Now I am developing a simple project on Java.In that I include String Builder to append and print strings on console.When I am trying to append string array into string Builder,it prints object instead of array of strings on console.any one please tell whether my try is right or wrong.
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1post your code with your storyamit bhardwaj– amit bhardwaj2014-10-07 11:22:29 +00:00Commented Oct 7, 2014 at 11:22
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what is your expected output.Yogesh Prajapati– Yogesh Prajapati2014-10-07 11:24:03 +00:00Commented Oct 7, 2014 at 11:24
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3 Answers
- Add
Arrays.toString(yourArray)if you want to add the representation of yourStringarray. - If it's a multiple-dimension array (e.g. a
String[][]), then addArrays.deepToString(yourArray)to yourStringBuilder. - Adding the
arrayitself will add the defaultStringrepresentation. - Finally, if you need control over how you represent your
arraytoString, you'll need to iterate the elements yourself and add them to theStringBuilderin a customized format.
Edit
As a side-note, to make this work with arrays of custom Objects, you'll probably want to override the Object.toString method, otherwise your elements will be printed with the default String representation of Object (i.e. this).
6 Comments
Mena
@Nithya you're welcome! Also see my edit on custom
Objects.
Ashok M A
is it possible to ignore the '[' and ']' during this
Arrays.toString()? Because, am trying to append the elements from String[] to StringBuilder that has some elements already and I do not want to include a [ and ] in between.Mena
@AshokMA you can just remove the 1st and last character, that will consistently remove the square brackets in a one-dimensional array. For multi-dimensional arrays, you probably need to keep them, lest you want to flatten it (in which case, replace any occurrence of the square brackets with empty strings).
Ashok M A
@Mena yes I can do that. But, I am afraid that it will make my code ugly :( However, I found
Apache Commons Lang StringUtils#join() very useful in this case. :)Mena
@AshokMA arguably a little and safe string manipulation should be better than adding a dependency to your project, but it really depends on the context.
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Array is an Object. Do not directly append the array. Just iterate on array and append each element of array to your String builder.
for(String str : arr) {
builder.append(str);
}
Comments
/**
* <p>Joins the elements of the provided array into a single String
* containing the provided list of elements.</p>
*
* <p>No delimiter is added before or after the list.
* A <code>null</code> separator is the same as an empty String ("").
* Null objects or empty strings within the array are represented by
* empty strings.</p>
*
* <pre>
* StringUtils.join(null, *) = null
* StringUtils.join([], *) = ""
* StringUtils.join([null], *) = ""
* StringUtils.join(["a", "b", "c"], "--") = "a--b--c"
* StringUtils.join(["a", "b", "c"], null) = "abc"
* StringUtils.join(["a", "b", "c"], "") = "abc"
* StringUtils.join([null, "", "a"], ',') = ",,a"
* </pre>
*
* @param array the array of values to join together, may be null
* @param separator the separator character to use, null treated as ""
* @param startIndex the first index to start joining from. It is
* an error to pass in an end index past the end of the array
* @param endIndex the index to stop joining from (exclusive). It is
* an error to pass in an end index past the end of the array
* @return the joined String, <code>null</code> if null array input
*/
Apache Commons Lang StringUtils#join(). is so cool. Hope this helps.