学步园

当使用一个类作为hashMap的key时，需要重写该类的equals()和hashCod()的方法

类的定义代码：

public class Object1{

   private Long id;

   private String code;

   private String name;

   private Integer type;

   public Node(){

   }

       

   public Node(String code,String type){

       this.setCode(code);

       this.setType(type);

   }

   

    public Long getId() {
return id;
}

public void setId(Long id) {
this.id = id;
}

       public Integer getType() {
return type;
}

public void setType(Integer type) {
this.type =type;
}

              

       public Integer getCode() {
return code;
}

public void setCode(String code) {
this.code =code;
} 

      

        public Integer getName() {
return name;
}

public void setName(String name) {
this.name =name;
} 

@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof Object1))
return false;

Node other = (Object1) obj;

if (other.getId() != null && this.getId() != null && other.getId().longValue() == this.getId().longValue()) {
return true;
}

if (other.getType() != null && this.getType() != null && other.getType() != null
&& this.geType() != null
&& other.getCode() == this.getCode()
&& other.getCode() == this.getCode()) {
return true;
}
return false;
}

        @Override
public int hashCode()  {

if(this.getCode() != null && this.getType() != null){
String hashCode = String.valueOf(getType()) + "_" + String.valueOf(getCode());
return hashCode.hashCode();
}

if(id != null){
return id.intValue();
}

return 0;
}

}

小插曲：

question：Using an object as key for a hashmap in Java

google answer：