implement interface

import java.util.Arrays;


interface TrivialSet<Character> {
	 boolean isEmpty();
	 boolean isMember(Character x);
	 void add(Character x);
	 void remove(Character x);
 }


class CharSet implements TrivialSet<Character> {

	   private boolean[] elements;
	   private int count;
	   public CharSet() {
		   elements = new boolean[Character.MAX_CODE_POINT];
		   Arrays.fill(elements,false);
		   count = 0;
	   }

	   public boolean isMember(Character x) {
		  return elements[(char) x];
	   }

	   public boolean isEmpty() {
		  return count == 0;
	   }

	   public void add(Character x) {
		  if (!elements[(char) x]) {
				count++;
				elements[(char) x] = true;
		 }
	  }

	   public void remove(Character x) {
		  if (elements[(char) x]) {
			   count--;
			   elements[(char) x] = false;
		 }
	  }
 }

The program implement interfaces but how program control the index of array by use (char x) any one can explain program how its works.

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