public class ObjectStu {
	/*Object類:java里所有類的父類,頂層的類
 *equals:判斷兩個(gè)對(duì)象是否"相等";
 *hashcode:返回一個(gè)對(duì)象的哈希碼值,是一個(gè)整數(shù)
 *因?yàn)橹蟮娜萜?例如hashset和hashMap會(huì)對(duì)元素進(jìn)行去重的處理;所以equals和hashcode需要同時(shí)重寫;
 *重寫之后需要滿足的標(biāo)準(zhǔn):
 *當(dāng)equals的結(jié)果為true的時(shí)候,要求兩個(gè)對(duì)象的hashcode值相等;
 *當(dāng)equals的結(jié)果為false的時(shí)候,要求兩個(gè)對(duì)象的hashcode值不等;(hashcode可以相等,但是如果不等可以提升效率)
 *toString:返回對(duì)象的字符串表示
 *作用:方便程序內(nèi)查看對(duì)象屬性,方便調(diào)試代碼
 *debug學(xué)習(xí):
 *1.在可能出現(xiàn)bug的地方設(shè)置斷點(diǎn)
 *2.run as debug
 *3.f6,執(zhí)行當(dāng)前代碼;f5,進(jìn)入當(dāng)前本句代碼的方法內(nèi)部;f8,快速跳到下一個(gè)斷點(diǎn),如果沒(méi)有下一個(gè)斷點(diǎn),運(yùn)行余下所有代碼
 *equals:
 *1.一致性:使用對(duì)象A調(diào)用equals和對(duì)象b進(jìn)行比較,每一次的結(jié)果都應(yīng)該一樣
 *2.自反性:對(duì)象A調(diào)用equals比較對(duì)象b和對(duì)象b調(diào)用equals比較對(duì)象a的結(jié)果應(yīng)該一樣
 */
	public static void main(String[] args)
	 {
		Person per = new Person("小王",10,150);
		Person per1 = new Person("小王",20,140);
		Person per2 = per;
		System.out.println(per==per1);
		System.out.println(per.equals(per1));
		String str = "123";
		str.equals("123");
		str.hashCode();
		System.out.println(per.hashCode());
		System.out.println(per1.hashCode());
		System.out.println(per2.hashCode());
		System.out.println(per);
		System.out.println(per1);
	}
}
class Person {
	String name;
	int age;
	int height;
	public Person(String name, int age,int height)
	 {
		super();
		this.height = height;
		this.name = name;
		this.age = age;
	}
	/*@Override
 public boolean equals(Object obj)
 {
 if(this==obj){
  return true;
 }
 if(obj instanceof Person){
  Person per = (Person)obj;
  if(this.name.equals(per.name)&&this.age==per.age){
  return true;
  }
 }
 return false;
 }*/
	//重寫hashcode
	/*@Override
 public int hashCode(){
 return name.hashCode()+age*31+height*31;
 }*/
	@Override
	 public int hashCode()
	 {
		final int prime = 31;
		int result = 1;
		result = prime * result + age;
		result = prime * result + height;
		result = prime * result + ((name == null) ? 0 : name.hashCode());
		return result;
	}
	@Override
	 public Boolean equals(Object obj)
	 {
		if (this == obj)
		  return true;
		if (obj == null)
		  return false;
		if (getClass() != obj.getClass())
		  return false;
		Person other = (Person) obj;
		if (age != other.age)
		  return false;
		if (height != other.height)
		  return false;
		if (name == null)
		 {
			if (other.name != null)
			  return false;
		} else if (!name.equals(other.name))
		  return false;
		return true;
	}
	@Override
	 public String toString()
	 {
		return "Person[name="+name+",age="+age+"]";
	}
}