Java覆寫equeal和hashCode方法

使用Apache commons提供的commons-lang-xxx.jar包

    下載地址：http://commons.apache.org/lang/


    覆寫equals使用：org.apache.commons.lang.builder.EqualsBuilder


    覆寫hashCode使用：org.apache.commons.lang.builder.HashCodeBuilder



來自apache官方的實例

public class Person {

   String name;

   int age;

   boolean smoker;

   ...


  // overwrite "equals"

  public boolean equals(Object obj) {

   if (obj == null) { return false; }

   if (obj == this) { return true; }

   if (obj.getClass() != getClass()) {

     return false;

   }

   Person rhs = (Person) obj;

   return new EqualsBuilder()

                 .appendSuper(super.equals(obj))

                 .append(field1, rhs.field1)

                 .append(field2, rhs.field2)

                 .append(field3, rhs.field3)

                 .isEquals();

  }


    // overwrite "hashCode"

   public int hashCode() {

     // you pick a hard-coded, randomly chosen, non-zero, odd number

     // ideally different for each class

     return new HashCodeBuilder(17, 37).

       append(name).

       append(age).

       append(smoker).

       toHashCode();

   }


 }