Conditional statements. Java Core

Сентябрь 7, 2022

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Conditional statements. Java Core

Содержание

2. Agenda Operators Conditional statements Enum Comparing objects JUnit Practical tasks
3. Simple Assignment Operator = Simple assignment operator Arithmetic operators Arithmetic Operators + Additive operator (also used
4. Unary Operators Unary Operators + Unary plus; indicates positive value - Unary minus; negates an expression
5. Equality and Relational Operators == Equal to != Not equal to > Greater than >= Greater
6. The && and || operators perform Conditional-AND and Conditional-OR operations on two boolean expressions. && Conditional-AND
7. Ternary Operator ? : condition ? value1 : value2 What are the values of variable str1
8. Statement if if (condition) { then-statement; } if (condition) { then-statement; } else { else-statement; }
9. switch (expression) { case const-expr1 : statement(s); break; case const-expr1 : statement(s); break; default : statement(s);
10. Example BufferedReader br = new BufferedReader( new InputStreamReader(System.in)); System.out.println("Do you enjoy Java? (yes/no/maybe)"); String input =
11. An enum type is a special data type that enables for a variable to be a
12. Season season; ... switch (month) { case "Desember": case "January": case "February": season = Season.WINTER; break;
13. public class Student { private String name; private int age; public Student(String name, int age) {
14. hashCode @Override public int hashCode() { final int prime = 31; int result = 1; result
15. equals @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj ==
16. JUnit Framework JUnit is a unit testing framework for the Java programming language. JUnit has been
17. Testing Problems Programmers should write tests As you probably know programmers always busy, and they have
18. JUnit plugin for Eclipse IDE Mr. Erich Gamma who is a one of developers of JUnit
19. JUnit assertion methods
20. JUnit
21. JUnit
22. public class Calc { public int add(int a, int b) { return a + b; }
23. import static org.junit.Assert.*; import org.junit.Test; public class CalcTest { Calc calc = new Calc(); @Test public
24. Enter three numbers. Find out how many of them are odd. Enter the number of the
25. HomeWork (online course) UDEMY course "Java Tutorial for Complete Beginners": https://www.udemy.com/java-tutorial/ Complete lessons 10, 11, 13:
26. Unit Testing with JUnit Short step-by-step online course: https://www.udemy.com/junit-tutorial-for-beginners-with-java-examples/learn/v4/overview
27. Solve the next tasks: read 3 float numbers and check: are they all belong to the
29. Скачать презентацию

Слайд 2

Agenda
Operators
Conditional statements
Enum
Comparing objects
JUnit
Practical tasks

Слайд 3

Simple Assignment Operator
= Simple assignment operator
Arithmetic operators
Arithmetic Operators
+ Additive operator (also

used for String concatenation)
- Subtraction operator
* Multiplication operator
/ Division operator
% Remainder operator

int x = 11;
int y = 7;
int a = x + y; // a = 18
int s = x - y; // s = 4
int m = x * y; // m = 77
int d = x / y; // d = 1
int r = x % y; // r = 4

Слайд 4

Unary Operators
Unary Operators
+ Unary plus; indicates positive value
- Unary minus; negates an expression
++ Increment

operator; increments a value by 1
-- Decrement operator; decrements a value by 1
! Logical complement operator; inverts the value of a boolean

int x = 5;
int a, b;
a = x++; // a = 5 x = 6
x--; // x = 5
b = ++x; // b = 6 x = 6
++x; // x = 7
boolean bool = true;
// true
System.out.println(bool);
// false
System.out.println(!bool);

Слайд 5

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

to
< Less than
<= Less than or equal to

Equality and Relational Operators

int x = 5;
int y = -5;
System.out.println(x == y); // false
System.out.println(x != y); // true
System.out.println(x >= y); // true

Слайд 6

The && and || operators perform Conditional-AND and Conditional-OR operations on

two boolean expressions.
&& Conditional-AND
|| Conditional-OR

Conditional Operators

score >= 3 && score <= 5
day == "Saturday" || day == "Sunday"

What is the result?
int t = 5, s = 4, v = 7;
System.out.println(t > s && t > v || s < v);
System.out.println((t < v || s > v) && t < s);

Слайд 7

Ternary Operator ? :
condition ? value1 : value2
What are

the values of variable str1 and str2?
int t = 5, s = 4;
String str1 = t >= ++s? "yes" : "no";
int a = 3, b = 2;
String str2 = a-- == b ? "yes" : "no";

Ternary (conditional operator) consists of three operands and is used to evaluate Boolean expressions. The goal of the operator is to decide which value should be assigned to the variable.

Слайд 8

Statement if
if (condition) {
then-statement;
}
if (condition) {

then-statement;
} else {
else-statement;
}

if (temperature<10) {
System.out.println(“It’s too cold”);
} else {
System.out.println(“It’s Ok”); ;
}

The if-then statement tells your program to execute a certain section of code only if a particular test evaluates to true.

Слайд 9

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

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

switch

A switch statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each case.

