Replacing certain fixed String in java

Question

I have a string query which looks like this

{"query":{"bool":{"should":[{"terms":{"user.id":[#users_to_follow],"minimum_match":1}},{"terms":{"tweets":[#keywords_to_track],"minimum_match":1}}]}},"filter":{"range":{"publishedDate":{"from":#Unix_timestamp}}},"size":#sizelength}"

I am trying to replace certain strings in the query with another string using:

query.replace("#users_to_follow",usersToFollow);
query.replace("#keywords_to_track", keyworsToTrack);
query.replace("#Unix_timestamp","1325930428000" );
query.replace("#sizelength",Integer.toString(SMLApplicationProperties.ES_RESULTSET_SIZE));

However when I run this thing, it does not actually replace the given strings from query.

Manish · Accepted Answer · 2012-07-06 08:39:40Z

5

You need to understand that String class is immutable. Any operation on String returns a new String. You need to assign it back to query variable:

query = query.replace("#users_to_follow",usersToFollow); 
query = query.replace("#keywords_to_track", keyworsToTrack); 
query = query.replace("#Unix_timestamp","1325930428000" ); 
query = query.replace("#sizelength",Integer.toString(SMLApplicationProperties.ES_RESULTSET_SIZE));

answered Jul 6, 2012 at 8:39

Manish

3,9782 gold badges34 silver badges46 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

saurabh j Over a year ago

so when i do query=query.replace(); it does not returns the new changed string?

Denys Séguret · Accepted Answer · 2012-07-06 08:38:33Z

2

You need to get the result of the replace operation :

query = query.replace("#users_to_follow",usersToFollow);

That's because query.replace doesn't change the string you pass, it builds and returns a new one (string in java are immutable).

answered Jul 6, 2012 at 8:38

Denys Séguret

384k90 gold badges813 silver badges780 bronze badges

2 Comments

saurabh j Over a year ago

so i need to assign my query.replace() to a new string?

Denys Séguret Over a year ago

It IS a new String. You can use the same variable, as in my example. Simply add query = before the query.replace

cl-r · Accepted Answer · 2012-07-06 08:49:07Z

0

You can optimize (not accepted by everybody) :

String query = query.replace("#users_to_follow",usersToFollow).replace("#keywords_to_track", keyworsToTrack).replace("#Unix_timestamp","1325930428000" ).replace("#sizelength",Integer.toString(SMLApplicationProperties.ES_RESULTSET_SIZE));

answered Jul 6, 2012 at 8:49

cl-r

1,2581 gold badge13 silver badges26 bronze badges

Collectives™ on Stack Overflow

Replacing certain fixed String in java

3 Answers 3

1 Comment

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related