What are Annotations in Java ?.
Annotations in Java are metadatas that adds information to your code in a formal way so that you can keep track to the information added at a later stage. They provide a Java programmer information which describes the program fully in a sophisticated way. Annotations help us in generating descriptor files and giving us way to write boilerplate code each time.
Annonations in Java have a symbol @ in its syntax declaration. Java contains general purpose built in annotations defined in java.lang package as :
@SuppressWarnings : Generally, it is used when we want compiler to turn off the warnings it is displaying.
Program to demonstrate @SuppressWarning annotation in Java
package com.hubberspot.example; import java.util.Random; import java.util.Scanner; import java.util.Date; import java.util.ArrayList; import java.util.Set; import java.util.List; import java.util.Map; import java.util.HashMap; import java.util.AbstractCollection; import java.util.Arrays; import java.util.Vector; import java.util.TreeSet; //1. unused imports warning suppressed by //@SuppressWarnings("unused") //2. The serializable class SuppressWarningDemo does //not declare a static final serialVersionUID field //of type long warning suppressed by //@SuppressWarnings("serial") @SuppressWarnings({"unused", "serial"}) public class SuppressWarningDemo extends Exception { //3. finally block does not complete normally //warning suppressed by @SuppressWarnings("finally") @SuppressWarnings("finally") public static void main(String[] args) { //4. The constructor Date(int, int, int) is deprecated // warning suppressed by @SuppressWarnings("deprecation") @SuppressWarnings("deprecation") Date date = new Date(2012,8,20); //5. ArrayList is a raw type. References to generic type // ArrayListshould be parameterized warning suppressed // by @SuppressWarnings("rawtypes") @SuppressWarnings("rawtypes") ArrayList list = new ArrayList(); try{ }finally{ return; } } }