Sort ArrayValues Using Custom Comparator

This example demonstrates how to use the ArrayValue to store and sort a collection of Record objects using a custom approach.

It shows how to use custom Comparators to sort by different fields and criteria.

package com.northconcepts.datapipeline.examples.cookbook;

import com.northconcepts.datapipeline.core.ArrayValue;
import com.northconcepts.datapipeline.core.Record;
import com.northconcepts.datapipeline.core.ValueNode;

import java.util.Comparator;

public class SortArrayValuesUsingCustomComparator {
    public static void main(String[] args) {
        ArrayValue employees = new ArrayValue();

        employees.addValue(new Record()
            .setField("id", 105)
            .setField("firstName", "John")
            .setField("lastName", "Smith")
            .setField("salary", 75000.50)
            .setField("active", true));

        employees.addValue(new Record()
            .setField("id", 102)
            .setField("firstName", "Alice")
            .setField("lastName", "Johnson")
            .setField("salary", 85000.75)
            .setField("active", true));

        employees.addValue(new Record()
            .setField("id", 108)
            .setField("firstName", "Bob")
            .setField("lastName", "Williams")
            .setField("salary", 65000.25)
            .setField("active", false));

        employees.addValue(new Record()
            .setField("id", 101)
            .setField("firstName", "Carol")
            .setField("lastName", "Davis")
            .setField("salary", 92000.00)
            .setField("active", true));

        System.out.println("Before sort:");
        printEmployees(employees);

        // Sort by ID (integer field) in ascending order
        System.out.println("\nSorting by ID (ascending):");
        employees.sort(Comparator.comparing(node ->
            ((Record) node).getField("id").getValueAsInteger()
        ));

        printEmployees(employees);

        // Sort by last name (string field) alphabetically
        System.out.println("\nSorting by Last Name (alphabetically):");
        employees.sort(Comparator.comparing(node ->
            ((Record) node).getField("lastName").getValueAsString()
        ));

        printEmployees(employees);

        // Sort by salary (double field) in descending order
        System.out.println("\nSorting by Salary (descending):");
        employees.sort(Comparator.comparing((ValueNode node) ->
            ((Record) node).getField("salary").getValueAsDouble()
        ).reversed());

        printEmployees(employees);

        // Sort by active status (boolean field), then by last name
        System.out.println("\nSorting by Active status (active first), then by Last Name:");
        employees.sort(
            Comparator.comparing((ValueNode node) ->
                ((Record) node).getField("active").getValueAsBoolean()
            ).reversed()
            .thenComparing(node ->
                ((Record) node).getField("lastName").getValueAsString()
            )
        );

        printEmployees(employees);
    }

    private static void printEmployees(ArrayValue employees) {
        employees.forEach(node -> {
            Record rec = (Record) node;
            System.out.println("  ID: " + rec.getField("id").getValueAsInteger() +
                             ", Name: " + rec.getField("firstName").getValueAsString() + " " + rec.getField("lastName").getValueAsString() +
                             ", Salary: $" + rec.getField("salary").getValueAsDouble() +
                             ", Active: " + rec.getField("active").getValueAsBoolean());
        });
    }
}

Code walkthrough

1. An ArrayValue called employees is initialized and populated with four Record objects. Each Record represents an employee and contains fields for id, firstName, lastName, salary, and active status. The addValue method is used to add each employee Record to the array, allowing us to later manipulate or sort the collection as needed.
2. printEmployees is used to output each employee's details (ID, name, salary, and active status) to the console. It displays current state of the employee list after sorting or modifying the array.
3. Next we sort the employees using custom Comparators
   1. Sort the Records by the id field in increasing order.
   2. Sort the Records by the lastName field in alphabetical order.
   3. Sort the Records by the salary field in decreasing order.
   4. Sort the Records so that active Records come first, then sort by lastName alphabetically.

Output

Before sort:
  ID: 105, Name: John Smith, Salary: $75000.5, Active: true
  ID: 102, Name: Alice Johnson, Salary: $85000.75, Active: true
  ID: 108, Name: Bob Williams, Salary: $65000.25, Active: false
  ID: 101, Name: Carol Davis, Salary: $92000.0, Active: true

Sorting by ID (ascending):
  ID: 101, Name: Carol Davis, Salary: $92000.0, Active: true
  ID: 102, Name: Alice Johnson, Salary: $85000.75, Active: true
  ID: 105, Name: John Smith, Salary: $75000.5, Active: true
  ID: 108, Name: Bob Williams, Salary: $65000.25, Active: false

Sorting by Last Name (alphabetically):
  ID: 101, Name: Carol Davis, Salary: $92000.0, Active: true
  ID: 102, Name: Alice Johnson, Salary: $85000.75, Active: true
  ID: 105, Name: John Smith, Salary: $75000.5, Active: true
  ID: 108, Name: Bob Williams, Salary: $65000.25, Active: false

Sorting by Salary (descending):
  ID: 101, Name: Carol Davis, Salary: $92000.0, Active: true
  ID: 102, Name: Alice Johnson, Salary: $85000.75, Active: true
  ID: 105, Name: John Smith, Salary: $75000.5, Active: true
  ID: 108, Name: Bob Williams, Salary: $65000.25, Active: false

Sorting by Active status (active first), then by Last Name:
  ID: 101, Name: Carol Davis, Salary: $92000.0, Active: true
  ID: 102, Name: Alice Johnson, Salary: $85000.75, Active: true
  ID: 105, Name: John Smith, Salary: $75000.5, Active: true
  ID: 108, Name: Bob Williams, Salary: $65000.25, Active: false