For Questions 1-3: consider the following code:
public class A
{
private int number;
protected String name;
public double price;
public A()
{
System.out.println(“A() called”);
}
private void foo1()
{
System.out.println(“A version of foo1() called”);
}
protected int foo2()
{
Sysem.out.println(“A version of foo2() called);
return number;
}
public String foo3()
{
System.out.println(“A version of foo3() called”);
Return “Hi”;
}
}//end class A
public class B extends A
{
private char service;
public B()
{
super();
System.out.println(“B() called”);
}
public void foo1()
{
System.out.println(“B version of foo1() called”);
}
protected int foo2()
{
int n = super.foo2();
System.out.println(“B version of foo2() called”);
return (n+5);
}
public String foo3()
{
String temp = super.foo3();
System.out.println(“B version of foo3()”);
return (temp+” foo3”);
}
}//end class B
public class C extends B
{
public C()
{
super();
System.out.println();
}
public void foo1()
{
System.out.println(“C version of foo1() called”);
}
}//end class C
Assignment
B b1 = new B();
B b3 = new B();
int n = b3.foo2();
//b4 is a B object reference
System.out.println(b4.foo3());
public class N extends String, Integer
{
}
When you compile, you get the following message:
N.java:1: ‘{‘ expected
public class N extends String, Integer
^
1 error
Explain what the problem is and how to fix it.
// Code to copy
A.java
public class A {
private int number;
protected String name;
public double price;
public A()
{
System.out.println("A() called");
}
private void foo1()
{
System.out.println("A version of foo1()
called");
}
protected int foo2()
{
System.out.println("A version of foo2()
called");
return number;
}
public String foo3()
{
System.out.println("A version of foo3()
called");
return "Hi";
}
}//end class A
B.java
public class B extends A
{
private char service;
public B()
{
super();
System.out.println("B() called");
}
public void foo1()
{
System.out.println("B version of foo1() called");
}
protected int foo2()
{
int n = super.foo2();
System.out.println("B version of foo2() called");
return (n+5);
}
public String foo3()
{
String temp = super.foo3();
System.out.println("B version of foo3()");
return (temp+" foo3");
}
}//end class B
C.java
public class C extends B
{
public C()
{
super();
System.out.println();
}
public void foo1()
{
System.out.println("C version of foo1() called");
}
}//end class C
B b1 = new
B();
Main.java
public class Main {
public static void main(String[] args) {
B b1 = new B();
}
}
// Screenshot of the code & output
Explanation:
When Class B object created it's constructor gets called and inside constructor super () calls super class(A) and executed first . A() called , B() Called as output.
When B b3 = new B(); int n = b3.foo2(); called
Main.java
public class Main {
public static void main(String[] args) {
B b3 = new B();
int n = b3.foo2();
}
}
// Sample output
Explanation:
Super() keyword always executes parent class constructor or methods called & executed first followed by child class.
when //b4 is a B object reference System.out.println(b4.foo3()); called:
Main.java
public class Main {
public static void main(String[] args) {
B b4 = new B();
//b4 is a B object reference
System.out.println(b4.foo3());
}
}
// Sample output
public class N extends String, Integer
{
}
Explanation:
Here String & integer are final classes , so we can't create an object of final classes.
Error Message : The type N cannot subclass the final class String
For Questions 1-3: consider the following code: public class A { private int number; protected String...
For Questions 1-3: consider the following code: public class A { private int number; protected String name; public double price; public A() { System.out.println(“A() called”); } private void foo1() { System.out.println(“A version of foo1() called”); } protected int foo2() { Sysem.out.println(“A version of foo2() called); return number; } public String foo3() { System.out.println(“A version of foo3() called”); Return “Hi”; } }//end class A public class B extends A { private char service; public B() { super(); System.out.println(“B() called”); } public...
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