Question

The question is as follows with all of the requirements commented in.

/**

* A class that represents a Hounsfield unit. Hounsfield units are the units of

* measurement used in computed tomography (CT or CAT) scanning.

*

* <p>

* The Hounsfield scale is defined by specifying the radiodensity of air as

* {@code -1000} Hounsfield units and the radiodensity of distilled water as

* {@code 0} Hounsfield units. Adjacent tissues in the human body can be

* distinguished from one another if their radiodensities differ; see

* <a href="https://en.wikipedia.org/wiki/Hounsfield_scale">the Wikipedia

* page</a> for a table of typical Hounsfield values for tissues of the

* human body.

*

* <p>

* CT scanners for medical purposes typically restrict the value of reported

* Hounsfield units to integers in the range {@code -1024} to {@code 3071} so

* that a Hounsfield unit can be encoded as a 12-bit value. This class uses

* the values {@code -1024} and {@code 3071} to represent the minimum and

* maximum, respectively, allowable Hounsfield unit values.

*

*/

public class Hounsfield {

/**

* The integer value of this Hounsfield unit

*/

private int value;

/**

* The minimum Hounsfield unit reported by medical CT scanners

* Look up the correct value in the documentation

*/

public static final int MIN_VALUE = 0;

/**

* The maximum Hounsfield unit reported by medical CT scanners

* Look up the correct value in the documentation

*/

public static final int MAX_VALUE = 0;

/**

* Initializes this Hounsfield unit to have a value of zero.

*/

public Hounsfield() {

// A constructor should assign every non-static field a value.

// Change the next line to assign the correct value to this.value

// or use constructor chaining.

//

// Implement the get method before trying to run the JUnit test.

// If you used constructor chaining you will also have to implement

// the next constructor before running the JUnit test.

this.value = -1000;

}

/**

* Initializes this Hounsfield unit to have the specified value.

*

* @param value

* the value of this Hounsfield unit

* @throws IllegalArgumentException

* if {@code value} is less than the minimum Hounsfield unit

* reported by medical CT scanners or greater than the maximum

* Hounsfield unit reported by medical CT scanners

*/

public Hounsfield(int value) {

// If you implement the set method first, you can simply call set

// from within this constructor to implement the constructor.

//

// Alternatively, implement the checkValue method first and call

// it from within this constructor to perform the necessary

// input validation, and then assign the appropriate value to this.value

}

/**

* Initializes this Hounsfield unit by copying the value from the specified

* other Hounsfield unit.

*

* @param other

* the Hounsfield unit to copy the value from

*/

public Hounsfield(Hounsfield other) {

// Assign a value to this.value by copying other.value

}

/**

* Throws an {@code IllegalArgumentException} if the specified value is less

* than the minimum Hounsfield unit reported by medical CT scanners or

* greater than the maximum Hounsfield unit reported by medical CT scanners.

*

* @param value

* a value to check

* @throws IllegalArgumentException

* if the specified value is less than the minimum Hounsfield

* unit reported by medical CT scanners or greater than the

* maximum Hounsfield unit reported by medical CT scanners.

*/

private static void checkValue(int value) {

// This method is useful for implementing the input validation

// needed in the constructor and in the method set

}

/**

* Returns the value of this Hounsfield unit.

*

* @return the value of this Hounsfield unit

*/

public int get() {

// Change the next line to return the value of this.value

return -1;

}

/**

* Sets the value of this Hounsfield unit to the specified value returning

* the value that was overwritten.

*

* @param value

* the value to set this Hounsfield unit to

* @return the overwritten value of this Hounsfield unit

* @throws IllegalArgumentException

* if the specified value is less than the minimum Hounsfield

* unit reported by medical CT scanners or greater than the

* maximum Hounsfield unit reported by medical CT scanners.

*/

public int set(int value) {

// Call checkValue on the first line to perform input validation

return 0;

}

/**

* Returns a string representation of this Hounsfield unit. The returned

* string is the numeric value of this Hounsfield unit (formatted as an

* integer) followed by a space followed by the string {@code "HU"}.

*/

@Override

public String toString() {

// Change the next line to return the approriate string

return "";

}

}

Answer 1

Hounsfield.java

public class Hounsfield {
private int value;
private static final int MIN_VALUE = -1024;
private static final int MAX_VALUE = 3071;
  
public Hounsfield()
{
this.value = 0;
}
  
public Hounsfield(int value)
{
checkValue(value);
this.value = value;
}
  
public Hounsfield(Hounsfield other)
{
checkValue(other.get());
this.value = other.get();
}
  
private void checkValue(int value)
{
if(value < MIN_VALUE || value > MAX_VALUE)
throw new IllegalArgumentException(this.getClass().getSimpleName() + "Value should be between " + MIN_VALUE + " and " + MAX_VALUE);
}
  
public int get()
{
return this.value;
}
  
public int set(int value)
{
int previous = this.value;
checkValue(value);
this.value = value;
return previous;
}
  
@Override
public String toString()
{
return (this.value + " HU");
}
}

HounsfieldTester.java (Driver class)

public class HounsfieldTester {
  
public static void main(String[] args)
{
try
{
// using 1st constructor
Hounsfield hf1 = new Hounsfield();
hf1.set(590);

// using 2nd constructor
Hounsfield hf2 = new Hounsfield(3000);

//using 3rd constructor
Hounsfield hf3 = new Hounsfield(hf1);
  
// displaying all the 3 objects using their respective toString() methods
System.out.println("Object 1: " + hf1.toString());
System.out.println("Object 2: " + hf2.toString());
System.out.println("Object 3: " + hf3.toString());
  
}catch(IllegalArgumentException iae){
System.out.println(iae.getMessage());
}
}
}

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