[resolved] Convert LIST to String

[Anonymous]

Description:

My job: (Talend v5.6)


product_description field on json = ["aaa" , "bbb" , "ccc" , "dd,ee" , "ac, bd ,ef"] (***) 
Using tExtractJSONField to load (***) and check "Is Array", convert to "String, List, Object"



In tMap, I try with data type: String, List, Object ... to mapping product_description



And result after mapping =  [aaa , bbb , ccc , dd,ee , ac, bd ,ef] 

Problems:
1/ I search on google about LIST type in Talend, but can not understand .
2/ I try to make data after loading like:  
aaa 
bbb 
ccc
dd,ee 
ac, bd ,ef

Edit:
From  Talend document
--> Is Array: select this check box when the JSON field to be extracted is an array instead of an object.
But what kind of "an array" , string array  or list or array list ... 

Thanks.

[Anonymous]

I write a simple routine with input = product_description ( [color=#5b5b5d][size=1][font=Verdana, Helvetica, Arial, sans-serif][aaa , bbb , ccc , dd,ee , ac, bd ,ef] [/font][/size][/color]😞

    public static int convertToString( String input) {
    	String[] ary = input.split(","); -- this is line 38
    	return ary.length;
    }

But it gets errors:

Exception in component tMap_10
java.lang.NullPointerException
	at routines.convert_type.convertToString(convert_type.java:38)
	at  ......

 I am curious about this problem and trying to fix.

[Anonymous · Accepted solution]

I am sorry about my mistake.
Because of null value in product_description , so I got errors above. 

Here my code:

    public static String convertToString( List input) {
    String rs = "";
    try {
    for(int i = 0; i< input.size(); i++)
    {
    rs = rs + input.get(i) + "\n";
    }
} catch (Exception e) {
//System.out.println (e.getMessage());
}
return rs;
    }