Fundamental Java Programming Structures. A Simple Java Program; Comments; Data Types. The main method in Java is. Java Methods - Learn Java in simple and easy. When a program invokes a method. The following program displays all. JAVA: Creating a Simple Class The first section of Java program. However since the EmpDemo class contains the main.
JAVA: Creating a Simple Class. JAVA: Creating a Simple Class. The first section of Java program identifies the environment information. 1.1 Your First Java Program: Hello World. It specifies the classes or packages that will be referred to in the program. This information is specified with the help of the import statement. A program may have more than one import statement. An example of an import statement is: import java. This statement imports the awt package, which is used to create the Graphical User Interface (GUI) objects. Here, java is the name of the folder, which contains the package awt. Therefore, a class declaration follows the import statement. In Java, the whole code, including variable and method declaration, should be included within a class. A single program may have several classes. These classes may be derived from other classes. A semicolon terminates program statement. The program may also include comments as seen in the earlier sessions. The compiler ignores the comments. The structure of a class is: class Classname. In this case the new data type is Employee. A class declaration only creates a template; it does not create an actual object. To create an Employee object, the syntax will be: Employee emp = new Employee (); After this statement is executed, emp will be an instance of Employee. Thus, it will first have a physical existence. Every time an instance of a class is created, an object is created. The Java programming language supports overloading methods, and Java can distinguish between methods with different method signatures.The object contains its own copy of each instance variable defined by the class. Thus every Employee object will have its own copies of instance variables number, name and salary. A dot operator (.) is used to access these variables. The dot operator links the name of the object with the name of an instance variable. For example to assign a value to the salary variable of the emp object the syntax would be: emp. This statement tells the compiler to assign the value of 5. The complete program, illustrating the creation of a simple class is: class Employee. However since the Emp. Demo class contains the main () method, the file should be saved with the name . On compilation two . Employee class and the other for Emp. Demo class. To run the program, one must execute.
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