這樣吧,這次先上程式碼,再敘述

public class Student {
  private String name;
  private int age;
  private Student(Builder builder){
    this.name=builder.name;
    this.age=builder.age;
  }  
    public String getName(){
        return name;
      }  
    public void setName(String name){
        this.name = name;  
    }  
    public
 
 int getAge(){
        return age;
      }  
    public void setAge(int age){
        this.age = age;
      } 

    static class Builder{
        private String name;
        private int age;
        public Builder name(String name){
          this.name=name;
          return this;
        }
        public
 
 Builder age(int age){
          this.age=age;
          return this;
        }
        public Student build(){
          return new Student(this);
        }
      }
}

其實大體是這樣設計得

• 在實體類中有一些屬性,然後在其內部靜態類Builder中也有一樣的屬性
• 將實體類中的構造方法私有化
• 實體類由Builder構建出來,實體類中的屬性值由構造時傳入的Builder物件為其賦值
• Builder的每個方法都是給自己的屬性賦值,並返回自己Builder的引用

達到上面4點,則在構建時就可以這樣寫

Student.Builder builder=new Student.Builder();
Student student=builder
  .name("小明")
  .age(10)
  .build();

很爽吧…nice