CODEWITHSUNDEEP
javasqlsqlitearraylist
Hnr. Snd.
Hnr. Snd.

Reputation: 33

ResultSet and ArrayList of objects not working

I am basically trying to retrieve to an ArrayList something i stored in my database. I iterate through ResultSet but it I get a NullPointerException.

ResultSet rs = null;
ArrayList<People> peoList=null;

try {
    rs = stat.executeQuery("SELECT * from people WHERE surname='"+surname+"'");
} 
catch (SQLException ex) {
    Logger.getLogger(myClass.class.getName()).log(Level.SEVERE, null, ex);
}
String name, surname;
try {
    while (rs.next()) {
        name = rs.getString("name");
        surname = rs.getString("surname");

        People peo = new People(name,surname);
        peoList.add(peo);
    }
} 
catch (SQLException ex) {
    Logger.getLogger(myClass.class.getName()).log(Level.SEVERE, null, ex);
} 
return peoList;

When I call this function, a NullPinterException arises with a ton of other messages. I really don't get this. It seems that the problem is where I put peoList.add(peo);. For example, if remove this and put a counter the number of iterations is ok.

Upvotes: 2

Views: 109

Answers (1)

SnakeDoc
SnakeDoc

Reputation: 14381

while(rs.next())
{
    name = records.getString("name");
    surname = records.getString("surname");

    People peo= new People(name,surname);
    peoList.add(peo);

}

Where did records come from? This is not the variable name for your ResultSet, instead you named it rs.

I think you mean to do:

while(rs.next())
{
    name = rs.getString("name");
    surname = rs.getString("surname");

    People peo= new People(name,surname);
    peoList.add(peo);

}

The exception is being thrown in your original code because name and surname are both null, as is records because it does not exist.

UPDATE:

As a comment mentioned, you appear to also not have initialized peoList.

You're code is a little difficult on the eyes, due to mixed style, etc.

I re-wrote some of it, but here's the gist (including a properly initialized peoList:

final static Logger LOG = Logger.getLogger(myClass.class.getName());

ResultSet rs = null;

try {
    rs = stat.executeQuery("SELECT * from people WHERE surname='"+surname+"'");
} catch (SQLException ex) {
    LOG.severe("", ex);
}

String name, surname;
List<People> peoList = new ArrayList<People>();

try {
    while(rs.next()) {
        name = rs.getString("name");
        surname = rs.getString("surname");

        People peo= new People(name,surname);
        peoList.add(peo);

    }
} catch (SQLException ex) {
    LOG.severe("", ex);
} 

return peoList;

Upvotes: 1

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