string-question

[pet0etie]

hello,

is there some kind of function implemented in java to compare 2 strings,
which returns me a double with a value that measures the equality of 2
strings

let's say ...
<code>
String str1;
String str2;
double a;

str1 = "abcdef";
str2 = "abcdef";
a = str1.equality(str2);
// a = 1.000;

str1 = "abcdef";
str2 = "abccdef";
a = str1.equality(str2);
// a = 0.800;

str1 = "abcdef";
str2 = "abcccdef";
a = str1.equality(str2);
// a = 0.750;

str1 = "abcdef";
str2 = "abccef";
a = str1.equality(str2);
// a = 0.850;
</code>

or do i have to implement such a function on my own ?
i know ... maybe something that will be rarely used ... but i need something
like this

anyone who can help me or point to some functions i might need ?

thank u in advance,
pet0etie

 

[VisionSet]

is there some kind of function implemented in java to compare 2 strings,
which returns me a double with a value that measures the equality of 2
strings

String str1;
String str2;
double a;

str1 = "abcdef";
str2 = "abcdef";
a = str1.equality(str2);
// a = 1.000;

str1 = "abcdef";
str2 = "abccdef";
a = str1.equality(str2);
// a = 0.800; ....

or do i have to implement such a function on my own ?

You will have to implement it yourself.
Only you can determine the significance of e.g. 0.8 for 'partial' equality.

 

[Michael Borgwardt]

is there some kind of function implemented in java to compare 2 strings,
which returns me a double with a value that measures the equality of 2
strings

Sounds to me like you're looking for a Java implementation of the
"Levenshtein distance":
http://www.merriampark.com/ld.htm#JAVA

 

[Daniel Chirillo]

You can compare strings using compareTo(), which returns an int. A return
value of 0 indicates equality.

 

[Ann]

You can compare strings using compareTo(), which returns an int. A return
value of 0 indicates equality.

I was thinking about compareTo() also, but since the OP wants a double
s/he has to create her own compareTo() that returns a double. Now my
question is "how will the sort methods know to call the double version
instead of the int version?" Or, maybe I am a bit mixed up on this.

 

[Murray]

Sounds to me like you're looking for a Java implementation of the
"Levenshtein distance":
http://www.merriampark.com/ld.htm#JAVA

StringUtils in the Commons-Lang package also has an implementation.

http://jakarta.apache.org/commons/lang/

 

[VisionSet]

I was thinking about compareTo() also, but since the OP wants a double
s/he has to create her own compareTo() that returns a double. Now my
question is "how will the sort methods know to call the double version
instead of the int version?" Or, maybe I am a bit mixed up on this.

You cannot override a method with the same signature and a different return
type.

ie you cannot do this:

int myMethod();
double myMethod();

 

[Tony Morris]

You cannot override a method with the same signature and a different
return

type.

Yes you can.
See JSR-14 and/or J2SE 5.0 "co-variant return types".

 

[VisionSet]

Yes you can.
See JSR-14 and/or J2SE 5.0 "co-variant return types".

Okay, that is excellent - another reason to get my arse in gear and update
to 5.0

 

[Peter Kirk]

Okay, that is excellent - another reason to get my arse in gear and update
to 5.0

But remember that in this particular case you can't "override" the compareTo
method, because String is final.

 

[VisionSet]

But remember that in this particular case you can't "override" the compareTo
method, because String is final.

Of course, but you can implement a Comparator and use this for sorting.
However overloading the compareTo method will not make it executable at
runtime by Collections sorting mechanism.

 

[pet0etie]

thanks for all the reactions and good thinking ...
i examined all of the suggestions and was really pleased with the
"Levenshtein distance"-theory
i was thinking in a completely other direction but i think the offered one
looks better

again : thank u all
pet0etie-back-to-programming

 

[pet0etie]

"Levenshtein distance"-theory

as i promised earlier today i was intended to use the "levenshtein
distance"-theory to determine the similarity of 2 strings ... i just
finished the work and even with not a single error i got a perfect working
result

thanks to everybody who helped me to achieve this

greetz,
pet0etie