Use the instanceof operator with a generic class hierarchy.

   
/*
Java 2, v5.0 (Tiger) New Features
by Herbert Schildt
ISBN: 0072258543
Publisher: McGraw-Hill/Osborne, 2004
*/

class Gen<T> {   
  T ob;  
     
  Gen(T o) {   
    ob = o;   
  }   
   
  // Return ob.   
  T getob() {   
    return ob;   
  }   
}   
  
// A subclass of Gen.  
class Gen2<T> extends Gen<T> {  
  Gen2(T o) {  
    super(o);  
  }  
}  
  
 // Demonstrate runtime type ID implications of generic class hierarchy.  
public class HierDemo3 {   
  public static void main(String args[]) {   
     
    // Create a Gen object for Integers.  
    Gen<Integer> iOb = new Gen<Integer>(88);  
  
    // Create a Gen2 object for Integers.  
    Gen2<Integer> iOb2 = new Gen2<Integer>(99);   
    
    // Create a Gen2 object for Strings.  
    Gen2<String> strOb2 = new Gen2<String>("Generics Test");   
  
    // See if iOb2 is some form of Gen2. 
    if(iOb2 instanceof Gen2<?>)   
      System.out.println("iOb2 is instance of Gen2");  
 
    // See if iOb2 is some form of Gen. 
    if(iOb2 instanceof Gen<?>)   
      System.out.println("iOb2 is instance of Gen");  
  
    System.out.println();  
  
    // See if strOb2 is a Gen2. 
    if(strOb2 instanceof Gen2<?>)   
      System.out.println("strOb is instance of Gen2");  
  
    // See if strOb2 is a Gen. 
    if(strOb2 instanceof Gen<?>)   
      System.out.println("strOb is instance of Gen");  
 
    System.out.println();  
  
    // See if iOb is an instance of Gen2, which its not. 
    if(iOb instanceof Gen2<?>)   
      System.out.println("iOb is instance of Gen2");  
  
    // See if iOb is an instance of Gen, which it is. 
    if(iOb instanceof Gen<?>)   
      System.out.println("iOb is instance of Gen");  
  
    // The following can't be compiled because  
    // generic type info does not exist at runtime. 
//    if(iOb2 instanceof Gen2<Integer>)   
//      System.out.println("iOb2 is instance of Gen2<Integer>");  
  }   
}

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2.	Demonstrate the non generic class
3.	Stats attempts (unsuccessfully) to create a generic class
4.	A simple generic class hierarchy.
5.	A nongeneric class can be the superclass of a generic subclass.
6.	Java hierarchy generic class
7.	Custom Generic Object Tester
8.	Pair of template arguments
9.	Generic pair structure
10.	Simple STL Pair Implementation

Use the instanceof operator with a generic class hierarchy. : Generic Class « Generics « Java

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