You restrict the access to only one thread at a time by preceding call( )'s definition with the keyword synchronized:
class Shared {
synchronized void call(String msg) {
System.out.println("Start" );
System.out.println(msg);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
System.out.println("Interrupted");
}
System.out.println("end");
}
}
class Caller implements Runnable {
String msg;
Shared target;
Thread t;
public Caller(Shared targ, String s) {
target = targ;
msg = s;
t = new Thread(this);
t.start();
}
public void run() {
target.call(msg);
}
}
public class Main {
public static void main(String args[]) {
Shared target = new Shared();
Caller ob1 = new Caller(target, "A");
Caller ob2 = new Caller(target, "B");
try {
ob1.t.join();
ob2.t.join();
} catch (InterruptedException e) {
System.out.println("Interrupted");
}
}
}