Saturday, December 24, 2016

How to Install JAVA Part-2

4. Save JAVA File:

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To save JAVA File, we have to use following conditions:

A. If the present java file contains any public element [class, interface, abstract class, enum] then the present JAVA file must be saved with public element name only, if we violate this condition then compiler will rise an error.

B. If no pubic element is existed in present JAVA file then it is possible to save JAVA file with any name like abc.java or xyz.java, but it is suggestible to save JAVA file with main class name instead of any other name.

EX: File Name: abc.java
--------------------------------
class FirstApp {
            public static void main(String[] args) {
                        System.out.println(“First JAVA Application”);
            }
}
Status: No compilation error, but not suggestible to save abc.java


EX: File Name: FirstApp.java
class FirstApp {
            public static void main(String[] args){
                        System.out.println("First JAVA Application");
            }
}
Status: No compilation Error & Suggestible.


EX: File Name: FirstApp.java
public class A {
}
class FirstApp {
            public static void main(String[] args){
                        System.out.println("First JAVA Application");
            }
}
Status: Compilation Error


EX: File Name: A.java
public class A {
}
class FirstApp {
            public static void main(String[] args){
                        System.out.println("First JAVA Application");
            }
}

Status: No Compilation Error.

Q. Is it possible to provide more than one public class with in a single java file?
ANS. No, it is not possible to provide more than one public class with in a single JAVA file, because, if we provide more than  one public class with in a single JAVA file, then we must save that java file with more than one name, which is not possible in OS.

EX: File Name: A.java
public class A {
}
public class B {
}
class FirstApp {
            public static void main(String[] args){
                        System.out.println("First JAVA Application");
            }
}
Status: compilation Error.


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