选项 1.使用比较器
public class Cmp<K extends Comparable<K>, V> implements Comparator<Pair<K, V>> {
@Override
public int compare(Pair<K, V> o1, Pair<K, V> o2) {
return o1.k.compareTo(o2.k);
}
}
public class Utils {
public static <K extends Comparable<K>, V> Collection<Pair<K, V>> sortPairCollection(
Collection<Pair<K, V>> col) {
ArrayList<Pair<K, V>> list = new ArrayList<>();
Collections.sort(list, new Cmp<>());
return list;
}
}
选项 2。
实现可比性
public class Pair<K extends Comparable<K>, V> implements Comparable<Pair<K, V>> {
private K k;
private V v;
@Override
public int compareTo(Pair<K, V> o) {
return k.compareTo(o.k);
}
}
public class Utils {
public static <K extends Comparable<K>, V> Collection<Pair<K, V>> sortPairCollection(Collection<Pair<K, V>> col) {
ArrayList<Pair<K, V>> list = new ArrayList<>();
Collections.sort(list);
return list;
}
}
Or just
public class Utils {
public static <K extends Comparable<K>, V> Collection<Pair<K, V>> sortPairCollection(Collection<Pair<K, V>> col) {
ArrayList<Pair<K, V>> list = new ArrayList<>();
Collections.sort(list, (p, o) -> p.k.compareTo(o.k));
return list;
}
}
顺便说一句,您不必为静态方法创建实例。只需调用
Utils.sortPairCollection(list);