Added example of Method Reference for a super method of a particular object and fixed for instance method of an arbitrary object of a particular type.

core-java-8/src/main/java/com/baeldung/doublecolon/Computer.java

@@ -44,6 +44,18 @@ public class Computer {
         this.healty = healty;
     }
 
+    public void turnOnPc() {
+        System.out.println("Computer turned on");
+    }
+
+    public void turnOffPc() {
+        System.out.println("Computer turned off");
+    }
+
+    public Double calculateValue(Double initialValue) {
+        return initialValue/1.50;
+    }
+
     @Override
     public String toString() {
         return "Computer{" + "age=" + age + ", color='" + color + '\'' + ", healty=" + healty + '}';

core-java-8/src/main/java/com/baeldung/doublecolon/MacbookPro.java

@@ -0,0 +1,35 @@
+package com.baeldung.doublecolon;
+
+import java.util.function.Function;
+
+
+public class MacbookPro extends Computer{
+
+    public MacbookPro(int age, String color) {
+        super(age, color);
+    }
+
+    public MacbookPro(Integer age, String color, Integer healty) {
+        super(age, color, healty);
+    }
+
+    @Override
+    public void turnOnPc() {
+        System.out.println("MacbookPro turned on");
+    }
+
+    @Override
+    public void turnOffPc() {
+        System.out.println("MacbookPro turned off");
+    }
+
+    @Override
+    public Double calculateValue(Double initialValue){
+
+        Function<Double,Double> function = super::calculateValue;
+        final Double pcValue = function.apply(initialValue);
+        System.out.println("First value is:" +pcValue);
+        return pcValue + (initialValue/10) ;
+
+    }
+}