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java function for arrays like phps join


java function for arrays like phps join  using -'java,php,arrays,join'

asked Sep 10, 2015 by JessikaWoodf
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19 Answers

0 votes

Apache Commons Lang has a StringUtils class which has a join function which will join arrays together to make a String.

For example:

StringUtils.join(new String[] {"Hello", "World", "!"}, ", ")

Generates the following String:

Hello, World, !
answered Sep 10, 2015 by FosterElder
0 votes

If you were looking for what to use in android, it is:

String android.text.TextUtils.join(CharSequence delimiter, Object[] tokens)

for example:

String joined = TextUtils.join(";", MyStringArray);
answered Sep 10, 2015 by LavadaHeneye
0 votes

You could easily write such a function in about ten lines of code:

String combine(String[] s, String glue)
{
  int k = s.length;
  if ( k == 0 )
  {
    return null;
  }
  StringBuilder out = new StringBuilder();
  out.append( s[0] );
  for ( int x=1; x < k; ++x )
  {
    out.append(glue).append(s[x]);
  }
  return out.toString();
}
answered Sep 10, 2015 by RegenaOIBhwu
0 votes

In Java 8 you can use

1) Stream API :

String[] a = new String[] {"a", "b", "c"};
String result = Arrays.stream(a).collect(Collectors.joining(", "));

2) new String.join method: a/21756398/466677

3) java.util.StringJoiner class: http://docs.oracle.com/javase/8/docs/api/java/util/StringJoiner.html

answered Sep 10, 2015 by KriVWMH
0 votes

A little mod instead of using substring():

//join(String array,delimiter)
public static String join(String r[],String d)
{
        if (r.length == 0) return "";
        StringBuilder sb = new StringBuilder();
        int i;
        for(i=0;i
answered Sep 10, 2015 by DenPollock
0 votes

Google guava's library also has this kind of capability. You can see the String[] example also from the API.

As already described in the api, beware of the immutability of the builder methods.

It can accept an array of objects so it'll work in your case. In my previous experience, i tried joining a Stack which is an iterable and it works fine.

Sample from me :

Deque nameStack = new ArrayDeque<>();
nameStack.push("a coder");
nameStack.push("i am");
System.out.println("|" + Joiner.on(' ').skipNulls().join(nameStack) + "|");

prints out : |i am a coder|

answered Sep 10, 2015 by MohGrahamsl
0 votes

If you are using the Spring Framework then you have the StringUtils class:

import static org.springframework.util.StringUtils.arrayToDelimitedString;

arrayToDelimitedString(new String[] {"A", "B", "C"}, "\n");
answered Sep 10, 2015 by CaitlynLansf
0 votes

Given:

String[] a = new String[] { "Hello", "World", "!" };

Then as an alternative to coobird's answer, where the glue is ", ":

Arrays.asList(a).toString().replaceAll("^\\[|\\]$", "")

Or to concatenate with a different string, such as " & ".

Arrays.asList(a).toString().replaceAll(", ", " & ").replaceAll("^\\[|\\]$", "")

However... this one ONLY works if you know that the values in the array or list DO NOT contain the character string ", ".

answered Sep 10, 2015 by LemZij
0 votes

As with many questions lately, Java 8 to the rescue:


Java 8 added a new static method to java.lang.String which does exactly what you want:

public static String join(CharSequence delimeter, CharSequence... elements);

Using it:

String s = String.join(", ", new String[] {"Hello", "World", "!"});

Results in:

"Hello, World, !"
answered Sep 10, 2015 by ReeRich
0 votes

Not in core, no. A search for "java array join string glue" will give you some code snippets on how to achieve this though.

e.g.

public static String join(Collection s, String delimiter) {
    StringBuffer buffer = new StringBuffer();
    Iterator iter = s.iterator();
    while (iter.hasNext()) {
        buffer.append(iter.next());
        if (iter.hasNext()) {
            buffer.append(delimiter);
        }
    }
    return buffer.toString();
}
answered Sep 10, 2015 by MagnoliaTEPO
0 votes

