Thread sync example and concurrent modification exception added

src/ThreadTest/ThreadCreator.java

@@ -0,0 +1,25 @@
+package ThreadTest;
+
+public class ThreadCreator extends Thread
+{
+	syncobj a;
+	int ThrdCnt=0;
+	public ThreadCreator(syncobj a,int ThrdCnt)
+	{
+		this.a = a;
+		this.ThrdCnt = ThrdCnt;
+		this.start();
+	}
+
+	public void run()
+	{
+		if(ThrdCnt==1||ThrdCnt==2)
+		{	
+			a.delayAndPrint(ThrdCnt);
+			a.delayAndPrint2(ThrdCnt);
+		}
+
+		if(ThrdCnt==3)
+			a.iterateArrayList();
+	}
+}

src/ThreadTest/syncmain.java

@@ -0,0 +1,22 @@
+package ThreadTest;
+
+public class syncmain {
+
+	/* Synchronsed method example */
+
+	public static void main(String s[]) throws InterruptedException
+	{
+		syncobj obj = new syncobj();
+
+		// Synchronised method example
+		new ThreadCreator(obj,1).join();
+		new ThreadCreator(obj,2).join();
+
+		// ConcrrentModificationException creator
+		new ThreadCreator(obj,3);
+		Thread.sleep(2000);  // wait till the object is started to iterate
+		System.out.println("adding to arraylist");
+		obj.al.add(3);
+	}
+
+}

src/ThreadTest/syncobj.java

@@ -0,0 +1,65 @@
+package ThreadTest;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+
+public class syncobj {
+
+	ArrayList al = new ArrayList();
+
+	syncobj()
+	{
+		al.add(1);
+	}
+
+	synchronized void delayAndPrint(int cnt)
+	{
+		try{
+		System.out.print("Thread:"+cnt+",Mehod:1-Am in");
+		Thread.sleep(2000);
+		System.out.println(", After 2 min out");
+		}
+		catch(Exception e)
+		{
+			System.out.println("Error-"+e);
+		}
+	}
+
+	synchronized void delayAndPrint2(int cnt)
+	{
+		try{
+		System.out.print("Thread:"+cnt+",Mehod:2-Am in");
+		Thread.sleep(2000);
+		System.out.println(", After 2 min out");
+		}
+		catch(Exception e)
+		{
+			System.out.println("Error-"+e);
+		}
+	}
+
+	void iterateArrayList() 
+	{
+		try
+		{
+			System.out.println("starting iterate");
+			Iterator b= al.iterator();
+			while(b.hasNext())
+			{
+				try 
+				{
+					Thread.sleep(5000);
+					b.next();
+				} catch (InterruptedException e) 
+				{
+					System.out.println(e);
+				}
+			}
+			System.out.println("ending iterate");
+		}
+		catch(Exception e)
+		{
+			System.out.println(e);
+		}
+	}
+}