Useful programming with Java collections

String output = names.stream()
      .sorted((name1, name2) -> {
      String[] parts1 = name1.break up(" ");
      String lastName1 = parts1[parts1.length - 1];
      String[] parts2 = name2.break up(" ");
      String lastName2 = parts2[parts2.length - 1];
      return lastName2.compareTo(lastName1);
    })
    .map(identify -> {
      String[] elements = identify.break up(" ");
      return elements[parts.length - 1];
    })
    .filter(lastName -> lastName.size() >= 5)
    .cut back("", (accumulator, factor) -> accumulator + factor + ", ");

    System.out.println("outcome: " + output);

This can concatenate all of the strings collectively, joined by a comma. (We’ll have a trailing comma that we may drop off the top.)

cut back offers us an fascinating take a look at a barely extra superior space of streams. Think about when you needed to rely the string characters and return an integer worth. How may you try this? The return worth of cut back would wish to be an integer, however the accumulator and factor args are strings. I’ll go away that for an train, with this Stack Overflow query as one lead, and my introduction to Java stream gatherers as one other.

Reusing operations

We’ve had a fairly good take a look at the way in which it feels to make use of and compose among the most necessary Java useful operations. One other necessary aspect is code reuse. Say you wanted to make use of that fancy string sorter in a number of locations. In Java, we may create a useful interface to share that operation: