Generic Cooldown Java Library, currently using in my plugins.

Cooldown.java

import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.TimeUnit;

public class Cooldown<T> {

    private Map<T, Long> map;

    public Cooldown() {
        this.map = new WeakHashMap<>();
    }

    public boolean isOnCooldown(T key) {
        return this.map.containsKey(key) && this.map.get(key) >= System.currentTimeMillis();
    }

    public boolean putOnCooldown(T key, int time, TimeUnit unit) {
        if (isOnCooldown(key)) {
            return true;
        } else {
            this.map.remove(key);
            this.map.put(key, unit.toMillis(time) + System.currentTimeMillis());
            return false;
        }
    }

    public long getRemainingTime(T key) {
        return this.map.getOrDefault(key, System.currentTimeMillis()) - System.currentTimeMillis();
    }
}