Query on blocked state

[raja singh kumar]

Hi,

I was reading about multithreading and I came across the term "blocked state" or "blocked for I/O". Can someone tell me what is a "blocked " state and "blocked for I/O" state mean and explain with an example? Also, when does a thread enter the blocked state?

[Campbell Ritchie]

I have a KeyboardInputs class which wraps the functionality of a Scanner reading from System.in.

private int i; // must be a field
// ...
i = 1_000_000_000;
// ...
Thread t = new Thread(() -> i = KeyboardInputs.nextInt(
         "Please enter number of cows Campbell deserves for this post: "));
// ...
t.start();
System.out.printf("Campbell deserves %d cows.%n", i);

The thread in line 8 will block after the request is printed to screen until you write −999999999 because the nextXXX methods of Scanner are blocking methods. I am not sure, but I think that line 9 will print that I deserve 1000000000 cows because it is on a different thread.

[raja singh kumar]

The code prints 1000000000 but whats the point. I did not get it.