whether the string ends with the specified content.
Boolean endsWith (String str);
2.5 Determines whether the contents of the string are identical, and copies the Equals method in the object class.
Boolean equals (str);
2.6 Determine if the content is the same and ignore the case.
Boolean equalsignorecase ();
3, conversion
3.1 Turning character arrays into strings
Constructor: String (char[])
String (Char[],offset,count)//starts with a number of four characters indexed as offset.
static method: Static String copyvalueof (char[])
Static String copyvalueof (char[] data,int offset,int count)
3.2 Convert a string to a character array
Char[] ToCharArray ();
3.3 Convert a byte array to a string
Constructor: String (byte[])
String (Byte[],offset,count)//starts with a number of four characters indexed as offset.
3.4 Turning a string into a byte array
Byte[] GetBytes ();
3.5 Convert the base data type to a string:
static String valueOf (int)
Static String valueOf (double)
Special: Strings and byte arrays can be specified in the encoding table during the conversion process.
4, replace
String Replace (Oldchar,newchar)
5, cutting
string[] Split (regex) //Note back
Class Stringdemo {public static void main (string[] args) {method_3 ();} public static void Method1 () {string str= "ASBHDJUILDKJUISDF"; SOP ("String length:" +str.length ()); SOP ("character subscript 3:" +str.charat (3 ), SOP ("H first occurrence position subscript:" +str.indexof (' h ')), SOP ("Subscript position is 5" after D's position subscripts: "+str.indexof (' d ', 5)"), SOP ("substring Jui location:" + Str.indexof ("Jui")), SOP ("The last occurrence of D's position subscript:" +str.lastindexof ("D")), SOP ("shows the index of the substring appearing at the far right of the string:" +str.lastindexof ("Jui ", 8)); System.out.println ("Hello world!");} public static void Method2 () {char[] arr={' t ', ' r ', ' E ', ' Q ', ' A ', ' s ', ' d ', ' f '}; String S=new string (arr), SOP ("s=" +s), SOP ("-------------------"); String S1=new string (arr,3,4),//The number of characters starting at index 3, and 4 characters to form a string. SOP ("s1=" +s1); SOP ("-------------------"); String s2= "Hello World"; char[] Chs=s2.tochararray (), for (int i=0;i<chs.length; i++) {SOP ("chs[" +i+ "]=" +chs[i]);} SOP ("-------------------"); String s3=s2.replace (' H ', ' A ');//strong H is replaced by Asop (S3); String s4=s3.replace ("Aello", "Hello,,,,");//replace Aello with Hello,,,, SOP (S4);} public static void Sop (Object obj) {System.out.println (obj);} Public STAtic void Method_split () {String str= "Zhang San & John Doe"; String[] Arr=str.split ("&"); for (int i=0;i<arr.length; i++) {SOP (arr[i]);}} public static void Method_value () {int[] arr={1,2,3,4,5,6,7,8,9};for (int i=0;i<arr.length; i++) {SOP (arr[i]);}} public static void Method_3 () {String str= ' Hello world! SOP (Str.touppercase ()), SOP (Str.tolowercase ()), SOP (Str.trim ()); String str1= "Abcdfa"; String str2= "ABCDF"; Sop (Str1.touppercase (). CompareTo (Str2.touppercase ()));}}
Is the type of the string array.
Set type of array: int[] arr ={1,2,3,4,5,6,7}
Double[] Arr ={1.0,1.2,1.3,1.4,1.5,1.5,1.7}
Byte[] Arr
char[] Arr ={' s ', ' d ', ' f ', ' g ', ' H '}
String[] arr ={"SDF", "FFF", "GGG", "Tgh", "GBF"}
6, SUBSTRING, getting part of a string
string substring (begin);//start from the specified position to the end, and if the corner label does not exist, an exception will occur
String substring (begin,end);//contains header does not contain tail
7, convert, remove spaces, compare
7.1 Convert a string to uppercase or lowercase
String toUpperCase ();
String toLowerCase ();
7.2 Remove multiple spaces at both ends of a string
String trim ();
7.3 Comparison of two strings in natural order
int CompareTo (string);
*/
Java String Class-string common operations
