Question

What is wrong with this Code? Fix the code errors to run correctly without error. There are two parts for one code (one question) the two parts branch off, one part has 2 sheets of code, the other has 3 sheets of code, all are small code segments for one question.

Pt.1 - 2 sheets of code:

public class Computer {

private String make; private String type; private String modelNumber;
private double cpuSpeed_GHz; private int ramSize_GB;
private int hardDriveSize_GB; private double price;

public Computer(String make, String type, String modelNumber,
double cpuSpeed_GHz, int ramSize_GB,
int hardDriveSize_GB, double price){

make = make;
type = type;
modelNumber = modelNumber;
cpuSpeed_GHz = cpuSpeed_GHz;
ramSize_GB = ramSize_GB;
hardDriveSize_GB = hardDriveSize_GB;
price = price;
}

public double getCpuSpeed_GHz() {
return cpuSpeed_GHz;
}

public int getHardDriveSize_GB() {
return hardDriveSize_GB;
}

public String getMake() {
return make;
}

public String getModelNumber() {
return modelNumber;
}

public double getPrice() {
return price;
}

public int getRamSize_GB() {
return ramSize_GB;
}

public String getType() {
return type;
}

public void setCpuSpeed_Ghz(double cpuSpeed_GHz) {
this.cpuSpeed_GHz = cpuSpeed_GHz;
}

public void setHardDriveSize_GB(int hardDriveSize_GB) {
this.hardDriveSize_GB = hardDriveSize_GB;
}

public void setMake(String make) {
this.make = make;
}

public void setModelNumber(String modelNumber) {
this.modelNumber = modelNumber;
}

public void setPrice(double price) {
this.price = price;
}

public void setRamSize_GB(int ramSize_GB) {
this.ramSize_GB = ramSize_GB;
}

public void setType(String type) {
this.type = type;
}
}

public class ComputerTest {
public static void main(String[] args){
Computer computer = new Computer("Dell", "Laptop", "Inspiron 17R",
2.3, 4, 500, 1200.50);
  
System.out.printf("%s", computer.getMake());
System.out.printf(" %s", computer.getType());
System.out.printf(" %s\n", computer.getModelNumber());
System.out.printf("%.2f GHz CPU,", computer.getCpuSpeed_GHz());
System.out.printf(" %d GB Memory\n", computer.getRamSize_GB());
System.out.printf("%d GB Hard Drive\n", computer.getHardDriveSize_GB());
System.out.printf("Cost $%,.2f\n", computer.getPrice());
}
}

Pt.2 - 3 sheets of code

public class BigScientificMathProgram {
public void generateSomeBigScientificCalcuation(){
System.out.printf("The speed of light is [m/s]: %,d\n",
ScienceMathConstants.SPEED_OF_LIGHT_METERS_PER_SECONDS);
System.out.printf("The speed of sound is [km/hr]: %,d\n",
ScienceMathConstants.SPEED_OF_SOUND_KILOMETERS_PER_HOUR);
System.out.printf("The distance from the earth to the sun is [kilo]: %,d\n",
ScienceMathConstants.DISTANCE_FROM_EARTH_TO_SUN_KILOMETERS);
}
}

public class BigScientificMathProgramTest {
public static void main(String[] args) {
BigScientificMathProgram bsmp = new BigScientificMathProgram();
bsmp.generateSomeBigScientificCalcuation();
}
}

public class ScienceMathConstants {
public int SPEED_OF_LIGHT_METERS_PER_SECONDS = 299792458; // meters per second
public int SPEED_OF_SOUND_KILOMETERS_PER_HOUR = 1236; // kilometres per hour
public int DISTANCE_FROM_EARTH_TO_SUN_KILOMETERS = 150000000; // kilometers
}

Answer 1

Part 1: BigScientificMathProgram

In this part, there is an error in class ScienceMathConstants. In this, we are using class variables in the main method which is a static method and we can't access not static objects from static methods.

To fix this, we need to make all variables in ScienceMathConstants as static.

Below is the complete code of Part 1 where the updated code has been highlighted in bold.

public class ScienceMathConstants {

    // static variables
    public static int SPEED_OF_LIGHT_METERS_PER_SECONDS = 299792458; // meters per second
    public static int SPEED_OF_SOUND_KILOMETERS_PER_HOUR = 1236; // kilometres per hour
    public static int DISTANCE_FROM_EARTH_TO_SUN_KILOMETERS = 150000000; // kilometers
}

public class BigScientificMathProgram {

    public void generateSomeBigScientificCalcuation() {
        System.out.printf("The speed of light is [m/s]: %,d\n",
                ScienceMathConstants.SPEED_OF_LIGHT_METERS_PER_SECONDS);
        System.out.printf("The speed of sound is [km/hr]: %,d\n",
                ScienceMathConstants.SPEED_OF_SOUND_KILOMETERS_PER_HOUR);
        System.out.printf("The distance from the earth to the sun is [kilo]: %,d\n",
                ScienceMathConstants.DISTANCE_FROM_EARTH_TO_SUN_KILOMETERS);
    }
}

public class BigScientificMathProgramTest {

    public static void main(String[] args) {
        BigScientificMathProgram bsmp = new BigScientificMathProgram();
        bsmp.generateSomeBigScientificCalcuation();
    }
}

Below is the sample output:

run: The speed of light is [m/s] 299,792 , 458 The speed of sound is [km/hr]: 1,236 The distance from the earth to the sun is [kilol 150, 000, 000

Part 2 - Computer

This is not generating the correct output for computer details. This is happening because in constructor of Computer class, we are assigning the value of variables to itself. To fix this, we need to make it to refer object variables using this keyword.

Below is the complete code of Part 2 where the updated code has been highlighted in bold.

public class Computer {

    private String make;
    private String type;
    private String modelNumber;
    private double cpuSpeed_GHz;
    private int ramSize_GB;
    private int hardDriveSize_GB;
    private double price;

    public Computer(String make, String type, String modelNumber,
            double cpuSpeed_GHz, int ramSize_GB,
            int hardDriveSize_GB, double price) {

        this.make = make;
        this.type = type;
        this.modelNumber = modelNumber;
        this.cpuSpeed_GHz = cpuSpeed_GHz;
        this.ramSize_GB = ramSize_GB;
        this.hardDriveSize_GB = hardDriveSize_GB;
        this.price = price;
    }

    public double getCpuSpeed_GHz() {
        return cpuSpeed_GHz;
    }

    public int getHardDriveSize_GB() {
        return hardDriveSize_GB;
    }

    public String getMake() {
        return make;
    }

    public String getModelNumber() {
        return modelNumber;
    }

    public double getPrice() {
        return price;
    }

    public int getRamSize_GB() {
        return ramSize_GB;
    }

    public String getType() {
        return type;
    }

    public void setCpuSpeed_Ghz(double cpuSpeed_GHz) {
        this.cpuSpeed_GHz = cpuSpeed_GHz;
    }

    public void setHardDriveSize_GB(int hardDriveSize_GB) {
        this.hardDriveSize_GB = hardDriveSize_GB;
    }

    public void setMake(String make) {
        this.make = make;
    }

    public void setModelNumber(String modelNumber) {
        this.modelNumber = modelNumber;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public void setRamSize_GB(int ramSize_GB) {
        this.ramSize_GB = ramSize_GB;
    }

    public void setType(String type) {
        this.type = type;
    }
}

Below is the output after fixing the code:

run: Dell Laptop Inspiron 17R 2.30 GHz CpU, 4 GB Memory 500 GB Hard Drive Cost $1,200.50

This completes the requirement. Let me know if you have any queries.

Thanks!