Java String operation - Writing efficient code

Question

First of all, I am not a experienced java developer. The problem is My sql query give return data like this ABC BCD DEF EFG. But, I want to add , after the every entry So, I was tried with this

if (cursor != null) {
            cursor.moveToFirst();
            do {

                if (cursor.getPosition() == 0) {

                    getName = cursor.getString(cursor.getColumnIndexOrThrow("NAME"));

                } else {

                    getName = getName + ","
                            + cursor.getString(cursor.getColumnIndexOrThrow("NAME"));
                }

            } while (cursor.moveToNext());
        }

My question is is it okay or is there any way to write this code efficiently(Like achiving the same goal by writing less line of code). Thank you.

Isn't that code doing the opposite of what you actually want? — Rohit Jain
– Rohit Jain, Commented Aug 28, 2013 at 16:15
I mean, your code currently will add comma after all the elements except the first. But you want the opposite. Add comma only after first element. Check to see whether your current code is working fine. — Rohit Jain
– Rohit Jain, Commented Aug 28, 2013 at 16:18
@RohitJain May be you didn't get me. Please check my last comment. That's the format I want. — user2579475
– user2579475, Commented Aug 28, 2013 at 16:19

Pete B. · Accepted Answer · 2013-08-28 16:55:30Z

1

How about this:

myString = "ABC BCD DEF EFG";
String newString = myString.replace(" ", ", ");
System.out.println(newString);

Output:

ABC, BCD, DEF, EFG

edited Aug 28, 2013 at 16:55

answered Aug 28, 2013 at 16:17

Pete B.

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2 Comments

StormeHawke Over a year ago

Reading his comments, I think he would want replaceAll, but this is the best answer to achieve what he's asking for IMO so +1

Moob Over a year ago

I think the 'ABC','BCD' etc are just examples. The actual string may contain spaces that shouldn't be replaced.

Community · Accepted Answer · 2017-05-23 11:49:51Z

0

How about including the comma using the MySql query itself? You can find more about it in this link.

edited May 23, 2017 at 11:49

CommunityBot

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answered Aug 28, 2013 at 16:19

Ramesh

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Comments

Mirco Widmer · Accepted Answer · 2013-08-28 16:20:52Z

0

The following code would be shorter and should achieve the exact same thing you posted.

if (cursor != null) {
    cursor.moveToFirst();
    getName = cursor.getString(cursor.getColumnIndexOrThrow("NAME"));
    while (cursor.moveToNext()) {
        getName = getName + "," + cursor.getString(cursor.getColumnIndexOrThrow("NAME"));
    }
}

answered Aug 28, 2013 at 16:20

Mirco Widmer

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Comments

Saj · Accepted Answer · 2013-08-28 16:22:48Z

0

How about-

String str = "ABC BCD DEF EFG";
str = str.replaceFirst(" ", ", ");
System.out.println(str);

Output:

ABC, BCD DEF EFG

answered Aug 28, 2013 at 16:22

Saj

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Comments

Moob · Accepted Answer · 2013-08-28 16:23:48Z

0

You can do it in less code but its probably no more efficient:

if (cursor != null) {
    cursor.moveToFirst();
    while(cursor.moveToNext()) {
        getName += ((!"".equals(getName))?",":"") + cursor.getString(cursor.getColumnIndexOrThrow("NAME"));
    } 
}

Depending on your requirements you could use a concat in the actual query.

answered Aug 28, 2013 at 16:23

Moob

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Comments

Rob · Accepted Answer · 2013-08-28 16:23:52Z

0

Your code will be a bit more efficient if you use StringBuilder rather than String when building up your result.

StringBuilder str = new StringBuilder();
loop...
    if (first) {
        str.append(cursor.getString(...));
    } else {
        str.append(',');
        str.append(cursor.getString(...));
    }
String theString = str.toString();

Every time you use + with strings, behind the scene you are creating temporary objects that need to be garbage collected. By explicitly using a StringBuilder you completely avoid extra objects to build your string in each iteration of your loop.

answered Aug 28, 2013 at 16:23

Rob

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Comments

sjdutta · Accepted Answer · 2013-08-28 16:47:48Z

0

I would like to point out one issue in your code ( not related to the string formatting ). When the cursor points to the first record, you should always check for null.

if (cursor.moveToFirst() != null)
{
    ...
}

answered Aug 28, 2013 at 16:47

sjdutta

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