无法使用Eclipse自动生成equals方法

Question

I'm using eclipse to write my Java programs now, but I need to override the equals method so it will take the actual data and not the name or id. When I try to auto-generate it the way I know, it says I have no non-static variables. I added some in and it still doesn't work. I don't know enough about Java to do it myself, but I know enough that I would most likely understand what you are talking about. (I'm not done with my code, I just started. The integers x and y were just to try to make it work.)

package mainPackage;
import java.util.*;

public class Main extends Creater {
    public static void main(String[] args) {
        int x = 0;
        int y = 0;
        thatInput = Inputs.ask();
        Loops.CreateArray();
    }
}

Answer 1

The message that you have "no non-static variables" is giving you the right hint. Override the hashCode and equals methods only makes sense if there are non-static variables in the class. So if you changed your example to the following, you could implement those methods (or have them auto-generated for you by eclipse):

public class Main extends Creater {
    private int x = 0;
    private int y = 0;

    public static void main(String[] args) {
        // other code
    }

    @Override
    public boolean equals(Object obj) {
        // ... your equals code goes here
    }

    @Override
    public int hashCode() {
        // ... your hashCode, er, code goes here
    }

    // ... other code that does wonderful things with x and y
}

Note how I've moved your x and y variables to be at the class level rather than at the method level where you had them. Please also note that someone who or something that creates is a creator , not a creater , that I wouldn't recommend naming your package mainPackage , and that I wouldn't go importing java.util.* in every class just for the sake of it (if you're using eclipse, just do Ctrl + Shift + O to organise your imports).

Please also see which issues to consider when overriding these methods .

Answer 2

To automatically add equals and hashCode methods:

1. Menu -> Source -> Generate hashCode() and equals()
2. Select the fields you want make part of hashCode() and equals()
3. Click Ok

The rest will be done by eclipse.