I do not understand threads plz help me

4. Implement a Java program for the scenario given below A thread thr_readl reads two integers at a time from a file input.txt and adds these numbers and displays the result to the user. Another thread thr_read2 reads the two integers from the same file input.txt and performs multiplication and displays the result to the user. Another thread thr_write writes two integers to the file input.txt. If thr_readl or thr_read2 doesn't have numbers to read from the file then it should enter the wait state. thr_write after writing the numbers should notify any thread that's waiting to perform the write operation on the file