浅谈Java由于不当的执行顺序导致的死锁

public void transferMoneyDeadLock(Account from,Account to, int amount) throws InsufficientAmountException {
    synchronized (from){
        synchronized (to){
            transfer(from,to,amount);
        }
    }
}

private void transfer(Account from,Account to, int amount) throws InsufficientAmountException {
    if(from.getBalance() < amount){
        throw new InsufficientAmountException();
    }else{
        from.debit(amount);
        to.credit(amount);
    }
}

A：transferMoneyDeadLock（accountA, accountB, 20）
B：transferMoneyDeadLock（accountB, accountA, 10）

private void transfer(Account from,Account to, int amount) throws InsufficientAmountException {
    if(from.getBalance() < amount){
        throw new InsufficientAmountException();
    }else{
        from.debit(amount);
        to.credit(amount);
    }
}

public void transferMoney(Account from,Account to, int amount) throws InsufficientAmountException {

    int fromHash= System.identityHashCode(from);
    int toHash = System.identityHashCode(to);

    if(fromHash < toHash){
        synchronized (from){
            synchronized (to){
                transfer(from,to, amount);
            }
        }
    }else if(fromHash < toHash){
        synchronized (to){
            synchronized (from){
                transfer(from,to, amount);
            }
        }
    }else{
        synchronized (lock){
        synchronized (from) {
            synchronized (to) {
                transfer(from, to, amount);
            }
            }
        }
    }
}