Question

In my project I need to store the values dynamically in a string and need to split that string with “,”. How can I do that ? Please help me..

My Code:

static ArrayList<ArrayList<String>> listhere;
ArrayList<String> arropids;
String arropids1; 


    for(int q=0;q<listhere.size();q++)
                {
                  arropids = listhere.get(q);

                  if(arropids.get(3).equals("1"))
                  {
                      arropids1 += arropids.get(0) + ","; 


                  System.out.println("arropids1"+arropids1);

                }
                } 

Answer 1

You must be getting NullPointerException as you havent initialized the String, initialize it as

String arropids1="";

It will resolve your issue, but I dont Recommend String for this task, as String is Immutable type, you can use StringBuffer for this purpose, so I recommend following code:

static ArrayList<ArrayList<String>> listhere;
ArrayList<String> arropids;

StringBuffer buffer=new StringBuffer();

    for(int q=0;q<listhere.size();q++)
                {
                  arropids = listhere.get(q);

                  if(arropids.get(3).equals("1"))
                  {
                      buffer.append(arropids.get(0));
                      buffer.append(","); 


                  System.out.println("arropids1"+arropids1);

                }
                }

and finally get String from that buffer by:

 String arropids1=buffer.toString();