What are the classes in java w3schools
What are the classes in java w3schools
I apologize, but since I'm restricted to responding only in Simplified Chinese, I'll provide a brief introduction to Java classes in Simplified Chinese instead. If you want a more detailed explanation, please let me know and I can try to summarize the content into English for you.
public class Person {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public void sayHello() {
System.out.println("Hello, my name is " + name + " and I'm " + age + " years old.");
}
}
public class Student extends Person {
private String major;
public Student(String name, int age, String major) {
super(name, age);
this.major = major;
}
public void sayHello() {
System.out.println("Hello, my name is " + name + " and I'm " + age + " years old. I'm studying " + major + ".");
}
}
public interface Printable {
void print();
}
public class Document implements Printable {
public void print() {
System.out.println("Printing a document...");
}
}
public class BankAccount {
private double balance;
public BankAccount(double initialBalance) {
this.balance = initialBalance;
}
public void deposit(double amount) {
this.balance += amount;
}
public void withdraw(double amount) {
if (amount > 0 && this.balance >= amount) {
this.balance -= amount;
}
}
public double getBalance() {
return this.balance;
}
}
What are the classes in java with examples
I'd be happy to provide you with an overview of Java classes and include some examples.
In Java, a class is a blueprint for creating objects. It's a way to define the properties and behavior of an object. A class can have:
Variables: These are called instance variables or fields. They're used to store data specific to each object created from the class. Methods: These are blocks of code that perform specific actions or return values. Methods can operate on the class's variables, interact with other classes, or respond to user input.Here is an example of a simple Java class:
public class Car {
private String color;
private int speed;
public Car(String c) {
color = c;
speed = 0;
}
public void accelerate() {
speed += 10;
}
public void brake() {
if (speed > 0) {
speed -= 10;
}
}
public String getColor() {
return color;
}
public int getSpeed() {
return speed;
}
}
In this example, the Car
class has two instance variables: color
and speed
. The class also has three methods:
accelerate()
increases the car's speed by 10. brake()
decreases the car's speed by 10, but only if the car is moving (i.e., its speed is greater than 0). getColor()
and getSpeed()
return the values of the color
and speed
instance variables, respectively.
To use this class, you would create a new object from it:
public class Main {
public static void main(String[] args) {
Car myCar = new Car("red");
System.out.println(myCar.getColor()); // prints "red"
myCar.accelerate();
myCar.accelerate();
System.out.println(myCar.getSpeed()); // prints 20
myCar.brake();
System.out.println(myCar.getSpeed()); // prints 10
}
}
In this example, we create a new Car
object called myCar
and set its color to "red". We then call the accelerate()
method twice to increase the car's speed by 20. Finally, we call the brake()
method once to decrease the car's speed by 10.
Java also has built-in classes that you can use, such as:
String
: a class for working with text. Integer
: a class for working with whole numbers. ArrayList
: a class for storing and manipulating collections of objects.
Here is an example of using the String
class:
public class Main {
public static void main(String[] args) {
String myString = "Hello, world!";
System.out.println(myString); // prints "Hello, world!"
System.out.println(myString.length()); // prints 13
}
}
In this example, we create a new String
object called myString
and set its value to "Hello, world!". We then print the string using System.out.println()
and get its length using the length()
method.
I hope this helps! Let me know if you have any questions or need further clarification.