Question

hi am storing the results in array list which are obtained by querying different database in java. i need to compare this array list to get the common rows

      List name = new  ArrayList();
      name.add(Spreadsheets.getString("Name"));

     List namedb = new  ArrayList();
     namedb .add(rs.getString("eName"))

in c++ we use strcmp to compare. but in java how do i compare this arraylist and it should return common rows. or how do i apply binary search algorithm to search these to arraylist?

Answer 1

Use the List’s retainAll method.

List<String> names = new ArrayList<String>();
List<String> namesDB =  new ArrayList<String>();

// Get some names ??
names.add(Spreadsheets.getString("Name"));

boolean hasCommonNames =  namesDB.retainAll( names );

// The namesDB will only contain the common names.
if( hasCommonNames ) {
    // Do something with the common names
}