Bittiger Lesson 4

bittiger java data structure

Java 8

Comparator

Lambda Expression "->"

Functional Interface predicates,comparator,runnable

Method References

Default Interface

Streams map/reduce/count/filter/flatMap/Collectors

Map

Comparator

• Comparator?

• Comparable?

• Comparator

  • int compare(T o1, T o2);
  • boolean equals(Object obj); //optional

• Comparable

  • int compareTo(T o)

Comparable

• Desctiption: A class instance is able to compare with other instance.

public class Employee implements Comparable<Employee> {
  String name;
  int age;
  @Override
  public int compareTo(Employee that) {
    return 

Comparator

• Description: a kind of class which could compare two instances.

public class AgeComparator implements Comparator<Employee> {
  @Override
  public int compare(Employee e1, Employee e2)
    return e1.getAge() - e2.getAge();
}

Lambda Expression

An anonymous function -- no name, in-line

Default Methods

Stream

Map