Added 26 solutions

Java/Data Structures/Java Sort/Solution.java

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+//     Author: Rodney Shaghoulian
+//     Github: github.com/rshaghoulian
+// HackerRank: hackerrank.com/rshaghoulian
+
+import java.util.Scanner;
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+
+class Student{
+    private int id;
+    private String fname;
+    private double cgpa;
+    public Student(int id, String fname, double cgpa) {
+        super();
+        this.id = id;
+        this.fname = fname;
+        this.cgpa = cgpa;
+    }
+    public int getId() {
+        return id;
+    }
+    public String getFname() {
+        return fname;
+    }
+    public double getCgpa() {
+        return cgpa;
+    }
+}
+
+public class Solution {
+    public static void main(String[] args){
+        Scanner scan = new Scanner(System.in);
+        int testCases = Integer.parseInt(scan.nextLine());
+
+        List<Student> studentList = new ArrayList<Student>();
+        while (testCases-- > 0) {
+            int id       = scan.nextInt();
+            String fname = scan.next();
+            double cgpa  = scan.nextDouble();
+
+            Student st = new Student(id, fname, cgpa);
+            studentList.add(st);
+        }
+        scan.close();
+
+        Collections.sort(studentList, new StudentComparator());
+        
+        for (Student st: studentList) {
+            System.out.println(st.getFname());
+        }
+    }
+}
+
+class StudentComparator implements Comparator<Student> {
+    double epsilon = 0.001; // since we shouldn't use "==" with doubles
+    @Override
+    public int compare(Student s1, Student s2) {
+        if (Math.abs(s1.getCgpa() - s2.getCgpa()) > epsilon) {
+            return s1.getCgpa() < s2.getCgpa() ? 1 : -1; // descending order
+        } else if (!s1.getFname().equals(s2.getFname())) {
+            return s1.getFname().compareTo(s2.getFname());
+        } else {
+            return s1.getId() - s2.getId();
+        }
+    }
+}