Java Reference types

  • To create new data types, complex data types, containing simple primitives or other complex data types you must create a class.
  • Reference type can refer to a created object out of a such class or can refer to an array object containing many elements of the same type.
  • They are called reference types because they "refers to" data type that is often large.
    Java Reference example:
    ...
    Foo myFoo = new Foo( );    // The new keyword creates a object of class type Foo 
                               // myFoo is a reference-type variable that holds a 
                               // reference to the newly constructed Foo object
    Foo anotherFoo = myFoo;    // There are now two identical references: 
                               // "myFoo" and "anotherFoo"
    
    int i=20;
                              // In this case method1 and method2 are defined 
                              // in the Foo class
    myFoo.method1( myFoo );   // Object (myFoo) are always  passed to 
                              // methods by reference
    myFoo.method2( i );       // Primitive are passed to methods by values
    ...
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