浅析Java中如何优雅地处理null值

public class Student {
    private String name;
    private Integer age;

    // 全参构造函数
    public Student(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public Integer getAge() {
        return age;
    }
    // toString 方法
    @Override
    public String toString() {
        return"Student{" + "name='" + name + '\'' + ", age=" + age + '}';
    }
}

public class OptionalTest {
    public static void main(String[] args) {
        Student student = new Student("Bob", 18);
        Optional<Student> studentOpt = Optional.ofNullable(student);
    }
}

// 编写方法 1
if (student == null) {
    return UNKNOWN_STUDENT;
} else {
    return student;
}
// 编写方法 2
if (!studentOpt.isPresent()) {
    return UNKNOWN_STUDENT;
} else {
    return studentOpt.get();
}

// if 语句
if (student!= null) {
    System.out.println(student);
}
// Optional
studentOpt.ifPresent(System.out::println);

// if 语句
if (student == null) {
    return UNKNOWN_STUDENT; // 或抛出异常
} else {
    return student;
}
// Optional
return studentOpt.orElse(UNKNOWN_STUDENT);
return studentOpt.orElseThrow(RuntimeException::new);

// if 语句
if (student == null) {
    return UNKNOWN_STUDENT;
} else {
    return generateWithFunction();
}
// Optional
return studentOpt.orElseGet(() -> generateWithFunction());

// Java 7
if (student!= null) {
    String name = student.getName();
    if (name!= null) {
        return name;
    } else {
        return null;
    }
} else {
    return null;
}
// Java 8
return studentOpt.map(Student::getName).orElse(null);