This is how I do it.

private String join(String[] input, String delimiter)
{
    StringBuilder sb = new StringBuilder();
    for(String value : input)
    {
        sb.append(value);
        sb.append(delimiter);
    }
    int length = sb.length();
    if(length > 0)
    {
        // Remove the extra delimiter
        sb.setLength(length - delimiter.length());
    }
    return sb.toString();
}
answered Sep 10, 2015 by MelvinaAylwa
0 votes

If you've landed here looking for a quick array-to-string conversion, try Arrays.toString().

Creates a String representation of the Object[] passed. The result is surrounded by brackets ("[]"), each element is converted to a String via the String.valueOf(Object) and separated by ", ". If the array is null, then "null" is returned.

answered Sep 10, 2015 by FraKerr
0 votes

Just for the "I've the shortest one" challenge, here are mines ;)

Iterative:

public static String join(String s, Object... a) {
    StringBuilder o = new StringBuilder();
    for (Iterator i = Arrays.asList(a).iterator(); i.hasNext();)
        o.append(i.next()).append(i.hasNext() ? s : "");
    return o.toString();
}


Recursive:

public static String join(String s, Object... a) {
    return a.length == 0 ? "" : a[0] + (a.length == 1 ? "" : s + join(s, Arrays.copyOfRange(a, 1, a.length)));
}
answered Sep 10, 2015 by AmpPWNM
0 votes

A similar alternative

/**
 * @param delimiter 
 * @param inStr
 * @return String
 */
public static String join(String delimiter, String... inStr)
{
    StringBuilder sb = new StringBuilder();
    if (inStr.length > 0)
    {
        sb.append(inStr[0]);
        for (int i = 1; i < inStr.length; i++)
        {
            sb.append(delimiter);                   
            sb.append(inStr[i]);
        }
    }
    return sb.toString();
}
answered Sep 10, 2015 by ShaPemberto
0 votes

Do you like my 3-lines way using only String class's methods?

static String join(String glue, String[] array) {
    String line = "";
    for (String s : array) line += s + glue;
    return (array.length == 0) ? line : line.substring(0, line.length() - glue.length());
}
answered Sep 10, 2015 by SheenaMeudel
0 votes

My spin.

public static String join(Object[] objects, String delimiter) {
  if (objects.length == 0) {
    return "";
  }
  int capacityGuess = (objects.length * objects[0].toString().length())
      + ((objects.length - 1) * delimiter.length());
  StringBuilder ret = new StringBuilder(capacityGuess);
  ret.append(objects[0]);
  for (int i = 1; i < objects.length; i++) {
    ret.append(delimiter);
    ret.append(objects[i]);
  }
  return ret.toString();
}

public static String join(Object... objects) {
  return join(objects, "");
}
answered Sep 10, 2015 by FFVUta
0 votes

There is simple shorthand technique I use most of the times..

String op = new String;
for (int i : is) 
{
    op += candidatesArr[i-1]+",";
}
op = op.substring(0, op.length()-1);
answered Sep 10, 2015 by MerCalderon
0 votes

I do it this way using a StringBuilder:

public static String join(String[] source, String delimiter) {
    if ((null == source) || (source.length < 1)) {
        return "";
    }

    StringBuilder stringbuilder = new StringBuilder();
    for (String s : source) {
        stringbuilder.append(s + delimiter);
    }
    return stringbuilder.toString();
} // join((String[], String)
answered Sep 10, 2015 by RobDalrympl
0 votes

java.util.Arrays has an 'asList' method. Together with the java.util.List/ArrayList API this gives you all you need:;

private static String[] join(String[] array1, String[] array2) {

    List list = new ArrayList(Arrays.asList(array1));
    list.addAll(Arrays.asList(array2));
    return list.toArray(new String[0]);
}
answered Sep 10, 2015 by ThaddeusSpad

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