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 Datapoint implements Serializable {    private String stateBased;   private String name;   private String priority;   private String mainNumber;   private String groupadress;   private String dptID;    public Datapoint(){   }    public String getMainNumber() {     return mainNumber;   }    public void setMainNumber(String mainNumber) {     this.mainNumber = mainNumber;   }    public String getName() {     return name;   }    ..and so on 

I know how to search for a string in a ArrayList but how to do that in a ArrayList with my custom objects:

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

So I want to have a function to search in my ArrayList with for example five objects for all "name" strings.

Answer 1

The easy way is to make a for where you verify if the atrrtibute name of the custom object have the desired string

    for(Datapoint d : dataPointList){         if(d.getName() != null && d.getName().contains(search))            //something here     } 

I think this helps you.

Answer 2

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"));  }