How does compareTo work?

Question

I know that it compareToreturns a negative or positive result on how well one line correlates with another, but why:

public class Test {
    public static void main(String[] args) {
        String y = "ab2";
        if(y.compareTo("ac3") == -1) {
            System.out.println("Test");
        }
    }
}

true and

public class Test {
    public static void main(String[] args) {
        String y = "ab2";
        if(y.compareTo("ab3") == -1) {
            System.out.println("Test");
        }
    }
}

also right?

Answer 1

The general contract Comparable.compareTo(o)is to return

• a positive integer if it is larger than another object.
• negative integer if it is less than another.
• 0 if it is equal to another object.

In your example "ab2".compareTo("ac3") == -1, and "ab2".compareTo("ab3") == -1 means only that "ab2"is lower than "ac3"and "ab3". You cannot conclude anything regarding "ac3"and "ab3"only with these examples.

, b c ( "ab2" < "ac3") 2 3 (so "ab2" < "ab3"): Java .

Answer 2

compareTo String -1, String (, ), String ( ) . "ab2" "ab3" ( , 2 - 3), "ac3" ( b c), -1.

Answer 3

compareTo() . , "" , . :

• ab2 <ac3 (because b <c)
• ab2 <ab3 (because 2 <3)

By the way, you'd better use "<0" than "== -1" in an if statement, since the specification compareTosays that the function returns a negative number, not "-1"