Java面试宝典——Java基础知识总结

    public class Student {
    private String name;
    private int age;
    private String address;
    private double score;
    
    public void study() {
        System.out.println("正在学习...");
    }
    
    // Getter and Setter methods for the member variables
    }
    
    
      
      
      
      
      
      
      
      
      
      
      
      
    
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    // Creating an object of type Student
    Student student = new Student();
    
    // Setting the values of the properties of the object
    student.setName("John");
    student.setAge(18);
    student.setAddress("New York");
    student.setScore(90.0);
    
    // Calling a method on the object to perform some action
    student.study();
    
    
      
      
      
      
      
      
      
      
      
      
      
    
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    // Assigning one object reference to another variable
    Person person1 = new Person();
    Person person2 = person1;
    
    System.out.println("person1: " + person1);   // Output: person1: com.example.Person@4e4d2b8c
    System.out.println("person2: " + person2);   // Output: person2: com.example.Person@4e4d2b8c
    
    // Modifying the properties of one object affects both references
    person1.name = "Alice";
    
    System.out.println("person1: " + person1.getName());    // Output: Alice
    System.out.println("person2: " + person2.getName());    // Output: Alice
    
    
      
      
      
      
      
      
      
      
      
      
      
      
    
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    // Package declaration statement
    package com.example.package_name;
    
    
      
      
    
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    // Example usages of modifiers in classes, interfaces, methods, fields
    
    // Access modifiers
    public class MyClass {}
    protected class AnotherClass extends MyClass {}
    class YetAnotherClass implements MyInterface {}
    private void myMethod() {}
    public static final long serialVersionUID = 1L;
    
    // Inheritance modifiers
    class ChildClass extends ParentClass {}
    interface MyInterface extends OtherInterface {}
    abstract class AbstractClass {}
    abstract interface AbstractInterface {}
    final class FinalClass {}
    static class StaticClass {}
    synchronized class SynchronizedClass {}
    volatile class VolatileClass {}
    transient volatile float price;
    
    // Variable modifiers
    int x = 10;      // Not modifiable by subclasses
    final double y = Math.PI;     // Value cannot be changed after initialization
    static String message = "Hello World!";       // Same value accessible from any instance
    ThreadLocal<String> threadName = ThreadLocal.withInitial(() -> getNameOfCurrentThread()); 
                                                // Value is unique per thread
    
    
    
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
    
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    // An example implementation of abstract class Shape using Rectangle as subclass
    abstract class Shape {
    protected Point center;
    
    public abstract double area();
    
    public void translate(double dx, double dy) {
        this.center.translate(dx, dy);
    }
    
    // Constructor
    public Shape(Point center) {
        this.center = center;
    }
    }
    
    class Circle extends Shape {
    private double radius;
    
    @Override
    public double area() {
        return Math.PI * Math.pow(radius, 2);
    }
    
    // Constructor
    public Circle(Point center, double radius) {
        super(center);
        this.radius = radius;
    }
    }
    
    class Rectangle extends Shape {
    private double width;
    private double height;
    
    @Override
    public double area() {
        return width * height;
    }
    
    // Constructor
    public Rectangle(Point center, double width, double height) {
        super(center);
        this.width = width;
        this.height = height;
    }
    }
    
    // An example implementation of interface Animal with two implementations Cat and Dog
    interface Animal {
    void move();
    }
    
    class Cat implements Animal {
    @Override
    public void move() {
        System.out.println("Meow!");
    }
    }
    
    class Dog implements Animal {
    @Override
    public void move() {
        System.out.println("Woof!");
    }
    }
    
    
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
    
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