How to put spaces in a stringbuilder

Question

Hello I have following method to display a promotion line when I comment a shoutbox:

public String getShoutboxUnderline(){
        StringBuilder builder = new StringBuilder();
        builder.append("watch");
        builder.append("on");
        builder.append("youtube");
        builder.append(":");
        builder.append("Mickey");
        builder.append("en");
        builder.append("de");
        builder.append("stomende");
        builder.append("drol");

        return builder.toString();
    }

But when I get it, I get watchonyoutube:mickeyendestomendedrol, which is without spaces. How do I get spaces in my Stringbuilder?

Mohammed Aouf Zouag · Accepted Answer · 2017-10-01T13:40:21.527

As of JDK 1.8, you can use a StringJoiner, which is more convenient in your case:

StringJoiner is used to construct a sequence of characters separated by a delimiter and optionally starting with a supplied prefix and ending with a supplied suffix.

StringJoiner joiner = new StringJoiner(" "); // Use 'space' as the delimiter
joiner.add("watch") // watch 
      .add("on") // watch on 
      .add("youtube") // watch on youtube
      .add(":") // etc...
      .add("Mickey")
      .add("en")
      .add("de")
      .add("stomende")
      .add("drol");

return joiner.toString();

This way, you will not need to add those spaces "manually".

Note: This solution is valid only if you're using Java 1.8 and up — Northern Pole, Oct 01 '17 at 08:18

score 7 · Answer 2 · answered Jan 26 '16 at 12:30

Just invoke builder.append(" ") at the location of your preference.

E.g.

builder
    .append("watch")
    .append(" ")
    .append("on")

...etc.

NB:

Using the fluent builder syntax here for convenience
You can also just append a space after each literal instead (save for the last one)

abdulrafique · Answer 3 · 2016-01-26T12:50:54.580

2

Cleaner way of doing it.

Create a class variable:

private static final String BLANK_SPACE=" ";

Now in you StringBuilder code ,append it where required:

StringBuilder builder = new StringBuilder();
    builder.append("watch");
    builder.append(BLANK_SPACE);
    builder.append("on");
    builder.append("youtube");
    builder.append(":");
    builder.append(BLANK_SPACE);
    builder.append("Mickey");
    builder.append("en");
    builder.append("de");
    builder.append(BLANK_SPACE);
    builder.append("stomende");
    builder.append("drol");
    System.out.println(builder.toString());

edited Jan 26 '16 at 12:50

answered Jan 26 '16 at 12:44

abdulrafique

304
1
11

2

You only write variables in capslock if they are constants. If they are you best use `private static final String BLANK_SPACE = " ";`. – LordAnomander Jan 26 '16 at 12:47

score 1 · Answer 4 · answered Jan 26 '16 at 12:46

A space is only a string containing the single character space.

So you can append it exactly as appending any other string.

    StringBuilder builder = new StringBuilder();
    builder.append("watch");
    builder.append(" ");
    builder.append("on");
    builder.append(" "); 
    // and so on

Remember also that the append method returns the StringBuilder so it is possible to join appends one after the other as follow

    StringBuilder builder = new StringBuilder();
    builder.append("watch").append(" ");
    builder.append("on").append(" "); 
    // and so on

score 0 · Answer 5 · edited Jul 03 '22 at 13:55

You can use this, it's equivalent to using StringBuilder or StringJoiner, but smaller

public class StringUnifier {

    String separator = "";
    List<String> dataList = new ArrayList<>();
    private String response = "";

    StringUnifier(String separator) {
        this.separator = separator;
    }

    StringUnifier add(String data) {
        if (!data.isEmpty()) {
            this.dataList.add(data);
        }
        return this;
    }

    @Override
    public String toString() {
        this.dataList.forEach(str -> {
            this.response += (str + this.separator);
        });
        return this.response.substring(0, this.response.length() - this.separator.length());
    }

}

MAIN

public class Main_Test {

    public static void main(String[] args) {
        StringUnifier stringUnifier = new StringUnifier(" ");
        stringUnifier.add("columna1").add("columna2").add("columna3");
        System.out.println(stringUnifier.toString());
    }
}

RUN

output:

columna1 columna2 columna3

How to put spaces in a stringbuilder

5 Answers5