You are given the following abstract class:

And the following subclasses:

and:

Now if we run the following code and the user types in 'O', what is printed by the last call to System.out.println(...):

Question

You are given the following abstract class:

And the following subclasses:

and:

Now if we run the following code and the user types in 'O', what is printed by the last call to System.out.println(...):

BlackTom AI · Accepted Answer

The question provides a small Java-like scenario with an abstract class Building and two concrete subclasses, Office and House, each implementing a toString method that formats its output.

First, we identify how the program flows when the user types a character. The Run class reads a character choice and then uses conditional checks to decide which object to create:
- If choice equals 'H', a new House is created.
- Else if choice equals 'O', a new Office is created with certain parameters.
- Else if choice equals '0' (zero), a new Office is created with a different set of parameters.

Since the user typed 'O' (capital letter O), the program will execute the branch that creates a new Office object with the parameters shown for the 'O' case. In the provided code snippet, that line looks like b = new Office("100 George St", 140, 3);

Next, after the object b is created, the program checks if b is not null and then prints b. Printing an object in Java calls its toString() method.

For Office, the toString() implementation returns a string in the format:
"0: " + this.numberOfRooms + " rooms" (or possibly "O: " depending on whether the first character is a zero or the letter O in the code font). The important part is that it includes the number of rooms and the units word.

Given the Office constructed for the 'O' branch has numberOfRooms equal to 3 (as per the constructor call new Office("100 George St", 140, 3)), the toString will embed 3 in place of numberOfRooms.

Therefore, the last call to System.out.println(...) will print a line that indicates the Office with 3 rooms. If the toString uses the leading digit zero, it would print "0: 3 rooms"; if it uses the letter O, it would print "O: 3 rooms". The distinction between the digit 0 and the letter O is a code-font issue, but the numeric part (3) is what determines the number of rooms shown.

Summary of key points:
- Input 'O' selects the Office branch with 3 rooms.
- The last println prints the Office’s toString representation.
- The correct numeric value in the output is 3 rooms; the leading character is either 0 or O depending on the exact toString implementation in the code, but the number of rooms is 3.

Common confusion to watch for:
- If someone expects 8 rooms, they might be thinking of the other Office branch (the one triggered by '0'), which is not chosen when the user enters 'O'.
- The difference between the characters '0' (zero) and 'O' (capital letter o) can be visually subtle in some fonts, but they correspond to different branches in the code.

You are given the following abstract class: And the following subclasses: and: Now if we run the following code and the user types in 'O', what is printed by the last call to System.out.println(...):

查看解析

登录即可查看完整答案

类似问题

Consider the following inheritance hierarchy: If we run the following code, what is printed to the screen?

What is inheritance?

Question at position 8 What concept in object-oriented programming allows creating new classes that reuse code from existing classes?StaticGlobalInheritanceEncapsulationClear my selection

Base classes are also called

When a class inherits another class, it is required to use all the data attributes and methods of the superclass.

A superclass inherits attributes and methods from its subclasses without any of them having to be rewritten.

What does super() do in Python classes?

What does the following code output?

更多留学生实用工具

考试浏览器助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单