Convert String[] to comma separated string in java

i have one String[]

String[] name = {"amit", "rahul", "surya"};

i want to send name as parameter in sql query inside IN clause so how do i convert into a format

'amit','rahul','surya'

Either write a simple method yourself, or use one of the various utilities out there.

Personally I use apache StringUtils (StringUtils.join)

edit: in Java 8, you don't need this at all anymore:

String joined = String.join(",", name);

Android developers are probably looking for TextUtils.join

Android docs: http://developer.android.com/reference/android/text/TextUtils.html

Code:

String[] name = {"amit", "rahul", "surya"};
TextUtils.join(",",name)

Nice and simple: but java8 required!

String result = String.join(",", names);

StringBuilder sb = new StringBuilder();
for (String n : name) { 
    if (sb.length() > 0) sb.append(',');
    sb.append("'").append(n).append("'");
}
return sb.toString();

if (name.length > 0) {
    StringBuilder nameBuilder = new StringBuilder();

    for (String n : name) {
        nameBuilder.append("'").append(n.replace("'", "\\'")).append("',");
        // can also do the following
        // nameBuilder.append("'").append(n.replace("'", "''")).append("',");
    }

    nameBuilder.deleteCharAt(nameBuilder.length() - 1);

    return nameBuilder.toString();
} else {
    return "";
}

You can also use org.apache.commons.lang.StringUtils API to form a comma separated result from string array in Java.

StringUtils.join(strArr,",");

If you already have Spring Framework as a dependency, you could also use the very simple util method:

org.springframework.util.StringUtils.arrayToCommaDelimitedString(String[] array)

You could also simplify it using the Guava library:

String[] name = {"amit", "rahul", "surya"};
String str = "'" + Joiner.on(",").skipNulls().join(name)
    .replace(",", "','") + "'";

use StringBuilder and iterate over your String[], and append each String into it:

public static String convert(String[] name) { 
	StringBuilder sb = new StringBuilder();
	for (String st : name) { 
		sb.append('\'').append(st).append('\'').append(',');
	}
	if (name.length != 0) sb.deleteCharAt(sb.length()-1);
	return sb.toString();
}

Extention for prior Java 8 solution

String result = String.join(",", name);

If you need prefix or/ and suffix for array values

 StringJoiner joiner = new StringJoiner(",");
 for (CharSequence cs: name) {
     joiner.add("'" + cs + "'");
 }
 return joiner.toString();

Or simple method concept

  public static String genInValues(String delimiter, String prefix, String suffix, String[] name) {
    StringJoiner joiner = new StringJoiner(delimiter);
    for (CharSequence cs: name) {
      joiner.add(prefix + cs + suffix);
    }
    return joiner.toString();
  }

For example

For Oracle i need "id in (1,2,3,4,5)" 
then use genInValues(",", "", "", name);

But for Postgres i need "id in (values (1),(2),(3),(4),(5))"
then use genInValues(",", "(", ")", name);

You can do this with one line of code:

Arrays.toString(strings).replaceAll("[\\[.\\].\\s+]", "");

String[] name = {"amit", "rahul", "surya"};


public static String arrayToString(String array[])
{
    if (array.length == 0) return "";
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < array.length; ++i)
    {
        sb.append(",'").append(array[i]).append("'");
    }
    return sb.substring(1);
}

i use this

public static String convertToCommaSeparated(String[] strings) {
    StringBuffer sb = new StringBuffer("");
    for (int i = 0; strings != null && i < strings.length; i++) {
        sb.append(strings[i]);
        if (i < strings.length - 1) {
            sb.append(',');
        }
    }
    return sb.toString();
}

USE StringUtils.join function: E.g.

String myCsvString = StringUtils.join(myList, ",")

String[] paramIdIdList={"P001","P002","P003"};

StringBuilder builder = new StringBuilder();
			for(String paramId : paramIdIdList) {
				builder.append(paramId+",");
			}
			builder.deleteCharAt(builder.length() -1);
			String paramIds = builder.toString();
System.Out.Println(paramIds );

As tempting and "cool" as the code may appear, do not use fold or reduce on large collections of strings, as these will suffer from the string concatenation problem

String[] strings = { "foo", "bar", "baz" };
Optional<String> result = Arrays.stream(strings)
        .reduce((a, b) -> String.format("%s,%s", a, b));
System.out.println(result.get());

Instead, as per other answers, use String.join() if you already have a collection, or a StringBuilder if not.

String newNameList=null;

 for(int i = name.length;i>=0;i--){
    if(newNameList==null){
        newNameList = "\'" + name[name.length - i] + "\'";
    }
    else{
        newNameList += ",\'" + name[name.length - i] + "\'";
    }
}

You may also want not to spawn StringBuilder for such simple operation. Please note that I've changed name of your array from name to names for sake of content conformity:

String[] names = {"amit", "rahul", "surya"};

String namesString = "";
int delimeters = (names.size() - 1);
for (String name : names)
    namesString += (delimeters-- > 0) ? "'" + name + "'," : "'" + name + "'";

Two lines (excluding declarations; 'finalstring' should be initially declared equal to an empty string), if you don't care a lot about vertically spacing the for() loop:

for (int i = 0; i<string_array.length; i++) {finalstring += string_array[i]+",";}
finalstring = finalstring.substring(0,finalstring.length()-1);

Two lines, you're done. :)

here is a Utility method to split an array and put your custom delimiter, using

String.replace(String,String)
Arrays.toString(Object[])

here it is :

public static String toString(String delimiter, Object[]array){
    String s = "";
    
    // split array
    if (array != null && array.length > 0) {
        s = Arrays.toString(array).replace("[", "").replace("]", "");
    }
    
    // place delimiter (notice the space in ", ")
    if(delimiter != null){
        s = s.replace(", ", delimiter);
    }
    
    return s;
}

change the second argument type to suite your array type

This would be an optimized way of doing it

StringBuilder sb = new StringBuilder();
for (String n : arr) { 
    sb.append("'").append(n).append("',");
}
if(sb.length()>0)
    sb.setLength(sbDiscrep.length()-1);
return sb.toString();

In java 8 for none string array and none primitive object (Long, Integer, ...)

List<Long> ids = Arrays.asList(1l, 2l,3l);
ids.stream().map(String::valueOf).collect(Collectors.joining(","))))

In java 8 for specific field of an objets array (example a car with 2 fields color and speed)

List<Car> cars= Cars.asList(car1, cars2,car3);
    cars.stream().map(Car::getColor).collect(Collectors.joining(","))))

Combine map with valueOf for none String field of an array of objects

This my be helpful!!!

private static String convertArrayToString(String [] strArray) {
    		StringBuilder builder = new StringBuilder();
    		for(int i = 0; i<= strArray.length-1; i++) {
    			if(i == strArray.length-1) {
    				builder.append("'"+strArray[i]+"'");
    			}else {
    				builder.append("'"+strArray[i]+"'"+",");
    			}
    		}
    		return builder.toString();
    	}