Predicates basically used in ios to query over model class data but from java 8 its available in android or java this function returns true or false value based on condition like P: Y? {true, false} that predicates on.

Example : We have a model class named Employee for age and salary

public class Employee {
    public Class(Integer salary, Integer age){
        msalary = salary;
        mage = age;
    }
    private Integer msalary;
    private Integer mage;
    public Integer getmsalary() {
        return msalary;
    }
    public void setmsalary(Integer msalary) {
        this.msalary = msalary;
    }
    public Integer getmage() {
        return mage;
    }
    public void setmage(Integer mage) {
        this.mage = mage;
    }
    @Override
    public String toString() {
        return this.msalary.toString()+" - "+this.mage.toString();
    }
}

Now We can create Predicates like this :

public class EmployeePredicates
{
    public static Predicate<Employee> isAgeMoreThan(Integer age) {
        return p -> p.getAge() > age;
    }
    public static List<Employee> filterEmployee (List<Employee> employee, Predicate<Employee> predicate) {
        return employee.stream().filter( predicate ).collect(Collectors.<Employee>toList());
    }
}

This function will check and return new collection list that will satisfy predicates conditions like this.

Main class to pass students objects like this :

public class TestingPredicates {
    public static void main(String[] args){
        Employee e1 = new Employee(11234,23);
        Employee e2 = new Employee(212312,13);
        Employee e3 = new Employee(31231,43);
        List<Employee> employee = new ArrayList<Employee>();
        employee.addAll(Arrays.asList(new Employee[]{e1, e2, e3}));
        System.out.println(filterEmployee(employee, isAgeMoreThan(35)));
    }
}