Adding java method reference

java-8/Java-method-reference/Main.java

@@ -0,0 +1,95 @@
+import java.util.Arrays;
+import java.util.function.BiFunction;
+
+interface IStudentComparator{
+    Student getResult(Student s1,Student s2);
+}
+
+interface IStudent{
+    Student create();
+}
+
+@FunctionalInterface
+interface IStudentCreator {
+    Student createStudent(String name, int marks, String gender);
+}
+
+
+class Main{
+    public static void main(String[] args) {
+        Student[] studentArray = new Student[3];
+
+        studentArray[0] = new Student("Alex", 24, "male");
+        studentArray[1] = new Student("Liza", 22, "female");
+        studentArray[2] = new Student("Bob", 26, "male");
+
+        Arrays.sort(studentArray, (Student s1, Student s2) -> Student.compareMarks(s1,s2));
+
+        for (Student s:studentArray){
+            System.out.print(s.getName()+" ");
+        }
+
+        //static method reference
+        //example 1
+        Arrays.sort(studentArray, Student::compareMarks);
+
+        //example 2
+        BiFunction<Student,Student,Student> comparator = Student::compareMarksOfTwo;
+        Student result = comparator.apply(studentArray[0],studentArray[1]);
+        System.out.println(result.getName()+ " "+result.getMarks()+" "+result.getGender());
+
+        //example 3
+        IStudentComparator comparator1 = Student::compareMarksOfTwo;
+        Student result1 = comparator1.getResult(studentArray[0],studentArray[1]);
+        System.out.println(result1.getName()+ " "+result1.getMarks()+" "+result1.getGender());
+
+
+        //Instance method reference of a particular object
+        //example 1
+        NameComparator comparator2 = new NameComparator();
+        Arrays.sort(studentArray, comparator2::compareNames);
+
+        //example 2
+        NameComparator comparator3 = new NameComparator();
+        BiFunction<Student,Student,Student> biFunction = comparator3::compareMarks;
+        Student result2 = biFunction.apply(studentArray[0],studentArray[1]);
+        System.out.println(result2.getName()+ " "+result2.getMarks()+" "+result2.getGender());
+
+        //example 3
+        Student result4 = new NameComparator().compareMarks(studentArray[0],studentArray[1]);
+        System.out.println(result4.getName()+ " "+result4.getMarks()+" "+result4.getGender());
+
+        //example 4
+        IStudentComparator comparator4 = new NameComparator()::compareMarks;
+        Student result5 = comparator4.getResult(studentArray[0],studentArray[1]);
+        System.out.println(result5.getName()+ " "+result5.getMarks()+" "+result5.getGender());
+
+        //Instance method reference of an arbitrary object of a particular type
+        String[] nameArray = new String[3];
+        int i = 0;
+        for(Student s : studentArray){
+            nameArray[i++] = s.getName();
+        }
+
+        Arrays.sort(nameArray,String::compareTo);
+
+        //Constructor reference
+
+        //1. Constructor with no parameter
+        IStudent iStudent = Student::new;
+        Student s = iStudent.create();
+
+        System.out.println(s.getName() + " "+s.getMarks()+" "+s.getGender());
+
+        //2. constructor with two parameters
+        BiFunction<String,String,Student> biFunction1 = Student::new;
+        Student s1 = biFunction1.apply("Alex","male");
+        System.out.println(s1.getName() + " "+s1.getMarks()+" "+s1.getGender());
+
+        //Constructor with three or more than three parameters
+        IStudentCreator studentCreator2 = Student::new;
+        Student s2 = studentCreator2.createStudent("Alex",24,"male");
+        System.out.println(s2.getName() + " "+s2.getMarks()+" "+s2.getGender());
+
+    }
+}

java-8/Java-method-reference/NameComparator.java

@@ -0,0 +1,9 @@
+public class NameComparator {
+    public int compareNames(Student s1, Student s2){
+        return s1.getName().compareTo(s2.getName());
+    }
+
+    public Student compareMarks(Student s1,Student s2){
+        return s1.getMarks() > s2.getMarks() ? s1 : s2;
+    }
+}

java-8/Java-method-reference/Student.java

@@ -0,0 +1,43 @@
+class Student {
+    private String name;
+    private int marks;
+    private String gender;
+
+    Student() {
+        this.name = "none";
+        this.marks = -1;
+        this.gender = "none";
+    }
+
+    Student(String name, String gender) {
+        this.name = name;
+        this.gender = gender;
+        this.marks = -1;
+    }
+
+    Student(String name, int marks, String gender) {
+        this.name = name;
+        this.marks = marks;
+        this.gender = gender;
+    }
+
+    public static int compareMarks(Student s1, Student s2) {
+        return s1.marks - s2.marks;
+    }
+
+    public static Student compareMarksOfTwo(Student s1, Student s2) {
+        return s1.marks > s2.marks ? s1 : s2;
+    }
+
+    public int getMarks() {
+        return marks;
+    }
+
+    public String getGender() {
+        return gender;
+    }
+
+    public String getName() {
+        return name;
+    }
+}