. 使用HashSet和TreeSet存储多个商品信息，遍历并输出；其中商品属性：编号，名称，单价，出版社；要求向其中添加多个相同的商品，验证集合中元素的唯一性。
提示：向HashSet中添加自定义类的对象信息，需要重写hashCode和equals( )
向TreeSet中添加自定义类的对象信息，需要实现Comparable接口，指定比较规则
TreeSet
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.TreeSet;
public class Goodss implements Comparable<Goodss>{
int bh;
String name;
double much;
String work;
public Goodss(int bh, String name, double much, String work) {
this.bh = bh;
this.name = name;
this.much = much;
this.work = work;
}
public static void main(String[] args) {
Goodss a = new Goodss(1, "钢铁是怎样练成的", 12.5, "小日本出版社");
Goodss a1 = new Goodss(2, "坏蛋是怎样练成的", 15.0, "小*出版社");
Goodss a2 = new Goodss(3, "天才是怎样练成的", 20.5, "小美国出版社");
Goodss a3 = new Goodss(3, "天才是怎样练成的", 20.5, "小美国出版社");
TreeSet<Goodss> ttw = new TreeSet<Goodss>();
ttw.add(a);
ttw.add(a1);
ttw.add(a2);
ttw.add(a3);
for(Goodss r:ttw){
System.out.println(r.name+"\t"+r.work+"\t"+r.bh+"\t"+r.much);
}
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + bh;
long temp;
temp = Double.doubleToLongBits(much);
result = prime * result + (int) (temp ^ (temp >>> 32));
result = prime * result + ((name == null) ? 0 : name.hashCode());
result = prime * result + ((work == null) ? 0 : work.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;
Goodss other = (Goodss) obj;
if (bh != other.bh)
return false;
if (Double.doubleToLongBits(much) != Double
.doubleToLongBits(other.much))
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
if (work == null) {
if (other.work != null)
return false;
} else if (!work.equals(other.work))
return false;
return true;
}
@Override
public int compareTo(Goodss o) {
if(this.bh>o.bh){
return 1;
}if(this.bh<o.bh){
return -1;
}
return 0;
}
}