How to ensure threads sequence?

[aqas qaqz]

Sorry if this is a stupid question. I found a solved problem in a book, but the solution doesn’t contain a source code. I can't come up with the code corresponding to the solution of the problem because I still do not understand the solution (especially the bolded text). Please can anyone propose a code that exactly meets the solution specifications (explanations are welcome). Thanks for the help.
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Solution:
Sequencing in multi-threading can be achieved by different means but you can simply use join() method of thread class to start a thread when another one is finished its execution. To ensure three threads execute you need to start the last one first e.g. T3 and then call join methods in reverse order e.g. T3 calls T2.join, and T2 calls T1.join, this ways T1 will finish first and T3 will finish last.
_____________________________________________
Problem:
There are three threads T1, T2 and T3. How do you ensure sequence T1, T2, T3 in Java?

[Jeanne Boyarsky]

In trying to write the code, you need to create the three Threads. Then you need to call start() in a specific order. Can you write that much?

[Tushar Goel]

Jeanne Boyarsky wrote:In trying to write the code, you need to create the three Threads. Then you need to call start() in a specific order. Can you write that much?

I tried to run 3 thread one after another but it doesn't make sure that it always print in same order. ex:

public class Test {

	public static void main(String[] args) {
		new Thread(new Runnable() {

			@Override
			public void run() {
				System.out.println("Printing 1");
				
			}
			
		}).start();
		
		new Thread(new Runnable() {

			@Override
			public void run() {
				System.out.println("Printing 2");
				
			}
			
		}).start();
		
		
		new Thread(new Runnable() {

			@Override
			public void run() {
				System.out.println("Printing 3");
				
			}
			
		}).start();
	}
}

Output:

Printing 2
Printing 1
Printing 3

[Chris Hurst]

public class Test {
 
    public static void main(String[] args) {
    	
        final Thread T1 = new Thread(new Runnable() {
 
            @Override
            public void run() {
                System.out.println("Starting 1");
                System.out.println("Ending 1");
            }
             
        });
         
        final Thread T2 = new Thread(new Runnable() {
 
            @Override
            public void run() {
                System.out.println("Starting 2");
                try {
					T1.join ();
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
                System.out.println("Ending 2"); 
            }
             
        });
         
         
        Thread T3 =  new Thread(new Runnable() {
 
            @Override
            public void run() {
                System.out.println("Starting 3");
                try {
					T2.join ();
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
                
                System.out.println("Ending 3"); 
            }
             
        });
        
        // Starting's are random 
        T3.start ();
        T2.start ();
        T1.start ();
        
        // Endings are always 1,2,3
    }
}

[Tushar Goel]

You have used join but i think Jeanne asked to write without using join.

[Chris Hurst]

You have used join but i think Jeanne asked to write without using join.

The question from aqas qaqz asks for the code for a solution specifically with join ...

Please can anyone propose a code that exactly meets the solution specifications

To ensure three threads execute you need to start the last one first e.g. T3 and then call join methods in reverse order e.g. T3 calls T2.join, and T2 calls T1.join, this ways T1 will finish first and T3 will finish last.