In Java, @Deprecated is an annotation that helps in informing the compiler that the specific class, method, or field is no longer in use since it is ceased or superseded. Moreover, a warning should be given when anyone tries to use it. The main advantage for deprecation is in the case where any methods are renamed or added, changes occur. Since it may affect the working of the program, deprecated annotation became very useful. Syntax, working, and example of @deprecated annotation will be discussed in the following sections.
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@deprecated can be used in classes, interfaces, method, member variable, constructor, etc. Let us see each of them in detail.
@deprecated interface sample { //methods of the interface .... . }
@deprecated class sample { //implementation of the class sample . . . . . }
@deprecated class sample { @deprecated Public void samplemethod1() { //implementation of the old samplemethod . . . . . } Public void samplemethod2() { //implementation of the newsamplemethod . . . . . } }
class sample { @deprecated //old field Public static final float PI=3.14 // new field Public static final float PI_VALUE=3.14 }
class sample { @deprecated sample(int a, int b, int c) { //implementation of the old constructor . . . . . } sample(intd) { //implementation of the new constructor . . . . . } }
As already discussed, deprecation of a method, field, or class is done by using @deprecated annotation. In addition to that, to notify the developer, the @deprecated java doc tag will be included in the comment section along with the modification.
Below are some of the common contexts where this annotation is used.
Note:
The compiler won’t issue a deprecated warning in the cases such as:
Let us see some of the programs that use deprecated in Java. While writing programs, always make sure that you use @Deprecated for deprecation and @deprecated for documentation purpose.
Uses a deprecated variable name.
Code:
public class depexample { /* @deprecated The field num1 will be replaced by * newnum field */ @Deprecated int num1 = 10; //new field final int newnum = 10; public static void main(String a[]){ //create an object for the class depexample obj = new depexample(); //print num System.out.println(obj.num1); } }
Sample Output
In this program, a variable num1 is deprecated, and a Newnum is also declared to use instead of num1. So, on executing this program, the value 10 gets printed.
Uses a deprecated method name.
Code:
public class depexample { /* @deprecated The function method1 will be replaced by method2 */ @Deprecated //old method public void method1(){ System.out.println("This is a deprecated method"); } //new method public void method2(String m1, String m2){ System.out.println(m1+m2); } public static void main(String a[]){ //class object depexample obj = new depexample(); //call old method obj.method1(); }}
Sample Output
In this program, a method named method1 is deprecated, and another method named method2 is declared to use instead of method1. So, on executing this program, the line gets printed.
Uses a deprecated method name as well as the deprecated variable name.
Code:
public class depexample { /* @deprecated The field num1 will be replaced by * newnum field */ @Deprecated int num1 = 10; //new field final int newnum=10; /* @deprecated The function method1 will be replaced by method2 */ //old method public void method1(){ System.out.println("This is a deprecated method"); } //new method public void method2(String m1, String m2){ System.out.println(m1+m2); } public static void main(String a[]){ //class object depexample obj = new depexample(); //call old method obj.method1(); //print num System.out.println(obj.num1); } }
Sample Output
In this program, the first two programs are combined such that a variable num1 is deprecated, and a Newnum is also declared to use instead of num1. Moreover, a method named method1 is deprecated, and another method named method2 is declared to use instead of method1. So, on executing this program, the value 10 and one line gets printed.
Uses a deprecated constructor as well as the deprecated variable name.
Code:
public class depexample { /* @deprecated The field num1 will be replaced by * newnum field */ @Deprecated int num1=10; //new field final static int newnum=10; /* @deprecated The constructor depexamplewill be replaced by second depexample */ //old constructor depexample(int a, int b, int c){ System.out.println("This is a deprecated method"); } //new constructor depexample(float d, int e, float f){ System.out.println(d+f); } public static void main(String a[]){ //class object depexample obj = new depexample(newnum, newnum, newnum); //print num System.out.println(obj.num1); }}
Sample Output
In this program, a variable num1 is deprecated, and a Newnum is also declared to use instead of num1. Moreover, the constructor declared first is also deprecated, and the second constructor is declared to use instead of the first constructor. So, on executing this program, the value 10 and one line gets printed.
Using this article, you will be able to understand what deprecation is and the different situations where several users can use it. In addition to that, syntax, working, examples of @Deprecated annotation is also discussed, along with working code snippets and sample outputs.
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