Re: how to search an array of objects?
- From: John Ersatznom <j.ersatz@xxxxxxxxxxxxxxx>
- Date: Mon, 08 Jan 2007 05:19:27 -0500
Lew wrote:
public class Student
{
private String name;
public String getName() { return name; }
public void setName( String name ) { this.name = name; }
private int module;
public int getModule() { return module; }
public void setModule( int module ) { this.name = module; }
private float mark;
public float getMark() { return mark; }
public void setMark( float mark ) { this.name = mark; }
}
Ewww. Student is a value object with no behavior and no likely implementation changes save to add or remove fields, so it should really just be
public class Student {
public final String name;
public int module; // Consider making this an object too
public float mark; // Consider making this an int, 1-100,
// or even an enum with A, B, C, D, F
public Student (String name, int module, float mark) {
this.name = name;
this.module = module;
this.mark = mark;
}
}
Name made final since it's used as a map key.
Of course, a student is actually likely to have marks in many classes, which suggests
public class Student {
public final String name;
// And address, and GPA, and other stuff
// equals() and hashCode() methods
}
public class Course { whatever } // or Module or whatever
public class SchoolInfo {
private Map<String, Student> students;
private Map<Student, List<Course>> whosTakingWhat;
private Map<Course, List<Student>> whosInWhat;
private static class StudentInCourse {
public final Student student;
public final Course course;
public StudentInCourse (Student student,Course course) {
this.student = student;
this.course = course;
}
// obvious equals() and hashCode() go here
}
private Map<StudentInCourse, Integer> marks;
// whatever
}
Or perhaps even:
public class Course {
private Map<Student, Integer> marks;
public Set<Student> getTakers () { return marks.keySet(); }
public boolean contains (Student student) {
return marks.containsKey(student);
}
/**
* @throws NPE if student isn't taking this course
*/
public int getMark (Student student) {
return marks.get(student).intValue();
}
public int setMark ...
}
and SchoolInfo just has Map<String, Student> students and Map<String, Course> courses, with Course responsible for listings its students and SchoolInfo able to supply an inner class instance giving a Set view of the courses a given student is taking by using the objects in "courses" and their knowledge of their students (via "contains")...
.
- References:
- how to search an array of objects?
- From: Digging4fire
- Re: how to search an array of objects?
- From: Brandon McCombs
- Re: how to search an array of objects?
- From: Lew
- how to search an array of objects?
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