Getting started with Java basics to practical applications: How to get started quickly?

Java entry-to-practice guide: including basic syntax introduction (variables, operators, control flow, objects, classes, methods, inheritance, polymorphism, encapsulation), core Java class libraries (exception handling, collections, generics, input /output stream, network programming, date and time API), practical cases (calculator application, including code examples).

Java Basics to Practical Applications: Quick Start Guide

As an object-oriented programming language, Java is famous for its powerful functions and wide range of applications. famous. This article will take you from the basics of Java to practical applications, allowing you to get started quickly and start your Java development journey.

1. Introduction to basic syntax

• Variable types, operators and control flow
• Objects, classes and methods
• Inheritance, polymorphism and Encapsulation

2. Core Java class library

• Exception handling, collections and generics
• Input/output streams and network programming
• Date and time API

3. Practical case: Calculator application

Code example:

public class Calculator {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        System.out.println("Enter the first number:");
        double num1 = input.nextDouble();

        System.out.println("Enter the second number:");
        double num2 = input.nextDouble();

        System.out.println("Select an operation (+, -, *, /):");
        char operator = input.next().charAt(0);

        double result = 0;
        switch (operator) {
            case '+':
                result = num1 + num2;
                break;
            case '-':
                result = num1 - num2;
                break;
            case '*':
                result = num1 * num2;
                break;
            case '/':
                if (num2 == 0) {
                    System.out.println("Division by zero is undefined!");
                } else {
                    result = num1 / num2;
                }
                break;
            default:
                System.out.println("Invalid operation!");
        }

        System.out.println("Result: " + result);
    }
}

Run:

• at Create a new Java project in the IDE and save the code file as Calculator.java.
• Compile and run the application.
• Enter two numbers and an operator and the app will calculate and display the result.

Through this practical case, you can apply the basic knowledge of Java and experience the powerful functions of Java first-hand.

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