The process by which one class acquires the properties(data members) and functionalities(methods) of another class are called inheritance. The aim of inheritance in java is to provide the reusability of code so that a class has to write only the unique features and the rest of the common properties and functionalities can be extended from another class.
The idea behind encapsulation is to hide the implementation details from users. If a data member is private, it can only be accessed within the same class. No outside class can access private data member (variable) of other class.
data structures and abstractions with java 3rd edition pdf free 22
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A class in java is a template that describes the data and behaviour associated with instances of that class. When you instantiate a class you create an object that looks and feels like other instances of the same class. The data associated with a class or object is stored in variables; the behaviour associated with a class or object is implemented with methods.
Dao is a simple java class that contains JDBC logic. The Java Data Access Object (Java DAO) is an important component in business applications. Business applications almost always need access to data from relational or object databases and the Java platform offers many techniques for accessing this data.
Shallow copy in java copies all values and attributes of an object to another object and both objects reference the same memory locations. Deep copy is the creation of an object with the same values and attributes of the object being copied but both objects reference different memory locations.
JDBC stands for Java Database Connector, an API that executes the query to connect with the database. JDBC is a part of Java Standard Edition and uses its drivers to make connectivity with the database. JDBC acts as an abstraction layer that establishes the connection between the Java application and an existing database. The JDBC has four types of drivers:
JPA stands for Java Persistence API is a specification of Java and is used to persist the data between a relational database and the objects of JavJPA is like a connection bridge between relational database systems and object-oriented domain models. As we just discussed, it is only a specification of java, and therefore it is not responsible for performing any operation by itself. To perform an operation, it should be implemented. And to do that, there are some ORM tools such as TopLink, Hibernate, and iBatis that implement JPA for data persistence. The API creates the persistence layer for the web applications and the desktop. Java Persistence API deals with the following services:
Value of final keyword in java which is used with variable, field or parameter once a reference is passed on or instantiation is done it cannot be changed throughout the execution of the program. A variable without any value declared as final is known as a blank or uninitialized final variable. This variable can be only initialized through the constructor.
In some cases, the static method also cannot be overridden because static methods are part of any object other than the class itself. You can also declare a static method with the same signature in the child class but is not considered runtime polymorphism. So, in java static as well as private method overriding is not possible.
Generics allow classes and interfaces to be a type for the definition of new classes in java which enables stronger type checking. It also nullifies the probability of type mismatch of data while insertion.
A vector is an ArrayList-like data structure in java whose size increases as per the demands. Moreover, it also supports some legacy functions not supported by collections. You should also know that a vector is more suitable to work with threads, unlike collection objects.
The basic abstraction of a program running as one or more threads of control in a single flat address space (a Unix process) is the key to the course. Emphasizing that abstraction as the underlying model for understanding how a program works, from both the user program and hardware perspective (with the OS in between), runs as a theme through all topics in the course. Examples include C pointers (to data and functions), function calls and runtime stack management, dynamic memory management in the heap, and the fork/exec system calls.
CS 2112/ENGRD 2112 is an honors version ofCS 2110/ENGRD 2110. Credit is given for only oneof 2110 and 2112. Transfer between 2110 and 2112 (in either direction) isencouraged during the first three weeks. We cover intermediate software design andintroduce some key computer science ideas. The topics are similar to those in2110 but are covered in greater depth with more challenging assignments.Topics include object-oriented programming, program structure andorganization, program reasoning using specifications and invariants, recursion,design patterns, concurrent programming, graphical user interfaces, datastructures, sorting and graph algorithms, asymptotic complexity, and simplealgorithm analysis. Java is the principal programming language.
Java is one of the most widely used object-oriented programming languages, and programming skill in the Java language is in high demand. Nevertheless, this is not a course about Java. Java is simply a good vehicle for explaining many of theideas on data structures, algorithms, and software engineering that will be covered in the course. Most of the ideas you will be exposed to in this course, and the skills you will develop, will transfer to other programming languages.
Specifying a Classpath: Sometimes you may need to inform Java where to find auxiliaryclasses. You can do this with the -cp optionto the java command.Supply a sequence of folders telling Java where to lookfor classes, separated by : (Mac) or; (Windows).
Some Java libraries have been developed for use in CS 2110 and CS 2112 assignments.Feel free to use them.EasyIO: Support for easy console input and output, and for scanninginput from a file or string (like java.util.Scanner, but more powerful).[ doc jar source ]
Here we made a small error in use1 that will lead to corrupted data or a crash.The (pointer, count)-style interface leaves increment1() with no realistic way of defending itself against out-of-range errors.If we could check subscripts for out of range access, then the error would not be discovered until p[10] was accessed.We could check earlier and improve the code:
The standards library and the GSL are examples of this philosophy.For example, instead of messing with the arrays, unions, cast, tricky lifetime issues, gsl::owner, etc.,that are needed to implement key abstractions, such as vector, span, lock_guard, and future, we use the librariesdesigned and implemented by people with more time and expertise than we usually have.Similarly, we can and should design and implement more specialized libraries, rather than leaving the users (often ourselves)with the challenge of repeatedly getting low-level code well.This is a variant of the subset of superset principle that underlies these guidelines.
Large functions are hard to read, more likely to contain complex code, and more likely to have variables in larger than minimal scopes.Functions with complex control structures are more likely to be long and more likely to hide logical errors
If a class has any private data, a user cannot completely initialize an object without the use of a constructor.Hence, the class definer will provide a constructor and must specify its meaning.This effectively means the definer need to define an invariant.
There is nothing wrong with this code as far as the C++ language rules are concerned,but nearly everything is wrong from a design perspective.The private data is hidden far from the public data.The data is split in different parts of the class declaration.Different parts of the data have different access.All of this decreases readability and complicates maintenance.
There is often a choice between offering common functionality as (implemented) base class functions and freestanding functions(in an implementation namespace).Base classes give a shorter notation and easier access to shared data (in the base)at the cost of the functionality being available only to users of the hierarchy.
protected data is a source of complexity and errors.protected data complicates the statement of invariants.protected data inherently violates the guidance against putting data in base classes, which usually leads to having to deal with virtual inheritance as well.
Protected data often looks tempting to enable arbitrary improvements through derivation.Often, what you get is unprincipled changes and errors.Prefer private data with a well-specified and enforced invariant.Alternative, and often better, keep data out of any class used as an interface.
Use gsl::span instead.Pointers should only refer to single objects.Pointer arithmetic is fragile and easy to get wrong, the source of many, many bad bugs and security violations.span is a bounds-checked, safe type for accessing arrays of data.Access into an array with known bounds using a constant as a subscript can be validated by the compiler.
Subscripting with a variable is difficult for both tools and humans to validate as safe.span is a run-time bounds-checked, safe type for accessing arrays of data.at() is another alternative that ensures single accesses are bounds-checked.If iterators are needed to access an array, use the iterators from a span constructed over the array.
In a nutshell, if two threads can access the same object concurrently (without synchronization), and at least one is a writer (performing a non-const operation), you have a data race.For further information of how to use synchronization well to eliminate data races, please consult a good book about concurrency (See Carefully study the literature).
Without those consts, we would have to review every asynchronously invoked function for potential data races on surface_readings.Making surface_readings be const (with respect to this function) allow reasoning using only the function body. 2ff7e9595c
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