CODEWITHSUNDEEP
javajava-8
Deepak Shajan
Deepak Shajan

Reputation: 921

Dynamic function calling in Java 8 Streams with Predicate Object

Here is my parent class

class Parent
{
String attrib1;
String attrib2;
String attrib3;

// getters and setters of three fields

Then I created a list

List<Parent> objList = new ArrayList<Parent>();

Then I added a number of Parent objects to objList.

Now I want to filter these objects based on value of the fields in the class. But I will get field name only dynamically. I want to use streams for this purpose.

List<Parent> temp = objList.stream()
                .filter(nestedDo -> nestedDo.getAttrib2() == "manu")
                .collect(Collectors.toList());

Here getAttrib2() varies. It can be getAttrib1() or getAttrib3().

So I need dynamic function calling. Can we achieve it using Predicates. Unfortunately, I don't know anything about the Predicate object. Please explain your answer elaborately with all concepts inside it.

Upvotes: 1

Views: 1953

Answers (1)

Masudul
Masudul

Reputation: 21981

Yes, you can create different Predicate and use them based on condition.

Predicate<Parent>  first= e -> e.getAttrib1().equals("nanu"); 
Predicate<Parent>  second= e -> e.getAttrib2().equals(".."); 

List<Parent> temp = objList.stream()
            .filter(first)   // Similarly you can call second
            .collect(Collectors.toList());

Upvotes: 2

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