builder模式

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package study;     import lombok.Data;   @Data public class Student  {     Integer age;     String name;     String address ;     public Student() {     }       public Student(Builder builder){         this.name = builder.name;     }       public static  Builder builder() {         return new Builder();     }     public static final class Builder{         String name;         Integer age;           public Builder age (Integer age){             this.age  = age;             return this;         }         public Builder name (String name){             if (name ==null){                 return this;             }             this.name  = name;             return this;         }           public Student build(){               return new Student(this);         }     }       @Override     public String toString() {         return "Student{" +                 "name='" + name + '\'' +                 '}';     } }

　　

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package patterns.builder;   import study.Student;   public class Test {     public static void main(String[] args) {         Student empty = new Student(); //student1         Student student =  Student.builder()                 .name(empty.getAddress())                 .age(18)                 .build();         System.out.println("student = " + student);       } }