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Java Class class getTypeParameters() method with example

Class class getTypeParameters() method: Here, we are going to learn about the getTypeParameters() method of Class class with its syntax and example.
Submitted by Preeti Jain, on November 23, 2019

Class class getTypeParameters() method

• getTypeParameters() method is available in java.lang package.
• getTypeParameters() method is used to return an array of TypeVariable that denotes the variable type declared by the generic representation of this GenericDeclaration.
• getTypeParameters() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• getTypeParameters() method may throw an exception at the time of returning parameter types.
  GenericSignatureFormatError: This exception may raise when the generic signature of this generic declaration does not match to the format given in the JVM Specification.

Syntax:

    public TypeVariable[] getTypeParameters();

Parameter(s):

• It does not accept any parameter.

Return value:

The return type of this method is TypeVariable[], it returns the following value based on the given cases,

• It returns an array of TypeVariable that denotes the variable type defined by the generic declaration.
• It returns 0, when the underlying generic declaration defines no variable type.

Example:

// Java program to demonstrate the example 
// of TypeVariable[]  getTypeParameters () method of Class 

import java.util.*;
import java.lang.reflect.*;

public class GetTypeParametersOfClass {
 public static void main(String[] args) throws Exception {
  // It returns the array of TypeVariable represented by the 
  //class ArrayList
  TypeVariable[] type_var = ArrayList.class.getTypeParameters();

  for (int i = 0; i < type_var.length; ++i) {
   System.out.print("TypeVariable of ArrayList: " + " ");
   System.out.println(type_var[i].getName());
  }
 }
}

Output

TypeVariable of ArrayList:  E