The automatic boxing and unpacking feature in Java.

1 //automatic boxing and unpacking functionality in Java.2 classautoboxingunboxing3 {4      Public Static voidMain (string[] args)5     {6         //assigns a basic type variable directly to the Interger object. 7Integer inobj = 5;8Object inObj1 = 6;9         //assign a Boolean variable directly to a variable of type object.TenObject boolobj =true; One         //assigning an Integer object directly to the INT type variable A         intit =inobj; -         if(BoolobjinstanceofBoolean) -         { the             Booleanb =(Boolean) boolobj; - System.out.println (b); -         } -  +         if(inObj1instanceofInteger) -         { +             intx =(Integer) inObj1; ASystem.out.println ("x=" +x); at         } -     } -}

1 //the wrapper class implements the conversion between the base type and the string.2 /*3 "1" There are two ways to convert the value of a string type to a value of a base type:4 (1) The parsexxx (String s) static method provided by the wrapper class (this method is provided by all wrapper classes except character). 5 (2) The xxx (String s) constructor provided by the wrapper class. 6 the "2" string class provides multiple (9) overloaded valueof () methods for converting a primitive type variable to a string. 7 If you want to convert a primitive type variable to a string, there is an easier way to do this: set the base type variable and the ""8 for the connection operation, the system automatically converts the basic type variable into a string. 9 */Ten  Public classprimitive2string One { A      Public Static voidMain (string[] args) -     { -         //(1) theString intstr = "123"; -         //converts a specific string into an int variable.  -         intIt1 =Integer.parseint (INTSTR); -         intIt2 =NewInteger (INTSTR); + System.out.println (it2); -  +         //(2) AString floatstr = "4.56"; at         //convert a specific string into a float variable -         floatFT1 =float.parsefloat (FLOATSTR); -         floatFT2 =NewFloat (FLOATSTR); - System.out.println (ft2); -  -  in         //(3) -         //Convert a float variable to a string variable to         floatF1 = 2.345f; +String Ftstr =string.valueof (F1); - System.out.println (FTSTR); the  *         //(4) $         //convert a double variable to a string variablePanax Notoginseng         DoubleD1 = 1.234; -String Dbstr =string.valueof (d1); the System.out.println (DBSTR); +  A         //(5) the         //Convert a Boolean variable to a string variable +         BooleanL =true; -String Boolstr =string.valueof (l); $ System.out.println (Boolstr.touppercase ()); $  -         //(6) -         //The basic type variable is converted to a string type by the join operation. the         intx = 34; -String xx = 34+ "";WuyiSystem.out.println ("This is a string number" +xx); the  -         //the CompareTo () method in the String class WuInteger I1 = 4; -         intX1 = I1.compareto (NewInteger (5)); AboutSystem.out.println ("x=" +x1); $     } -}

The automatic boxing and unpacking feature in Java.