JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Program: Write a simple generics class example.


Below example shows how to create a simple generics class. We have created SimpleGeneric class, which accepts single type parameter. Look at the generics class definition, the type parameter should be followed by class name and should contain with in <>, here T defines the type parameter. You can find comments at example itself.


package com.java2novice.generics;

public class MySimpleGenerics {

	public static void main(String a[]){
		
		//we are going to create SimpleGeneric object with String as type parameter
		SimpleGeneric<String> sgs = new SimpleGeneric<String>("JAVA2NOVICE");
		sgs.printType();
		//we are going to create SimpleGeneric object with Boolean as type parameter
		SimpleGeneric<Boolean> sgb = new SimpleGeneric<Boolean>(Boolean.TRUE);
		sgb.printType();
	}
}

/**
 * Here T is a type parameter, and it will be replaced with 
 * actual type when the object got created. 
 */
class SimpleGeneric<T>{
	
	//declaration of object type T
	private T objReff = null;
	
	//constructor to accept type parameter T
	public SimpleGeneric(T param){
		this.objReff = param;
	}
	
	public T getObjReff(){
		return this.objReff;
	}
	
	//this method prints the holding parameter type
	public void printType(){
		System.out.println("Type: "+objReff.getClass().getName());
	}
}

Output:
Type: java.lang.String
Type: java.lang.Boolean
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Java Generics Sample Code Examples

  1. Write a simple generics class example.
  2. Write a simple generics class example with two type parameters.
  3. How implement bounded types (extend superclass) with generics?
  4. How implement bounded types (implements an interface) with generics?
  5. What is generics wildcard arguments? Give an example.
Knowledge Centre
Stream and types of Streams
A Stream is an abstraction that either produces or consumes information. There are two types of Streams and they are:

Byte Streams: Provide a convenient means for handling input and output of bytes. Byte Streams classes are defined by using two abstract classes, namely InputStream and OutputStream.

Character Streams: Provide a convenient means for handling input & output of characters. Character Streams classes are defined by using two abstract classes, namely Reader and Writer.
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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java is registered trademark of Oracle.
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