Assume two threads share a BankAccount object with balance of zero (0), and that the BankAccount class provides synchronized deposit and withdraw methods. Thread one deposits $10 ten times and, concurrently, thread two withdraws $10 ten times. Which statement regarding the balance after all thread calls is definitely true?
Public synchronized void deposit(int dollars)
{
Int newBalance = balance + dollars;
System.out.println("depositing");
Balance = newBalance;
}
Public synchronized void withdraw(int dollars)
{
Int newBalance = balance - dollars;
System.out.println("withdrawing");
Balance = newBalance;
}
A) The balance could be zero or positive.
B) The balance is zero.
C) The balance could be zero or negative.
D) The balance is positive.

Question

Quizplus · Accepted Answer

Since the deposit and withdraw methods are synchronized, only one thread can access the method at a time. This means that thread one will deposit $10 ten times before thread two can withdraw any money. Therefore, after both threads have finished, the balance will be $0 because thread one deposited $100 and thread two withdrew $100.

Assume Two Threads Share a BankAccount Object with Balance of Zero