Слайд 10

Example
BufferedReader br = new BufferedReader(
new InputStreamReader(System.in));
System.out.println("Do you enjoy Java? (yes/no/maybe)");
String

input = br.readLine();
switch (input.toLowerCase()) {
case "yes":
case "maybe":
System.out.println("Great!");
break;
case "no":
System.out.println("Too bad!");
break;
default:
System.out.println("Wrong!");
}

Слайд 11

An enum type is a special data type that enables for a variable

to be a set of predefined constants. The variable must be equal to one of the values that have been predefined for it.
public enum Season {
WINTER, SPRING, SUMMER, AUTUMN
}
Season season;
season = Season.WINTER;

Enum

Слайд 12

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);
}

Example

Слайд 13

public class Student {
private String name;
private int age;
public Student(String name, int

age) {
this.name = name;
this.age = age;
}
getters, setters ...
}

Comparing objects

Which will be the results?
Student student1 = new Student("Ira", 25);
Student student2 = new Student("Ira", 25);
System.out.println(student1 == student2);
System.out.println(student1.equals(student2));

Слайд 14

hashCode
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result

= prime * result + age;
result = prime * result
+ ((name == null) ? 0 : name.hashCode());
return result;
}

Слайд 15

equals
@Override
public boolean equals(Object obj) {
if (this == obj) return true;
if (obj

== null) return false;
if (getClass() != obj.getClass()) return false;
Student other = (Student) obj;
if (age != other.age) return false;
if (name == null) {
if (other.name != null) return false;
} else if (!name.equals(other.name)) return false;
return true;
}

Слайд 16

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.

Слайд 17

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

Слайд 18

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

Слайд 19

JUnit assertion methods

Слайд 20

JUnit

Слайд 21

JUnit

Слайд 22

public class Calc {
public int add(int a, int b) {
return

a + b;
}
public int div(int a, int b){
return a / b;
}
}

Class Calc

Слайд 23

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);
}
}

Class CalcTest

Слайд 24

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.

Practical tasks

Слайд 25

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

10, 11, 13:

Слайд 26

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

Слайд 27

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

Homework

Conditional statements. Java Core

Содержание

AgendaOperatorsConditional statementsEnumComparing objectsJUnitPractical tasks

Simple Assignment Operator= Simple assignment operatorArithmetic operatorsArithmetic Operators+ Additive operator (also

Unary OperatorsUnary Operators+ Unary plus; indicates positive value- Unary minus; negates an expression++ Increment

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

The && and || operators perform Conditional-AND and Conditional-OR operations on

Ternary Operator ? : condition ? value1 : value2 What are

Statement ifif (condition) { then-statement; } if (condition) {

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

ExampleBufferedReader br = new BufferedReader( new InputStreamReader(System.in));System.out.println("Do you enjoy Java? (yes/no/maybe)");String

An enum type is a special data type that enables for a variable

Season season;...switch (month) {case "Desember": case "January": case "February": season = Season.WINTER;

public class Student { private String name; private int age; public Student(String name, int

hashCode@Override public int hashCode() { final int prime = 31; int result = 1; result

equals@Overridepublic boolean equals(Object obj) { if (this == obj) return true; if (obj

JUnit FrameworkJUnit is a unit testing framework for the Java programming

Testing ProblemsProgrammers should write testsAs you probably know programmers always busy,

JUnit plugin for Eclipse IDEMr. Erich Gamma who is a one

JUnit assertion methods

JUnit

JUnit

public class Calc {public int add(int a, int b) { return

import static org.junit.Assert.*;import org.junit.Test;public class CalcTest { Calc calc = new

Enter three numbers. Find out how many of them are odd.Enter

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

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

Solve the next tasks:read 3 float numbers and check: are they

Похожие презентации

Agenda
Operators
Conditional statements
Enum
Comparing objects
JUnit
Practical tasks

Simple Assignment Operator
= Simple assignment operator
Arithmetic operators
Arithmetic Operators
+ Additive operator (also

Unary Operators
Unary Operators
+ Unary plus; indicates positive value
- Unary minus; negates an expression
++ Increment

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

Ternary Operator ? :
condition ? value1 : value2
What are

Statement if
if (condition) {
then-statement;
}
if (condition) {

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

Example
BufferedReader br = new BufferedReader(
new InputStreamReader(System.in));
System.out.println("Do you enjoy Java? (yes/no/maybe)");
String

Season season;
...
switch (month) {
case "Desember": case "January": case "February":
season = Season.WINTER;

public class Student {
private String name;
private int age;
public Student(String name, int

hashCode
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result

equals
@Override
public boolean equals(Object obj) {
if (this == obj) return true;
if (obj

JUnit Framework
JUnit is a unit testing framework for the Java programming

Testing Problems
Programmers should write tests
As you probably know programmers always busy,

JUnit plugin for Eclipse IDE
Mr. Erich Gamma who is a one

public class Calc {
public int add(int a, int b) {
return

import static org.junit.Assert.*;
import org.junit.Test;
public class CalcTest {
Calc calc = new

Enter three numbers. Find out how many of them are odd.
Enter

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

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

Solve the next tasks:
read 3 float numbers and check: are they