Java中的Object类的常用方法和代码示例

Java中的Object类是所有类的父类，提供了一些常用的方法，下面是常用的方法和代码示例：

1. equals(Object obj)方法：判断当前对象是否和另一个对象相等，即比较两个对象的内容是否相同。

public class Person {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null || getClass() != obj.getClass()) return false;
        Person person = (Person) obj;
        return age == person.age && Objects.equals(name, person.name);
    }
}

// 测试代码
Person p1 = new Person("Tom", 18);
Person p2 = new Person("Tom", 18);
System.out.println(p1.equals(p2)); // true

2. hashCode()方法：返回当前对象的哈希码，一般用于哈希表等数据结构中。

public class Person {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public int hashCode() {
        return Objects.hash(name, age);
    }
}

// 测试代码
Person p1 = new Person("Tom", 18);
System.out.println(p1.hashCode()); // 2316056

3. toString()方法：返回当前对象的字符串表示。

public class Person {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

// 测试代码
Person p1 = new Person("Tom", 18);
System.out.println(p1.toString()); // Person{name='Tom', age=18}

4. getClass()方法：返回当前对象的类类型。

public class Person {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
}

// 测试代码
Person p1 = new Person("Tom", 18);
System.out.println(p1.getClass()); // class Person

5. clone()方法：复制当前对象，返回一个新的对象。

public class Person implements Cloneable {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

// 测试代码
Person p1 = new Person("Tom", 18);
Person p2 = (Person) p1.clone();
System.out.println(p1 == p2); // false