Conditional statements. Java Core презентация

Conditional statements Java Core

Agenda Operators Conditional statements Enum Comparing objects JUnit Practical tasks

Arithmetic operators Simple Assignment Operator = Simple assignment operator

Unary Operators

Equality and Relational Operators Equality and Relational Operators == Equal to != Not equal to > Greater than >= Greater than or equal to < Less than <= Less than or equal to

Conditional Operators The && and || operators perform Conditional-AND and Conditional-OR operations on two boolean expressions. && Conditional-AND || Conditional-OR

Ternary Operator ? :

Statement if

switch switch (expression) { case const-expr1 : statement(s); break; case const-expr1 : statement(s); break; default : statement(s); break; }

Example

Enum

Example Season season; ... switch (month) { case "Desember": case "January": case "February": season = Season.WINTER; break; case "Marth": case "April": case "May": season = Season.SPRING; break; case "June": case "Jule": case "August": season = Season.SUMMER; break; case "September": case "October": case "November": season = Season.AUTUMN; break; default: System.out.println("No this month"); System.exit(0); }

Comparing objects public class Student { private String name; private int age; public Student(String name, int age) { this.name = name; this.age = age; } getters, setters ... }

hashCode

equals

JUnit Framework JUnit is a unit testing framework for the Java programming language. JUnit has been important in the development of test-driven development, and is one of a family of unit testing frameworks collectively known as xUnit that originated with SUnit.

Testing Problems Programmers should write tests As you probably know programmers always busy, and they have no time to write tests They need some tool that can help them Main requirements for this tool: A few lines of code then test should run To write test that won’t run, then write the code that will make run

JUnit plugin for Eclipse IDE Mr. Erich Gamma who is a one of developers of JUnit framework also known as a Eclipse IDE developer JUnit well integrated into Eclipse IDE

JUnit assertion methods

Class Calc public class Calc { public int add(int a, int b) { return a + b; } public int div(int a, int b){ return a / b; } }

Class CalcTest import static org.junit.Assert.*; import org.junit.Test; public class CalcTest { Calc calc = new Calc(); @Test public void testAdd() { assertTrue(calc.add(1, 5) == 6);} @Test public void testDivPositive() { int actual = 4; int expected = calc.div(9, 2); assertEquals(actual, expected); } @Test(expected = Exception.class) public void testDivZero() { int actual = calc.div(23, 0); } }

Practical tasks Enter three numbers. Find out how many of them are odd. Enter the number of the day of the week. Display the name in three languages. Enter the name of the country. Print the name of the continent. (Declare enum with names of continents) Create class Product with fields name, price and quantity. Create four instances of type Product. Display the name and quantity of the most expensive item. Display the name of the items, which has the biggest quantity.

HomeWork (online course) UDEMY course "Java Tutorial for Complete Beginners": https://www.udemy.com/java-tutorial/ Complete lessons 10, 11, 13:

Unit Testing with JUnit Short step-by-step online course: https://www.udemy.com/junit-tutorial-for-beginners-with-java-examples/learn/v4/overview

Homework Solve the next tasks: read 3 float numbers and check: are they all belong to the range [-5,5]; read 3 integer numbers and write max and min of them; read number of HTTP Error (400, 401,402, ...) and write the name of this error (Declare enum HTTPError) Сreate class Dog with fields name, breed, age. Declare enum for field breed. Create 3 instances of type Dog. Check if there is no two dogs with the same name. Display the name and the kind of the oldest dog. *Add Unit Tests to each task, publish code on GitHub

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