Searching in a ArrayList with custom objects for certain strings

Question

I have a ArrayList with custom objects. I want to search inside this ArrayList for Strings.

The class for the objects look like this:

public class Da         


        

Answer 1

UPDATE: Using Java 8 Syntax

List<DataPoint> myList = new ArrayList<>();
//Fill up myList with your Data Points

List<DataPoint> dataPointsCalledJohn = 
    myList
    .stream()
    .filter(p-> p.getName().equals(("john")))
    .collect(Collectors.toList());

If you don't mind using an external libaray - you can use Predicates from the Google Guava library as follows:

class DataPoint {
    String name;

    String getName() { return name; }
}

Predicate<DataPoint> nameEqualsTo(final String name) {
    return new Predicate<DataPoint>() {

        public boolean apply(DataPoint dataPoint) {
            return dataPoint.getName().equals(name);
        }
    };
}

public void main(String[] args) throws Exception {

    List<DataPoint> myList = new ArrayList<DataPoint>();
    //Fill up myList with your Data Points

    Collection<DataPoint> dataPointsCalledJohn =
            Collections2.filter(myList, nameEqualsTo("john"));

}

Answer 2

Use Apache CollectionUtils:

CollectionUtils.find(myList, new Predicate() {
   public boolean evaluate(Object o) {
      return name.equals(((MyClass) o).getName());
   }
}

Answer 3

Probably something like:

ArrayList<DataPoint> myList = new ArrayList<DataPoint>();
//Fill up myList with your Data Points

//Traversal
for(DataPoint myPoint : myList) {
    if(myPoint.getName() != null && myPoint.getName().equals("Michael Hoffmann")) {
        //Process data do whatever you want
        System.out.println("Found it!");
     }
}

Answer 4

String string;
for (Datapoint d : dataPointList) {    
   Field[] fields = d.getFields();
   for (Field f : fields) {
      String value = (String) g.get(d);
      if (value.equals(string)) {
         //Do your stuff
      }    
   }
}

Answer 5

try this

ArrayList<Datapoint > searchList = new ArrayList<Datapoint >();
String search = "a";
int searchListLength = searchList.size();
for (int i = 0; i < searchListLength; i++) {
if (searchList.get(i).getName().contains(search)) {
//Do whatever you want here
}
}

Answer 6

contains() method just calls equals() on ArrayList elements, so you can overload your class's equals() based on the name class variable. Return true from equals() if name is equal to the matching String. Hope this helps.