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代写CS 284留学生作业、代做java课程设计作业、java程序语言作业调试、代做binary number作业
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CS 284: Homework Assignment 1

Due: September 7, 11:55pm

1 Assignment Policies

Collaboration Policy. Homework will be done individually: each student must hand in

their own answers. It is acceptable for students to collaborate in understanding the material

but not in solving the problems or programming. Use of the Internet is allowed, but should

not include searching for existing solutions.

Under absolutely no circumstances code can be exchanged between students.

Excerpts of code presented in class can be used.

Your code must include a comment with your name and section .

2 Assignment

Define a class BinaryNumber that represents binary numbers and a few simple operations on

them, as indicated below. An example of a binary number is

1011

Its length is 4. Note that its leftmost digit is the most significant one: it represents the

decimal number 1 ∗ 2

3 + 0 ∗ 2

2 + 1 ∗ 2

1 + 1 ∗ 2

0 = 11. This is called big-endian format. Please

be sure to use big-endian format in your program.

This assignment requests that a number of operations be supported. They are divided

into two groups. The first is a set of basic operations, the second is slightly more challenging

and addresses addition of binary numbers.

2.1 Basic operations

The following operations should be supported:

• A constructor BinaryNumber(int length) for creating a binary number of length length

and consisting only of zeros.

• A constructor BinaryNumber(String str) for creating a binary number given a string. For

example, given the string "1011", the corresponding binary number should be created.

For this exercise you will have to use some standard String operations. These are listed

in the “Hints” section below.

1

• An operation int getLength() for determining the length of a binary number.

• An operation int[] getInnerArray() that returns the integer array representing the binary

number.

• An operation int getDigit(int index) for obtaining a digit of a binary number given an

index. The starting index is 0. If the index is out of bounds, then a message should

be printed on the screen indicating this fact.

• An operation int toDecimal() for transforming a binary number to its decimal notation

(cf. the example given above).

• An operation void bitShift(int direction, int amount) for shifting all digits in a binary

number any number of places to the left or right. The direction parameter indicates

a left shift when the value is -1. When direction is given the value 1, the shift should

be to the right. Any other value for direction should be seen as invalid. The amount

parameter specifies how many digits the BinaryNumber will be shifted, and is only

valid when it is nonnegative. For example, ’1011’ shifted right by 2 is ’10’. ’1011’

shifted left by 2 is ’101100’. Notice that shifting right decreases the number by

factors of 2, while shifting left increases the number by factors of 2. These operations

are equivalent to the ”>>” and ”<<” operators in Java.

• An operation static int[] bwor(BinaryNumber bn1, BinaryNumber bn2) that computes the

bitwise or of the two numbers. Note that both argument BinaryNumbers must be of

the same length for the input to be considered valid. The bitwise or of ’1010’ and

’1100’ is ’1110’.

• An operation static int[] bwand(BinaryNumber bn1, BinaryNumber bn2) that computes the

bitwise and of the two numbers. Note that both argument BinaryNumbers must be of

the same length for the input to be considered valid. The bitwise and of ’1010’ and

’1100’ is ’1000’.

• An operation String toString() that returns the BinaryNumber as the corresponding

encoded string.

2.2 Addition of Binary Numbers

Here is an example of how two binary numbers of the same length are added1

.

1 1 (carried digits)

0 1 1 0 1

+ 0 1 0 0 1

= 1 0 1 1 0 = 22

Note that it is possible for the addition of two numbers to yield a result which has a

larger length than the summands. In that case, room should be made for the extra digit -

meaning the array should be copied over to a new one that is one greater in length.

1Source: https://en.wikipedia.org/wiki/Binary_number

2

1 1 1 (carried digits)

1 0 1 1 0

+ 1 1 1 0 1

= 1 1 0 0 1 1 = 51

The int[] field data should be added to the data fields of BinaryNumber.

Implement the following operations:

• void add(BinaryNumber aBinaryNumber) for adding two binary numbers, one is the binary

number that receives the message and the other is given as a parameter. If the lengths

of the two BinaryNumbers do not coincide, then the smaller one should have 0’s

prepended to it in order to prevent errors. Note how ’101’ + ’1’ is the same as ’101’

+ ’001’. The BinaryNumber which receives aBinaryNumber should be modified with

the result of addition.

2.3 Hints

• For the BinaryNumber(String str) constructor, the following operations might come in

handy:

– char java.lang.String.charAt(int index), which returns the char value at the specified

index. An index ranges from 0 to length() - 1. The first char value of the

sequence is at index 0, the next at index 1, and so on, as for array indexing.

– int java.lang.Character.getNumericValue(char ch), which returns the int value that

the specified Unicode character represents.

• For methods where allocating more space is necessary, it may be useful to define a

static void prepend(int amount) method, that preprends amount 0’s to the BinaryNumber.

3 Submission instructions

Submit a single file named BinaryNumber.java through Canvas. No report is required.

Your grade will be determined as follows:

• You will get 0 if your code does not compile.

• The code must implement the following UML diagram precisely (see below).

• We will try to feed erroneous and inconsistent inputs to all methods. All arguments

should be checked.

• Partial credit may be given for style, comments and readability.

3

BinaryNumber

private int data[]

private int length

public BinaryNumber(int length)

public BinaryNumber(String str)

public int getLength()

public int getDigit(int index)

public int[] getInnerArray()

public static int[] bwor(BinaryNumber bn1, BinaryNumber bn2)

public static int[] bwand(BinaryNumber bn1, BinaryNumber bn2)

public void bitShift(int direction, int amount)

public void add(BinaryNumber aBinaryNumber)

public String toString()

public int toDecimal()

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