package com.semanticsquare.generics;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

public class GenericsDemo{
	
	public static void main(String[] args) {
		Container<String> stringStore = new Store<>();
		stringStore.set("java");
		//stringStore.set(1);
		System.out.println(stringStore.get());
		
		Container<Integer> integerStore = new Store<>();
		integerStore.set(1);
		System.out.println(integerStore.get());
		
		Container<List<Integer>> listStore = new Store<>();
		listStore.set(Arrays.asList(1, 2, 3));
		System.out.println(listStore.get());
		
		//Container<int> intStore = new Store<>();
		List<Number> list = new ArrayList<>();
		list.add(new Integer(1));
		list.add(new Double(22.0));
		//list.add(new String("22.0"));
		
		List[] array = new List[2];
		array[0] = new ArrayList();
		array[1] = new LinkedList();
		
		// Raw type demo:		
		// rawTypeTest();		
		
		List<String> strList1 = Arrays.asList("a", "b", "c");
		List<String> strList2 = Arrays.asList("b", "c", "d");
		//getCommonElementsCount(strList1, strList2);
		
		// Wildcard
		getCommonElementsCountWithWildcard(strList1, strList2);
		
		Container<?> someStore = stringStore;
		Object object = someStore.get();
		System.out.println("Stored element: " + object);	
		
		List<Integer> intList1 = Arrays.asList(1, 2);
		List<Integer> intList2 = Arrays.asList(3, 4);
		invalidAggregate(intList1, intList2, new ArrayList());
		
		//go(new ArrayList<Integer>());
		//go(new Integer[1]);
	}
	
	// Invariance
	static void go(List<Number> list) {}
	
	// Covariance
	static void go(Number[] list) {
		list[0] = 24.4;
	}	
	
	public static void invalidAggregate(List<?> l1, List<?> l2, List<?> l3) {
		//l3.addAll(null); // null ok
		//l3.addAll(l2);
	}
	
	public static int getCommonElementsCountWithWildcard(List<?> list1, List<?> list2) {
		int count = 0;
		for (Object element : list1) {
			if (list2.contains(element)) {
				count++;
			}
		}
		System.out.println("Common elements count: " + count);
		return count;
	}
	
	public static int getCommonElementsCount(List list1, List list2) {
		int count = 0;
		for (Object element : list1) {
			if (list2.contains(element)) {
				count++;
			}
		}
		System.out.println("Common elements count: " + count);
		return count;
	}
	
	public static void rawTypeTest() {
		System.out.println("\n\nInside rawTypeTest ...");
		int ISBN = 1505297729;
	    List<Double> prices = new ArrayList<>();
	    
	    HalfIntegrator.getPrice(ISBN, prices);
	    Double price = prices.get(0);	    
	}
}

class HalfIntegrator {
	
	public static void getPrice(int ISBN, List prices) {
		prices.add(45);
	}
	
}

interface Container<T> {
	void set(T a);
	T get();
}

class Store<T> implements Container<T> {
	private T a;
	
	public void set(T a) {
		this.a = a;
	}
	
	public T get() {
		return a;
	}
}