Showcashing Deadlock in Java/Groovy

SimpleDeadLock.groovy

class RunnableThread implements Runnable {
    def obj1Private
    def obj2Private
    public RunnableThread(paramObj1, paramObj2) {
        obj1Private = paramObj1
        obj2Private = paramObj2
    }
    
    @Override
    public void run(){
        synchronized(obj1Private) {
            println "synchronized on obj1 " + Thread.currentThread().getName()
            Thread.sleep(1000)
            synchronized(obj2Private) {
                println "synchronized on obj2 " + Thread.currentThread().getName()
            }
        }
    }
}

def obj1 = new String("obj1")
def obj2 = new String("obj2")

def t1 = new Thread(new RunnableThread(obj1, obj2), "t1")
t1.start();
def t2 = new Thread(new RunnableThread(obj2, obj1), "t2")
t2.start()

Thread.sleep(2000);

// jstack <pid>
//Found one Java-level deadlock:
//=============================
//"t2":
//  waiting to lock monitor 0x0000000025ec3648 (object 0x000000071b72f440, a java.lang.String),
//  which is held by "t1"
//"t1":
//  waiting to lock monitor 0x000000002a38a508 (object 0x000000071b72f4e0, a java.lang.String),
//  which is held by "t2"
//
//Java stack information for the threads listed above:
//===================================================
//"t2":
//        at RunnableThread.run(SimpleDeadLock.groovy:14)
//        - waiting to lock <0x000000071b72f440> (a java.lang.String)
//        - locked <0x000000071b72f4e0> (a java.lang.String)
//        at java.lang.Thread.run(Thread.java:748)
//"t1":
//        at RunnableThread.run(SimpleDeadLock.groovy:14)
//        - waiting to lock <0x000000071b72f4e0> (a java.lang.String)
//        - locked <0x000000071b72f440> (a java.lang.String)
//        at java.lang.Thread.run(Thread.java:748)
//
//Found 1 deadlock.