JAVA中Object的常用方法

boolean equals(Object obj)
          指示其他某个对象是否与此对象“相等”。
protected  void finalize()
          当垃圾回收器确定不存在对该对象的更多引用时，由对象的垃圾回收器调用此方法。
 int hashCode()
          返回该对象的哈希码值,哈希map中用到，具体可以查看数据结构。
 String toString()
          返回该对象的字符串表示。

//测试Object用法
public class TestObject {
    public static void main(String[] args) {
       //创建对象测试
       Person p = new Person("熊大",20,10,"森林");
       System.out.println(p);//要是不重写toString()就是使用的Object提供的默认方式只能打印对象在内存的地址
       System.out.println(p);//由于重写了toString()所以打印的是属性的值
    }
}
//定义类，提供属性
class  Person{
    //构造：source-generate constrctor using fileds
    public Person() {}
    public Person(String name, int age, double salary, String addr) {
       this.name = name;
       this.age = age;
       this.salary = salary;
       this.addr = addr;
    }
    //属性
    private String name;
    private int age;
    private double salary;
    private String addr;
    //set() get()
    public String getName() {
       return name;
    }
    public void setName(String name) {
       this.name = name;
    }
    public int getAge() {
       return age;
    }
    public void setAge(int age) {
       this.age = age;
    }
    public double getSalary() {
       return salary;
    }
    public void setSalary(double salary) {
       this.salary = salary;
    }
    public String getAddr() {
       return addr;
    }
    public void setAddr(String addr) {
       this.addr = addr;
    }
    //toString()：source - generate toString()-ok
    @Override//重写的是Object提供的toString()是为了查看属性值
    public String toString() {
       return "Person [name=" + name + ", age=" + age + ", salary=" + salary + ", addr=" + addr + "]";
    }
}

public class TestArea {
    public static void main(String[] args) {
       //基础类型是按值比较
       int i1 = 10;
       int i2 = 10;
       int i3 = 12;
       System.out.println(i1==i2);//true
       System.out.println(i1==i3); //false
       //对象为引用类型，引用类型按内存地址比较
       //如果不想比较地址，可以重写equals方法
       Tiger t1 = new Tiger();
       Tiger t2 = new Tiger();
       Tiger t3 = t1;
       System.out.println(t1);
       System.out.println(t2);
       System.out.println(t3);
       System.out.println(t1.equals(t2));//false
       System.out.println(t1 == t2);//false
       System.out.println(t1.equals(t3));//true
       System.out.println(t1 == t3);//true
    }
}

//测试equals()  ==
public class TestObject {
   public static void main(String[] args) {
       //1，==比较八大基本类型时：判断的是值
       int a = 1;
       int b = 1;
       System.out.println(a==b);//true
       //2，==比较对象时，比较的是对象的地址值
       Integer x = 5;
       Integer y = 10;
       Integer z = x;//把x的地址赋值给了z
       System.out.println(x==y);//false
       System.out.println(x==z);//true      
       //3，equals()用来比较对象存着的值
       System.out.println(x.equals(z));//true
       //4，测试hashCode()哈希值
       System.out.println(x.hashCode());//5
       System.out.println(y.hashCode());//10
       System.out.println(z.hashCode());//5
   }
}
//测试equals()  ==
public class TestObject {
   public static void main(String[] args) {
       //1，==比较八大基本类型时：判断的是值
       int a = 1;
       int b = 1;
       System.out.println(a==b);//true
       //2，==比较对象时，比较的是对象的地址值
       Integer x = 5;
       Integer y = 10;
       Integer z = x;//把x的地址赋值给了z
       System.out.println(x==y);//false
       System.out.println(x==z);//true      
       //3，equals()用来比较对象存着的值
       System.out.println(x.equals(z));//true
       //4，测试hashCode()哈希值
       System.out.println(x.hashCode());//5
       System.out.println(y.hashCode());//10
       System.out.println(z.hashCode());//5
   }
}