I had this in mind:

private static String msgBuilder(Object... params) {    StringBuilder sb = new StringBuilder();    if (params.length > 0) {        sb.append(params[0]);    }    for (int i = 1; i < params.length; ++i) {        sb.append(" ").append(params[i]);    }    return sb.toString();}

The above version allows you not to hardcode the white space delimiting your tokens. Instead of saying

String msg = msgBuilder("Hello ", 5, " How ", "are ", "you");

you can say succintly

String msg = msgBuilder("Hello", 5, "How", "are", "you");

Hope that helps.

Your approach

As pointed out by the other answers, you are practically hard-coding whitespaces in your arguments, which can get non-standard easily, even in your example. Otherwise, the use ofStringBuilder is sound, although it wouldn't deal nicely with a singlenull value - thefor-each loop will fail as it implicitly tries to get anIterator for it.

Java 8

An alternative is to rely on the stream-based processing that Java 8 offers:

private static String format(Object... values) {    if (values == null) {        return "";    }    return Arrays.stream(values)                    .map(Objects::toString)                    .collect(Collectors.joining(" "));}

1. Construct aStream<Object> fromvalues usingArrays.stream(T...).
2. map() each value usingObjects.toString(Object) as amethod reference.
3. collect() the stream into aString byjoining(" ") them together.

• \$\begingroup\$Will it be as efficient as StringBuilder()\$\endgroup\$

  stux_kill

  – stux_kill

  2016-05-29 06:39:47 +00:00

  CommentedMay 29, 2016 at 6:39
• \$\begingroup\$Yes, it uses the newStringJoiner class as the underlying implementation, which in turn uses aStringBuilder.\$\endgroup\$

  h.j.k.

  – h.j.k.

  2016-05-29 07:22:21 +00:00

  CommentedMay 29, 2016 at 7:22

I just decompiled the below code in java version "1.8.0_73"and found that compiler is automatically optimizing the code for strings

            String hello = "a" + "b" + "c" + " hello " + " world ";            System.out.println("Hello World!!");            String a="a";            String b="b";            String c="c";            String d=a+b+c;            System.out.println(d);              System.out.println(a +" yo "+ b);

Code after decompiling

            String s = "abc hello  world ";            System.out.println("Hello World!!");            String s1 = "a";            String s2 = "b";            String s3 = "c";            String s4 = (new StringBuilder()).append(s1).append(s2).append(s3).toString();            System.out.println(s4);            System.out.println((new StringBuilder()).append(s1).append(" yo ").append(s2).toString());

• \$\begingroup\$Hi. Welcome to Code Review! This may be insightful, but how does it relate to the question? I.e. what changes in the posted code would you make?\$\endgroup\$

  mdfst13

  – mdfst13

  2016-05-31 11:25:16 +00:00

  CommentedMay 31, 2016 at 11:25
• \$\begingroup\$As per my understanding, the query asked was to create strings in an optimize way. e.g. while printing logs we append too many strings using +. So above method was appending the strings using StringBuilder() But when I decompiled the code the java compiler was doing this optimzation itself.\$\endgroup\$

  munish

  – munish

  2016-05-31 13:58:44 +00:00

  CommentedMay 31, 2016 at 13:58

@coderodde has a good point about eliminating the need for white space.

I'd simply do it this way:

private static String buildString(Object... values) {        if (values.length == 0) {             return "";        }        StringBuilder result = new StringBuilder();        for (Object value : values) {            result.append(' ').append(value);        }        return result.substring(1);}

• \$\begingroup\$Nice Suggestion. Thanx!\$\endgroup\$

  stux_kill

  – stux_kill

  2016-05-27 15:06:40 +00:00

  CommentedMay 27, 2016 at 15:06

• java
• strings