Effective-Java：Effective Java的所有练习程序

public class Student { String name; String major; int age; int yearOfGraduation; double GPA; int currentSemeseter; // Builder Pattern public static class Builder { // Required Parameters String name; String major; // Optional Parameters -- Initialized with zero int age = 0; int yearOfGraduation = 0; double GPA = 0; int currentSemeseter = 0; public Builder(String name, String major) { this.name = name; this.major = major; } public Builder age(int val) { this.age = val; return this; } public Builder yearOfGraduation(int val) { this.yearOfGraduation = val; return this; } public Builder GPA(double val) { this.GPA = val; return this; } public Builder currentSemester(int val) { this.currentSemeseter = val; return this; } public Student build() { return (new Student(this)); } } private Student(Builder builder) { this.name = builder.name; this.major = builder.major; this.age = builder.age; this.yearOfGraduation = builder.yearOfGraduation; this.GPA = builder.GPA; this.currentSemeseter = builder.currentSemeseter; } public int semesterIncrement() { return this.currentSemeseter++; } public void displayStudentInfo() { System.out.printf(" Name: %s\n Major: %s\n Age: %d\n Year Of Graduation: %d\n GPA: %f\n Current Semester: %d\n", this.name, this.major, this.age, this.yearOfGraduation, this.GPA, this.currentSemeseter); } }