public void setName(String name) { vehicleName = name; } public String toString() { return vehicleName; } ublic class Boat extends Vehicle { private int numEngines; public Boat(int num) { numEngines = num; } public String toString() { noturn Sunon toString() 11 11 numEnginos:
public void setName(String name) { vehicleName = name; } public String toString() { return vehicleName; } ublic class Boat extends Vehicle { private int numEngines; public Boat(int num) { numEngines = num; } public String toString() { noturn Sunon toString() 11 11 numEnginos:
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
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Constructor
The easiest way to think of a constructor in object-oriented programming (OOP) languages is:
Question
![### Question 11
**What is output?**
```java
public class Vehicle {
protected String vehicleName;
public void setName(String name) {
vehicleName = name;
}
public String toString() {
return vehicleName;
}
}
public class Boat extends Vehicle {
private int numEngines;
public Boat(int num) {
numEngines = num;
}
public String toString() {
return super.toString() + " " + numEngines;
}
}
Boat fastBoat = new Boat(2);
fastBoat.setName("Firebird");
System.out.println(fastBoat);
```
**Options:**
- Firebird
- Boat@f35a442b
- Firebird 2
- Syntax error
### Explanation:
This Java code consists of two classes: `Vehicle` and `Boat`, where `Boat` is a subclass of `Vehicle`. Let's break down the code:
1. **Class Vehicle:**
- **Protected String `vehicleName`:** This variable can be accessed within its class and by subclasses.
- **Method `setName(String name)`:** Sets the `vehicleName` to the provided string `name`.
- **Method `toString()`:** Returns the `vehicleName`.
2. **Class Boat:**
- **Private int `numEngines`:** This variable stores the number of engines of the boat.
- **Constructor `Boat(int num)`:** Initializes `numEngines` with the provided integer `num`.
- **Method `toString()`:** Overrides the `toString()` method of the `Vehicle` class. It returns a string that concatenates the result of `super.toString()`, which is the `vehicleName` from the `Vehicle` class, a space, and `numEngines`.
3. **Object Creation and Method Calls:**
- A `Boat` object `fastBoat` is created with `2` engines.
- The `setName` method of the `Vehicle` class is called to set the `vehicleName` to `"Firebird"`.
- `System.out.println(fastBoat)` implicitly calls the `toString()` method of the `fastBoat` object.
Since `fastBoat`'s `toString()` method returns `vehicleName` + " " + `numEngines`, the output will be:
**](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F5498129d-fa90-4054-9767-1cffe54599e5%2Fb26dae5f-bc62-4fdb-b800-475609e42614%2Ffz85my_processed.jpeg&w=3840&q=75)
Transcribed Image Text:### Question 11
**What is output?**
```java
public class Vehicle {
protected String vehicleName;
public void setName(String name) {
vehicleName = name;
}
public String toString() {
return vehicleName;
}
}
public class Boat extends Vehicle {
private int numEngines;
public Boat(int num) {
numEngines = num;
}
public String toString() {
return super.toString() + " " + numEngines;
}
}
Boat fastBoat = new Boat(2);
fastBoat.setName("Firebird");
System.out.println(fastBoat);
```
**Options:**
- Firebird
- Boat@f35a442b
- Firebird 2
- Syntax error
### Explanation:
This Java code consists of two classes: `Vehicle` and `Boat`, where `Boat` is a subclass of `Vehicle`. Let's break down the code:
1. **Class Vehicle:**
- **Protected String `vehicleName`:** This variable can be accessed within its class and by subclasses.
- **Method `setName(String name)`:** Sets the `vehicleName` to the provided string `name`.
- **Method `toString()`:** Returns the `vehicleName`.
2. **Class Boat:**
- **Private int `numEngines`:** This variable stores the number of engines of the boat.
- **Constructor `Boat(int num)`:** Initializes `numEngines` with the provided integer `num`.
- **Method `toString()`:** Overrides the `toString()` method of the `Vehicle` class. It returns a string that concatenates the result of `super.toString()`, which is the `vehicleName` from the `Vehicle` class, a space, and `numEngines`.
3. **Object Creation and Method Calls:**
- A `Boat` object `fastBoat` is created with `2` engines.
- The `setName` method of the `Vehicle` class is called to set the `vehicleName` to `"Firebird"`.
- `System.out.println(fastBoat)` implicitly calls the `toString()` method of the `fastBoat` object.
Since `fastBoat`'s `toString()` method returns `vehicleName` + " " + `numEngines`, the output will be:
**
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