How to limit the number of entries in a Java hash table?

Is there a technique so that I can specify a number n so that when inserting the (N1) th entry, the oldest entry is deleted first to ensure that the size of the hash table is always limited to n?

Solution

LinkedHashMap does. Please refer to the Javadoc for removeeldestentry method

Such things should be done by trick, which will delete the oldest insert entry:

Map map = new LinkedHashMap() {
    @Override
    protected boolean removeEldestEntry(Entry eldest) {
        return size() > N;
    }
};

You can also delete the oldest access entry by specifying it in the constructor:

Map map = new LinkedHashMap(16,0.75f,true) {
        @Override
        protected boolean removeEldestEntry(Entry eldest) {
            return size() > N;
        }
    };