Wrapper class in JavaWrapper class in java are the Object representation of eight primitive types in java. All the wrapper classes in java are immutable and final.Java 5 autoboxing and unboxing allows easy conversion between primitive types and their corresponding wrapper classes in java programs.Below table shows the primitive types and their wrapper class in java.Primitive type Wrapper class Constructor Argumentsbyte Byte byte or Stringshort Short short or Stringint Integer int or Stringlong Long long or Stringfloat Float float, double or Stringdouble Double double or Stringchar Character charboolean Boolean boolean or StringWhy do we need wrapper classes?I think it was a smart decision to keep primitive types and Wrapper classes separate to keep things simple. We need wrapper classes when we need a type that will fit in the Object-Oriented Programming like Collection classes. We use primitive types when we want things to be simple. package com.mapack.mk;import java.util.ArrayList;import java.util.List;WrapperClasses.java Examples : public class WrapperClasses { private static void doSomething(Object obj){ } public static void main(String args[]){ int i = 10; char c = 'a'; //primitives are simple to use int j = i 3; //polymorphism achieved by Wrapper classes, we can't pass primitive here doSomething(new Character(c)); List list = new ArrayList(); //wrapper classes can be used in Collections Integer in = new Integer(i); list.add(in); //autoboxing takes care of primitive to wrapper class conversion list.add(j); //wrapper classes can be null in = null; }}

Question

Wrapper class in JavaWrapper class in java are the Object representation of eight primitive types in java. All the wrapper classes in java are immutable and final.Java 5 autoboxing and unboxing allows easy conversion between primitive types and their corresponding wrapper classes in java programs.Below table shows the primitive types and their wrapper class in java.Primitive type     Wrapper class     Constructor Argumentsbyte                         Byte                       byte or Stringshort                       Short                     short or Stringint                             Integer                  int or Stringlong                          Long                      long or Stringfloat                          Float                     float, double or Stringdouble                      Double                 double or Stringchar                          Character           charboolean                   Boolean               boolean or StringWhy do we need wrapper classes?I think it was a smart decision to keep primitive types and Wrapper classes separate to keep things simple. We need wrapper classes when we need a type that will fit in the Object-Oriented Programming like Collection classes. We use primitive types when we want things to be simple. package com.mapack.mk;import java.util.ArrayList;import java.util.List;WrapperClasses.java Examples : public class WrapperClasses {    private static void doSomething(Object obj){            }        public static void main(String args[]){        int i = 10;        char c = 'a';                //primitives are simple to use        int j = i 3;                //polymorphism achieved by Wrapper classes, we can't pass primitive here        doSomething(new Character(c));                List list = new ArrayList();        //wrapper classes can be used in Collections        Integer in = new Integer(i);        list.add(in);                //autoboxing takes care of primitive to wrapper class conversion        list.add(j);                //wrapper classes can be null        in = null;    }}

Mukesh Kumar · Accepted Answer

Wrapper class in JavaWrapper class in java are the Object representation of eight primitive types in java. All the wrapper classes in java are immutable and final.Java 5 autoboxing and unboxing allows easy conversion between primitive types and their corresponding wrapper classes in java programs.Below table shows the primitive types and their wrapper class in java.Primitive type     Wrapper class     Constructor Argumentsbyte                         Byte                       byte or Stringshort                       Short                     short or Stringint                             Integer                  int or Stringlong                          Long                      long or Stringfloat                          Float                     float, double or Stringdouble                      Double                 double or Stringchar                          Character           charboolean                   Boolean               boolean or StringWhy do we need wrapper classes?I think it was a smart decision to keep primitive types and Wrapper classes separate to keep things simple. We need wrapper classes when we need a type that will fit in the Object-Oriented Programming like Collection classes. We use primitive types when we want things to be simple. package com.mapack.mk;import java.util.ArrayList;import java.util.List;WrapperClasses.java Examples : public class WrapperClasses {    private static void doSomething(Object obj){            }        public static void main(String args[]){        int i = 10;        char c = 'a';                //primitives are simple to use        int j = i 3;                //polymorphism achieved by Wrapper classes, we can't pass primitive here        doSomething(new Character(c));                List list = new ArrayList();        //wrapper classes can be used in Collections        Integer in = new Integer(i);        list.add(in);                //autoboxing takes care of primitive to wrapper class conversion        list.add(j);                //wrapper classes can be null        in = null;    }}

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