13. interfaces
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An interface in Java is a reference type that defines a contract that can be implemented by classes. It contains only method signatures and constant fields. When a class implements an interface, it inherits the abstract methods and agrees to provide method bodies. Interfaces cannot be instantiated or contain constructors, only classes can be instantiated to implement the behaviors defined in an interface. A class uses the implements keyword to implement one or more interfaces and provide definitions for all of the interface's abstract methods.
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Variables are reserved memory locations that can store values based on their data type. There are two main types of variables in Java: primitive and reference. The eight primitive data types are byte, short, int, long, float, double, boolean and char. Each has a specific size and range of values it can hold. Variables must follow naming conventions like being meaningful and avoiding reserved words. Primitive types like int and double are commonly used for numeric values while boolean and char are used for true/false and character values respectively. Reference types represent objects and will be covered separately.
4. mathematics for computing
This document provides an overview of binary numbers and related concepts in computing:
- Binary numbers are made up of 0s and 1s and have a base-2 value. Mixed binary numbers like 10.1 represent decimals.
- A bit is a single binary digit, and bytes group together 8 bits. File sizes are measured in bytes, kilobytes, megabytes, and larger units.
- Converting between binary and decimal involves placing the binary digits in powers of two and adding them up. Several exercises are provided to practice conversions.
- Fractional binary numbers represent decimals the same way.
- Two's complement is a common way computers represent negative integers in binary by inverting and adding one to the positive
3. introduction to java
Java is a programming language and computing platform originally developed by Sun Microsystems. It was first released in 1995. Key aspects of Java include its APIs, JVM, JRE, and JDK. The JVM is an abstract machine that enables computers to run Java programs. The JRE provides the runtime environment including libraries and files needed to run Java programs. The JDK includes the JVM plus tools like a compiler and documentation generator used for developing Java programs.
2. data structures & algorithms
This document discusses data structures and algorithms and their importance for computer programs. It defines a computer program as a sequence of instructions to automate tasks or solve problems. Good programs should run correctly, efficiently, and be easy to read, debug, and modify. It states that algorithms and data structures together create programs and are used to model real-world data and problems from storage of patient information to transportation networks. Data structures are described as arrangements of data in memory to organize it efficiently, while algorithms manipulate data in data structures to accomplish tasks through a sequence of instructions.
1. introduction mathematics for computing and object oriented programming
This document provides an overview of mathematics for computing and object oriented programming. It discusses the goals of good computer programs and software designs. It then covers key aspects of programming like characteristics of good programs, the software development process, software design, and object oriented programming concepts. Finally, it lists important links and resources for further learning.
Gis for healthcare introduction
This document provides an overview of geographic information systems (GIS) and how they can be used in healthcare. It discusses key concepts in GIS including geography, spatial data and GIS software. It also covers global and regional satellite navigation systems, coordinate systems, map projections, geodetic systems and how mapping has historically been used in public health to study disease transmission and outbreaks. The document promotes the use of open-source GIS software like QGIS for health applications.
Open hospital management information system
A Brief Presentation on the Opensource Hospital Information Management System for the Private Sector healthcare Institutions of Sri Lanka.
Who am i and what i have done
This document provides a summary of Dr. MHB Ariyaratne's qualifications and experience. It outlines that he has an MBBS, MSc, and MD, and has experience as both a medical doctor and software developer, having designed and managed several open source medical applications. It also notes his experience includes tutoring in laboratory informatics and medical logistics. The document then provides details on his work history and roles in obstetrics, radiology, and other medical fields from 2002 to the present, as well as experience as a medical administrator and developer of various health information systems using technologies like JavaEE and C#.
Electronic health record system for sri lankan general practitioners
This is about an Electronic Medical Record System for General Practitioners, especially for those who are from developing countries like Sri Lanka. Details are there in www.lakmedi.com
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13. interfaces
- 1. Interfaces Dr. M H B Ariyaratne buddhika.ari@gmail.com https://goo.gl/LtuPma
- 2. What is an interface? ● A reference type in Java ● Bit like a class, except it can only contain method signatures (abstract methods) and fields ● When a class implements an interface, thereby inheriting the abstract methods of the interface. ● Also contain constants, default methods, static methods, and nested types ● Method bodies exist only for default methods and static methods ● Contains behaviours that a class implements. ● Unless the class that implements the interface is abstract, all the methods of the interface need to be defined in the class
- 3. Similarities to a class ● Can contain any number of methods ● Written in a file with a .java extension, with the name of the interface matching the name of the file. ● The byte code of an interface appears in a .class file ● Interfaces appear in packages, and their corresponding bytecode file must be in a directory structure that matches the package name
- 4. Differ from a class Cannot instantiate an interface Does not contain any constructors All of the methods in an interface are abstract Cannot contain instance fields. The only fields that can appear in an interface must be declared both static and final Not extended by a class; it is implemented by a class An interface can extend multiple interfaces
- 5. Declaring Interfaces ● The interface keyword is used to declare an interface ● An interface is implicitly abstract. You do not need to use the abstract keyword while declaring an interface. ● Each method in an interface is also implicitly abstract, so the abstract keyword is not needed. ● Methods in an interface are implicitly public
- 6. Implementing Interfaces When a class implements an interface, we can think of the class as signing a contract, agreeing to perform the specific behaviors of the interface. If a class does not perform all the behaviors of the interface, the class must declare itself as abstract. A class uses the implements keyword to implement an interface. The implements keyword appears in the class declaration following the extends portion of the declaration.
- 7. Thank you