creating array list and passing it from one activity to another

Question

I am a student and new to programming. It might be a simple error, can anybody help me fix it.I have to pass an array list from one activity to another. In this activity i have 5 radio buttons RB1, RB2.... and i want to pass the content of news[] it to another activity called display.

public void onClick(View v) {
        String[] news;
        news = new String[5];

        news[0] = "bbc";
        news[1] = "guardian";
        news[2] = "yahoo";
        news[3] = "sky";
        news[4] = "fox news";

        final ArrayList<String> arr = new ArrayList<String>();
        if (RB1.isChecked() == true)
            arr.add(news[0]);
        if (RB2.isChecked() == true)
             arr.add(news[1]);
        if (RB3.isChecked() == true)
            arr.add(news[2]);
        if (RB4.isChecked() == true)
            arr.add(news[3]);
        if (RB5.isChecked() == true)
            arr.add(news[4]);
if (v == Done)
        {
            Button done = (Button) findViewById(R.id.DONE);
            done.setOnClickListener(new View.OnClickListener() {
                public void onClick(View view)
                {
                    Intent myIntent = new Intent(Read.this, display.class);
                    myIntent.putExtra("pass",arr);
                    startActivity(myIntent);
                }
            });
        }

the codes for next activity is as follows

                    Intent myintent = getIntent();
        String[] Array = myintent.getStringArrayExtra("pass");

        for (int i = 0; i < Array.length; i++)
            Log.v(LOG_TAG, "THE website Is :" +Array[i]);

I am geting a java.lang.NullPointerException in the above two line i.e

for (int i = 0; i < Array.length; i++)
                Log.v(LOG_TAG, "THE website Is :" +Array[i]);

can u pls tell me why ? thanks in advance

Check it out this link may be helpful... stackoverflow.com/questions/6355787/… — Uttam
– Uttam, Commented Aug 5, 2011 at 11:09
For your NullPointerException problem, the Array variable is probably null, which would happen if you didn't properly pass it in from the previous activity. Double check this with a log statement right after String[] Array = ..., something like Log.v(LOG_TAG, "Array is null? " + (Array[i] == null));. — Josh
– Josh, Commented Aug 5, 2011 at 12:42
OH! You can't pass an ArrayList<String> into myIntent.putExtra(). You need to convert your ArrayList into a String[] first. Try putExtra((String[])arr.toArray()); — Josh
– Josh, Commented Aug 5, 2011 at 12:45

Community · Accepted Answer · 2017-05-23 10:34:21Z

2

First of all, some conventions: Start names of variables lowercase, so array instead of Array. This will save you from some confusion later.

Try it as follows, from this thread:

Bundle b=new Bundle();
b.putStringArray(key, new String[]{value1, value2});
Intent i=new Intent(context, Class);
i.putExtras(b);

and

Bundle b=this.getIntent().getExtras();
String[] array=b.getStringArray(key);

edited May 23, 2017 at 10:34

CommunityBot

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answered Aug 5, 2011 at 11:03

nhaarman

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Comments

Vineet Shukla · Accepted Answer · 2011-08-05 11:05:16Z

1

Use Bundle like this:

Bundle bundle = new Bundle();
bundle.putStringArray(key, news);
myIntent.putExtra("pass",bundle);
startActivity(myIntent);

answered Aug 5, 2011 at 11:05

Vineet Shukla

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3 Comments

Divya Over a year ago

Thanks a lot for your help . Really appreciate it . Am afraid it dosent help me solve the java.lang.NullPointerException error. Can u pls help me how to solve this error.

Vineet Shukla Over a year ago

are you still getting the java.lang.NullPointerException error..Explain where are you getting it.......

Divya Over a year ago

please see the last part of the question.. the same point.. in the for loop.. can u please tell me what difference will it make if i pass arraylist to the 2nd activity without using bundle , using just intent as i did initially...

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