package devmanuals.com;

import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.Set;

class CMReplace1 implements Runnable {
	ConcurrentMap<Integer, String> cmp;
	String name;

	public CMReplace1(String name, ConcurrentMap<Integer, String> cmp) {
		this.cmp = cmp;
		this.name = name;
	}

	public void run() {

		System.out.println(name + " maps the element ");
		cmp.put(1, "A");
		cmp.put(3, "C");
		cmp.put(4, "D");
		System.out.println(cmp);
		System.out.println("Size of Map = " + cmp.size());
		Set<Integer> s = cmp.keySet();
		System.out.println("Key set of map = " + s);
		// here implementation of this method will show the previously
		// associated value with specified key.
		String s2 = cmp.replace(2, "E");
		System.out.println("Previously associated value of '2' was : " + "'"
				+ s2 + "'");
		try {
			Thread.sleep(400);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}
}

class CMReplace2 implements Runnable {
	String name;
	ConcurrentMap<Integer, String> cmp;

	public CMReplace2(String name, ConcurrentMap<Integer, String> cmp) {
		this.cmp = cmp;
		this.name = name;
	}

	public void run() {
		try {
			// here implementation of method will return the previously
			// associated value.
			cmp.put(2,"E");
			String s = cmp.replace(2, "D");
			System.out.println("Previously associated value of '2' was : "
					+ "'" + s + "'");
			// here implementation of method will return null it shows 
			//there is no mapping exist into the map.
			String s1 = cmp.replace(2, "B");
			System.out.println("Previously associated value of '2' was : "
					+ "'" + s1 + "'");
			Thread.sleep(1500);
			System.out.println("Set of key = " + cmp.keySet());
			System.out.println("Size of Map = " + cmp.size());
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}
}

public class CMReplace {
	public static void main(String args[]) {
		ConcurrentMap<Integer, String> cmp = new ConcurrentHashMap<Integer, String>();
		Runnable a = new CMReplace1("A", cmp);
		new Thread(a).start();
		try {
			Thread.sleep(400);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		Runnable b = new CMReplace2("B", cmp);
		new Thread(b).start();
	}
}