4.1 Bit Manipulation and the Bitwise Operators

Table: The bitwise operators

&	bitwise AND
|	bitwise inclusive OR
^	bitwise exclusive OR
<<	left shift
>>	right shift with sign extension
>>>	right shift with zero extension
~	one's complement

In this exercise, you'll be guided through manipulating an integer as a bit string, and in how to extract arbitrary fields from the string. Finally, we'll cover how to convert arbitrary length bit strings in signed numerical values.

1. Complete the following application that takes a 32 bit signed integer and prints it out as a bit string. Your task is to complete the toString method to print out in a binary representation. Obtain the integer value from arguments to the program.

   class BitString {
     private int value;    // The 32 bit value of this bitstring
   
     public BitString(int value) {
       this.value = value;
     }
   
     public int getValue() {
       return(this.value);
     }
   
     public void setValue(int toValue) {
       this.value = toValue;
     }
   
     public String toString() {}
   
     public static void main(String args[]) {
        int testValue = 15;
        if(args.length > 0) {
           testValue = Integer.parseInt(args[0]);
        } // Could extend this to get args[1] or args[2] for further input
        // Do something with testValue
     }
   }
   

2. Now extend the class to ask the user for a start point and a width of field to print out. Print the binary representation of those fields.
3. Finally modify the code to print out both the signed and unsigned values of the extracted fields as decimal numbers.