hashCode和equals重写

public class Student {
private String id;
private String name;

public Student(String id, String name) {
this.id = id;
this.name = name;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}

public class EqualTest {

/**set集合存放无序，不重复的元素
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Student student1=new Student("1", "Tom");
Student student2=new Student("1", "Tom");
System.out.println("内容相同的两个Student对象是否相同："+student1.equals(student2));
Set<Student> set=new HashSet<Student>();
set.add(student1);
set.add(student2);
System.out.println(set);
}
}

内容相同的两个Student对象是否相同：false
[com.jxufe.equal.Student@64c3c749, com.jxufe.equal.Student@7150bd4d]

public class Student {
private String id;
private String name;

public Student(String id, String name) {
this.id = id;
this.name = name;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
//hashCode()和equals()同时重写
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.hashCode());
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 (!(obj instanceof Student))
return false;
Student other = (Student) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}

}

内容相同的两个Student对象是否相同：true
[com.jxufe.equal.Student@152e2]