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School.java
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141 lines (124 loc) · 4.39 KB
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package students;
import java.util.ArrayList;
import java.util.List;
interface StudentCriterion {
boolean test(Student s);
}
interface Silly {
boolean daft(Student s);
}
//class SmartnessCriterion implements StudentCriterion {
// @Override
// public boolean test(Student s) {
// return s.getGpa() > 3.0F;
// }
//}
//
//class EnthusiasmCriterion implements StudentCriterion {
// @Override
// public boolean test(Student s) {
// return s.getCourses().size() > 3;
// }
//}
//
public final class School {
public static StudentCriterion inverse(StudentCriterion crit) {
return s -> !crit.test(s);
}
public static StudentCriterion and(StudentCriterion c1, StudentCriterion c2) {
return s -> c1.test(s) && c2.test(s);
}
public static StudentCriterion or(StudentCriterion c1, StudentCriterion c2) {
return s -> c1.test(s) || c2.test(s);
}
public static void showAll(List<Student> ls) {
for (Student s : ls) {
System.out.println("> " + s);
}
System.out.println("========================================");
}
// BAD!!! Mixes selection of smart students with what to do with them!
// public static void showAllSmart(List<Student> ls) {
// for (Student s : ls) {
// if (s.getGpa() > 3) {
// System.out.println("> " + s);
// }
// }
// System.out.println("========================================");
// }
public static List<Student> getByCriterion(Iterable<Student> ls, StudentCriterion criterion) {
List<Student> result = new ArrayList<>();
for (Student s : ls) {
if (criterion.test(s)) {
result.add(s);
}
}
return result;
}
public static List<Student> getSmart(Iterable<Student> ls, float threshold) {
List<Student> result = new ArrayList<>();
for (Student s : ls) {
if (s.getGpa() > threshold) {
result.add(s);
}
}
return result;
}
public static List<Student> getEnthusiastic(Iterable<Student> ls, int threshold) {
List<Student> result = new ArrayList<>();
for (Student s : ls) {
if (s.getCourses().size() > threshold) {
result.add(s);
}
}
return result;
}
// public static List<Student> getFairlySmart(Iterable<Student> ls) {
// List<Student> result = new ArrayList<>();
// for (Student s : ls) {
// if (s.getGpa() > 2.6) {
// result.add(s);
// }
// }
// return result;
// }
//
public static void main(String[] args) {
List<Student> school = List.of(
Student.ofNameGpaCourses("Fred", 2.2F, "Math", "Physics", "Politics", "History of Art"),
Student.ofNameGpaCourses("Jim", 2.7F, "Math"),
Student.ofNameGpaCourses("Tony", 2.3F, "Math", "Art", "Engineering"),
Student.ofNameGpaCourses("Alice", 3.5F, "Math"),
Student.ofNameGpaCourses("Sarah", 3.7F, "Math", "Philosophy", "German Literature"),
Student.ofNameGpaCourses("Sheila", 3.8F, "Math", "Physics", "Astrophysics", "Quantum Mechanics")
);
showAll(school);
showAll(getSmart(school, 3.0F));
// showAll(getFairlySmart(school));
showAll(getSmart(school, 2.6F));
showAll(getEnthusiastic(school, 1));
System.out.println("Using behavior parameter");
showAll(getByCriterion(school, Student.getSmartnessCriterion(2.6F)));
showAll(getByCriterion(school, Student.getEnthusiasmCriterion()));
showAll(getByCriterion(school, s -> s.getCourses().size() > 3));
StudentCriterion x = s -> s.getCourses().size() > 3;
// ((Silly)(s -> s.getCourses().size() > 3)).test(school.get(0)) ;
// ((StudentCriterion)(s -> s.getCourses().size() > 3)).test(school.get(0)) ;
System.out.println("--------------------------------");
StudentCriterion smart = Student.getSmartnessCriterion(3F);
System.out.println("Smart: ");
showAll(getByCriterion(school, smart));
StudentCriterion notSmart = inverse(smart);
System.out.println("Not Smart: ");
showAll(getByCriterion(school, notSmart));
System.out.println("--------------------------------");
StudentCriterion enthusiastic = Student.getEnthusiasmCriterion();
System.out.println("Enthusiastic: ");
showAll(getByCriterion(school, enthusiastic));
StudentCriterion notEnthusiastic = inverse(enthusiastic);
System.out.println("Not Enthusiastic: ");
showAll(getByCriterion(school, notEnthusiastic));
System.out.println("Enthusiastic and not smart");
showAll(getByCriterion(school, and(enthusiastic, notSmart)));
}
}