Packaging box-packing and unpacking-in-process conversion

Introduction

Basic data type Object wrapper class
byte byte
 Short Short
int IntegerInteger.max_value
Long Long
Float Float
Double Double
Char Character
Boolean Boolean

Auto boxing, automatic unpacking

  
    Integer i = 4; //Auto-boxing, automatically converted to the following form: integer i = new integer (4);  i + = 6; //auto-unpacking int, then automatically boxed to integer  System.out.println (i); //10. Note that I is still an integer, equivalent to System.out.println (i.ToString ()); 

is equal

   System.out.println (new integer) = = new integer (128)); //false System.out.println (new integer (127) = = new integer (127)); //false System.out.println ("*****************************************");
Integer c1 = 128; //equivalent to Integer c1 =new integer (+); Integer c2 = n;System.out.println (C1 = = C2); //false Integer d1 = 127;Integer d2 = 127;System.out.println (D1 = = D2); //true, if the auto-boxed is "one byte", then the object will be shared and will not be recreated 
   System.out.println ("*****************************************");int e1 = 127; Integer e2 = 127;System.out.println (e1 = = E2); //true System.out.println (e1 = = new Integer (127)); //true System.out.println (e2 = = new Integer (127)); //false 

basic types and strings are swapped with each other

   //Basic Type---> stringSYSTEM.OUT.PRINTLN (123 + 1 + ""); //124 System.out.println ("" + 123 + 1); //1231 System.out.println (integer.tostring (123) + 1); //1231 System.out.println (string.valueof (123) + 1); //1231 System.out.println ("******************************************");//String---> Basic typeSystem.out.println (new Integer (123) + 1); //124, first automatic unpacking, after automatic packing System.out.println (new Integer ("123") + 1); //124 System.out.println (Integer.parseint ("123") + 1); //124 System.out.println (new Integer ("123"). Intvalue ()); //123 System.out.println (new Integer (123). Intvalue ()); //123 

Binary Conversion

   //Decimal ---Other binarySystem.out.println (integer.tobinarystring (16)); //2, 10000 System.out.println (integer.tooctalstring (16)); //8 system, System.out.println (integer.tohexstring (16)); //16 System, ten System.out.println (Integer.tostring (16, 2)); //Can be converted to any binary , 10000System.out.println ("*******************************************");//A binary string--and decimal numberSystem.out.println (Integer.parseint (" -06")); //-6, converts a decimal string to a decimal number System.out.println (Integer.parseint (" -10", 2)); //-2, converting a binary string to a decimal number System.out.println (Integer.parseint (" -10", 16)); //-16, converts a 16 binary string to a decimal number 

From for notes (Wiz)

Packaging box-packing and unpacking-in-process conversion