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Start your free trialkalyada leosrisook
Courses Plus Student 17,855 PointsHow do we fix the " is not abstract and does not override abstract method compareTo(Object)" error?
hi, I was trying to override the compareTo method in java, I added the implements word on the class title and put the @Override sign above the method I want to override and I got the " is not abstract and does not override abstract method compareTo(Object)" error message. I want to know how to fix this. Could anyone here help me out ? thanks!
package com.example;
import java.util.Date;
public class BlogPost implements Comparable {
private String mAuthor;
private String mTitle;
private String mBody;
private String mCategory;
private Date mCreationDate;
public BlogPost(String author, String title, String body, String category, Date creationDate) {
mAuthor = author;
mTitle = title;
mBody = body;
mCategory = category;
mCreationDate = creationDate;
}
@Override
public String compareTo (Object obj)
{
//trying to make it return 1...
obj = 1;
obj2 = 0;
result = obj.compareTo(obj2);
return result;
}
public String[] getWords() {
return mBody.split("\\s+");
}
public String getAuthor() {
return mAuthor;
}
public String getTitle() {
return mTitle;
}
public String getBody() {
return mBody;
}
public String getCategory() {
return mCategory;
}
public Date getCreationDate() {
return mCreationDate;
}
}
1 Answer
andren
28,558 PointsWhen you get compiler errors it's worth taking a look at all of them and not just the first that pops up if that is not helpful, the second error in the compiler for your code is this:
./com/example/BlogPost.java:45: error: compareTo(Object) in BlogPost cannot implement compareTo(T) in Comparable
public String compareTo (Object obj)
^
return type String is not compatible with int
where T is a type-variable:
T extends Object declared in interface Comparable
That errors message contains a lot of complicated stuff, but one line in particular is actually pretty straight forward, namely return type String is not compatible with int
. This is an error message that points out that your method has a return type of String while the method you are trying to override has a return type of int.
That is the main issue with your code, the method has the wrong return type, as you are not returning a String but an int. It's also worth noting though that you use two variables in your method (obj2
and result
) that are not actually declared anywhere, which means that they would have produced an error as well.
In order to return 1 you don't need to do anything beyond literally returning 1 like this:
@Override
public int compareTo (Object obj)
{
return 1;
}