Suppose there is spell mistake in the method name such as the name is changed from toString to toStrimg. Then on compiling the code will generate the message like this:
Compiling 1 source file to D:tempNew Folder
(2)
TestJavaApplication1buildclasses
D:tempNew Folder
(2)TestJavaApplication1srctest
myannotationTest_Override.java:24: method
does not override a method from its
superclass
@Override
1 error
BUILD FAILED (total time: 0 seconds)

2) Deprecated annotation:
These types of annotations ensure that the compiler warns you when you use the deprecated element of the program. The example given below illustrates this concept. Example: Lets first create the class containing
the deprecated method.

public class Deprecated_method{
@Deprecated
public void showSomething() {
System.out.println(“Method has been
depricated’”);
}
}

Now lets try to invoke this method from inside the other class:

public class Test_Deprication {
public static void main(String arg[]) throws
Exception {
new Test_Deprication();
}
public Test_Deprication() {
Deprecated_method d = new
Deprecated_method();
d.showSomething();
}

The method showSomething() in the above example is declared as the deprecated method. That means we can’t further use this

method any more. On compiling the class Depricated_method does not generate any error. While compiling the class Test_Deprication generates the message like this:
Compiling 1 source file to D:tempNew Folder
(2)TestJavaApplication1buildclasses
D:tempNew Folder
(2)TestJavaApplication1srctestmyannotation
Test_Deprication.java:27:
warning: [deprecation] showSomething() in
test.myannotation.Deprecated_method has
been deprecated
d.showSomething();
1 warning

3) Suppresswarning annotation:

These types of annotations ensure that the compiler will shield the warning message in the annotated elements and also in all of its subelements. Lets take an example:

Suppose you annotate a class to suppress a warning and one of its method to suppress another warning, then both the warning will be suppressed at the method level only. Lets demonstrate it by an example:

public class Test_Depricated {
public static void main(String arg[]) throws
Exception {
new TestDepricated().showSomething();
}
@SuppressWarnings({“deprecation”})
public void showSomething() {
Deprecation_method d = new
Deprecation_method();
d.showSomething();
}
}

This example is suppressing the deprecation warnings that means we can’t see the warnings any more.

Note: Applying annotation at most deeply nested elements is a good idea. It is better to apply annotations at the method level rather than the class to annotate a particular method.