Consider the following implementation of the _compareTo() method for _String. How does the second line help with efficiency?

public int compareTo(String that) { if (this == that) return 0; // this line int n = Math.min(this.length(), that.length()); for (int i = 0; i < n; i++) {

if (this.charAt(i) < that.charAt(i)) return -1; else if (this.charAt(i) > that.charAt(i)) return +1;

}

return this.length() - that.length();