Java.util.HashSet
lastmod 2020-09-09created 2020-09-091 edits
Notes on HashSet, a Set (unordered, no duplicate insertion) with an added hash (Hash) function.
Simple usage
Simple usage is as follows.
HashSet<String> hs = new HashSet<>();
hs.add("주원?병준");
hs.add("몽골용단");
hs.add("안피곤인애");
hs.add("안피곤인애");
System.out.println(hs);
HashSet<Student> hs2 = new HashSet<>();
hs2.add(new Student("주원병준", 174, 95));
hs2.add(new Student("몽골용단", 174, 99));
hs2.add(new Student("멋쟁이완샘", 184, 1000));
hs2.add(new Student("멋쟁이완샘", 184, 1000));
System.out.println(hs2);
Custom HashSet
To customize a HashSet, you must override the hashCode() and equals() methods.
@Override
public int hashCode() {
return name.hashCode();
}
@Override
public boolean equals(Object obj) {
if(!(obj instanceof Student)) {
return false;
}
Student s = (Student)obj;
return name.equals(s.name);
}