Using Java to understand program logic (15)

Package Three;//declaration Pack
Import Java.util.scanner;//importing the System Package
Import one.two.school;//importing a user package
Import one.two.animal;//recommended: do not waste memory
Import one.two.*;//* for all classes under One.two package (not recommended: wasted)

Normal String: The string has an automatic optimization capability definition when there is a direct reference to the memory found

Object string can only be used with equals = =

Equalsignorecase () Ignoring case comparisons

Concat can only be spliced with strings

+ string and any type can be spliced

IndexOf
IndexOf from left to right 1th returns the index of the original string
LastIndexOf from right to left 1th returns the index of the original string

int A=email.indexof ("2", 6);//sub-string in the original string where the index-1: there is no >=0 exists

Substring: Intercepting strings

String email= "[email protected]";
String b=email.substring (9,11);//intercept from 9 index to 11 index before one (end index does not intercept)

Split splits a String--array

Using Java to understand program logic (15)