String processing: String str = ".....";..
*str.equals (); Compares whether the values of two strings are equal to the underlying data type, and compares two variables to the same address.
equals compares the values of two objects for equality.
*str.length ();//Gets the length of the entire string
Str.trim ();//remove spaces on both sides of the string
Str.charat (int i);//Gets the character on an index value
Str.contains (charsequence s);//Whether to include a string
Str.startswith (String s); Determine whether to start with a string
Str.endswith (String s); Determine whether to end with a string
Replace (char O, char N); Replace all o in the string with n
Replace (charsequence O, charsequence n);//Ibid.
*split (String s); Split string
toUpperCase (); Convert a string to uppercase
toLowerCase (); Convert to lowercase
ValueOf (any args); Gets a string instance of an arbitrary argument
*str.indexof (string s);//The index position at which this string appears for the first time
Str.lastindexof (string s);//Take the index where this string last appears
str.substring (int i);//The index value is the string following the integer argument
str.substring (int A, int b);//Take a string between A and B (not including B)
StringBuffer (with buffers) are used primarily to build strings
*stringbuffer append (char c)//Append
StringBuffer Insert (int offset, string str)//Inserts a string at an index location
StringBuffer deletecharat (int index)
StringBuffer Delete (int start, int end)
StringBuffer replace (int start, int end, String s)
StringBuffer setcharat (int index, char ch)
String toString ()
StringBuffer reverse ()//Invert string
System class
static void exit (int status) exits the currently running Java Virtual machine, 0 indicates normal exit
Static long GC ()//manual start garbage collection mechanism is not recommended to manually call System.GC ();
Objects that are outside the scope of the variable will be retrieved automatically by the garbage collection mechanism to call the Finalize method
Long static Currenttimemillis ()//returns the current system time (in the form of a timestamp)
static void Arraycopy (object src, int srcpos, object dest, int destpos, int length)
Digital Packaging class:
Automatic Packing/Unpacking
*integer.parseint (String s); Convert String to int
Integer.parseint (String s, int radix); Convert other binary strings to int
integer.tobinarystring (int i); Converts an int value into a binary string
integer.tooctalstring (int i); Converts an int to an octal string
integer.tohexstring (int i); Converts an int to a 16-binary string
Java Common API