System.out.println 的时间复杂度是多少？

Question

Suppose code like this:

String[] arr = {"Cat", "Dog", "Maple", "Blue"};

for (String str : arr) {
    System.out.println(str);
}

Would the time complexity be O(N) in this case or O(N^2)?

At the first glance, it seems O(N) but I thought about it and since str is not constant, It's O(N^2) in this case?

Answer 1

The time complexity for the for loop will be O(n) where n is the size of the array.

The System.out.println() take O(k) time to print k characters the average time complexity of the above piece of code should be O(nk) ;

The System.out.println internally uses the following code:

public void write(String str, int off, int len) throws IOException {
    synchronized (lock) {
        char cbuf[];
        if (len <= WRITE_BUFFER_SIZE) {
            if (writeBuffer == null) {
                writeBuffer = new char[WRITE_BUFFER_SIZE];
            }
            cbuf = writeBuffer;
        } else {    // Don't permanently allocate very large buffers.
            cbuf = new char[len];
        }
        str.getChars(off, (off + len), cbuf, 0);
        write(cbuf, 0, len);
    }
}