Generic Method and Class

Lab Objective: In this lab, we will demonstrate a generic method and class. By the end of this lab, learners will be able to utilize the generic method and class.

Java Generics Method

We can create a method that can be used with any type of data. That method is known as the Generics Method.

Create a class named DemoClass. As shown below, we will create a generic method in this class:

Public class DemoClass {

  // create a generics method
  public <T> void genericsMethod(T data) {
    System.out.println("Generics Method:");
    System.out.println("Data Passed: " + data);
  }
}

Create a class named myRunner. In this class, we will invoke the generic method.

public class myRunner {
   public static void main(String[] args) {
    // initialize the class with Integer data
    DemoClass dObj = new DemoClass();
    dObj.genericsMethod(25); // passing int
    dObj.genericsMethod("Per Scholas"); // passing String
    dObj.genericsMethod(2563.5); // passing float
    dObj.genericsMethod('H'); // passing Char
 }
}

Output:

Generics Method:
Data Passed: 25
Generics Method:
Data Passed: Per Scholas
Generics Method:
Data Passed: 2563.5
Generics Method:
Data Passed: H

In the above example, we have created a generic method named genericsMethod.

public <T> void genericMethod(T data) {...}

Here, the type parameter <T> is inserted after the public modifier and before the return type void.

We can call the generics method by placing the actual type <String> and <Integer> inside the bracket before the method name.

Generic Class

A class can have more than one type parameter. In this case, the type parameters are separated by a comma.

For the demonstration, we will initialize two type parameters in the Generic class. The names of the parameter types will be Datatypeone and DatatypeTwo, but these are only names. You are free to use “X” or “Z,” or any other identifier to name parameters.

Create a class named GMultipleDatatype: Write the below code.

public class GMultipleDatatype  <Datatypeone, DatatypeTwo>  {
   Datatypeone valueOne;
   DatatypeTwo valueTwo;

   public GMultipleDatatype(Datatypeone v1, DatatypeTwo v2)
   {
       this.valueOne = v1;
       this.valueTwo = v2;
   }

   public Datatypeone getValueOne() {
       return valueOne;
   }

   public void setValueOne(Datatypeone valueOne) {
       this.valueOne = valueOne;
   }

   public DatatypeTwo getValueTwo() {
       return valueTwo;
   }

   public void setValueTwo(DatatypeTwo valueTwo) {
       this.valueTwo = valueTwo;
   }
}

Create a class named MyRunner as shown below:

public class MyRunner {
   public static void main(String[] args) {
       // initialize generic class
       // with String and Integer data

       GMultipleDatatype<String, Integer> mobj = new GMultipleDatatype("Per Scholas", 11025);

       System.out.println(mobj.getValueOne());
       System.out.println(mobj.getValueTwo());

         // initialize generic class
       // with String and String data
       GMultipleDatatype<String, String> mobj2 = new GMultipleDatatype("Per Scholas", "Non profit");
       System.out.println(mobj2.getValueOne());
       System.out.println(mobj2.getValueTwo());
   }
}

Output:

Per Scholas
11025
Per Scholas
Non profit

1KB

GLAB - 303.11.1 - Generic Method and Class.zip

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