Java将字符串转换为整数以进行比较

Question

I am writing a compareTo method for the Comparable Interface for a specific class. I need to take two different strings and compare them and see if one holds a greater value than the other. I would normally use .compareTo() but in this case it is giving me an error and not working. This is what I have:

public int compareTo(Object o) {
    if (name < ((AccountOwnerComparable) o).name)
        return -1;
    else if (name > ((AccountOwnerComparable) o).name)
        return 1;
    else
        return 0;

}

I know I can't use the < or > but it is just to show what the scenario is.

Answer 1

You just have to do:

name.compareTo(String_to_be_compare);

compareTo

public int compareTo(Object o)

Compares this String to another Object. If the Object is a String, this function behaves like compareTo(String).

Note that:

Returns :

The value 0 if the argument is a string lexicographically equal to this string; a value less than 0 if the argument is a string lexicographically greater than this string; and a value greater than 0 if the argument is a string lexicographically less than this string. ( source )

So to your case:

public int compareTo(Object o)
{
    AccountOwnerComparable obj = (AccountOwnerComparable) o;
    return obj.name.compareTo(this.name);
}

tw: implement the comparable interface specifying what you want to compare to (usually the same type), since you did not specify anything your interface compares to anything which is odd.

Answer 2

The Comparable interface is generic . Your class declaration should probably look something like this:

class AccountOwnerComparable implements Comparable<AccountOwnerComparable> {...

Notice the AccountOwnerComparable type parameter. With this, you would have

public int compareTo(AccountOwnerComparable other) {
    return name.compareTo(other.name);
}

Answer 3

You might have missed a bracket or something while casting. Try the following piece of code.

public int compareTo(Object o) {
    if (name.compareTo(((AccountOwnerComparable) o).name) > 0) {
        System.out.println("Greater");
        return -1;
    } else if (name.compareTo(((AccountOwnerComparable) o).name) < 0) {
        System.out.println("Lesser");
        return 1;
    } else {
        System.out.println("Equal");
        return 0;
    }

}

Answer 4

Use Integer.parseInt() method. In this way you could use > or < and it is more verbose. I assume you want to compare two String objects containing numbers. Although you did not write it in the questions, the title says so.