Beginner here. This piece of code converts number into roman numerals in multiples of 50 if not 10 if not 9 and down to 0. Methods are so intertwined. Is there something (just at a glance) you could suggest I should avoid doing? Thank You.
public static void main(String[] args) {
System.out.println(fiftyAndAbove(37));
}
public static String nineAndDown(int number) {
String one = "I", five = "V", ten = "X", sum = "";
if(number == 5) {
return five;
} else if(number == 9) {
return one + ten;
}
else if(number > 5) {
for(int i=1; i<=number-5; i++) {
sum += one;
}
return five + sum;
} else {
if(number == 4 ) {
return one + five;
} else
for(int i=1; i <=number; i++) {
sum += one;
}
} return sum;
}
public static String tenAndAbove(int number) {
int remainder = number % 10, numberOftens = number/10;
String ten = "X", sum = "";
if(numberOftens > 0) {
while(numberOftens > 0) {
sum += ten;
numberOftens -= 1;
}
}
return sum + nineAndDown(remainder);
}
public static String fiftyAndAbove(int number) {
int remainder = number % 50, numberOfFifty = number/50;
String fifty = "L", sum = "";
if(numberOfFifty > 0) {
while(numberOfFifty > 0) {
sum += fifty;
numberOfFifty -= 1;
}
}
return sum + tenAndAbove(remainder);
}
Is there something (just at a glance) you could suggest I should avoid doing?
I'd not unnecessarily complicate the logic as with
if(numberOfFifty > 0) {
while(numberOfFifty > 0) {
…
}
}
which is equivalent to
while (numberOfFifty > 0)
{
…
}
You could also have a look at this implementation and see what you prefer:
import java.util.Arrays;
…
public static String fiftyAndAbove(int number)
{
int remainder = number%50, numberOfFifty = number/50;
char [] Ls = new char [numberOfFifty];
Arrays.fill(Ls, 'L');
return new String(Ls) + tenAndAbove(remainder);
}
You have four places like this in your program where you need a string of a character repeated. If you're willing to require a certain Java version or above, you can also use one of the methods described at Java: String - add character n-times; otherwise I'd suggest to use a function to do it.
You could also think about whether you find
String one = "I", five = "V", ten = "X", sum = "";
if(number == 5) {
return five;
} else if(number == 9) {
return one + ten;
}
really better than
if (number == 5) return "V";
if (number == 9) return "IX";
I'm a newbie coder and for a class I was required to make a vending machine-like code. However, I used a switch statement as part of it. An issue I faced is that in those if statements I added a check. The check was to ask if the user would like to continue or not, but for some reason it repeats even after an input. I wasn't entirely sure if this question was asked before, but a lot of my friends share the issue.
import java.util.Scanner;
public class hw52 {
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
String choice;
String answer = "";
int cr = 0;
int wb = 0;
int ch = 0;
int k = 0;
int j = 0;
boolean check = true;
double cost2;
double discount;
double change = 0;
double cost = 0;
double money = 0;
int counter = 0;
do {
answer = "";
System.out.println("Select an option in the vending machine. \n
Crunch:$1.50 \n Water bottle:$2.00 \n Chips:$1.00 \n Ketchup:$4.00 \n
Juice:$2.50");
choice = keyboard.nextLine();
switch(choice.toUpperCase()){
case "CRUNCH":
cost += 1.5;
cr ++;
counter ++;
System.out.println("Cost: " + cost);
while(check = true) {
System.out.println("Do you want to continue? Yes or no?");
answer = keyboard.nextLine();
if (answer.equalsIgnoreCase("Yes")) {
check = false;
}else if(answer.equalsIgnoreCase("Yes")) {
check = false;
}else {
System.out.println("Bad input.");
}
}
case "WATER BOTTLE":
cost += 2.00;
wb++;
counter ++;
System.out.println("Cost: " + cost);
while(check = true) {
System.out.println("Do you want to continue? Yes or no?");
answer = keyboard.nextLine();
if (answer.equalsIgnoreCase("Yes")) {
check = false;
}else if(answer.equalsIgnoreCase("Yes")) {
check = false;
}else {
System.out.println("Bad input.");
}
}
case "CHIPS":
cost += 1.00;
ch++;
counter ++;
System.out.println("Cost: " + cost);
System.out.println("Cost: " + cost);
while(check = true) {
System.out.println("Do you want to continue? Yes or no?");
answer = keyboard.nextLine();
if (answer.equalsIgnoreCase("Yes")) {
check = false;
}else if(answer.equalsIgnoreCase("Yes")) {
check = false;
}else {
System.out.println("Bad input.");
}
}
case "KETCHUP":
cost += 5.00;
k++;
counter ++;
System.out.println("Cost: " + cost);
while(check = true) {
System.out.println("Do you want to continue? Yes or no?");
answer = keyboard.nextLine();
if (answer.equalsIgnoreCase("Yes")) {
check = false;
}else if(answer.equalsIgnoreCase("Yes")) {
check = false;
}else {
System.out.println("Bad input.");
}
}
case "JUICE":
cost += 2.50;
j++;
counter ++;
System.out.println("Cost: " + cost);
while(check = true) {
System.out.println("Do you want to continue? Yes or no?");
answer = keyboard.nextLine();
if (answer.equalsIgnoreCase("Yes")) {
check = false;
}else if(answer.equalsIgnoreCase("Yes")) {
check = false;
}else {
System.out.println("Bad input.");
}
}
default:
System.out.println("Not a choice! Use exact names.");
answer = "yes";
}
}while(!answer.equalsIgnoreCase("no"));
counter /= 3;
for (int i = 0; i < counter;i++) {
discount = (double)(Math.random()*.1)+.1;
cost2 = cost * discount;
cost -= cost2;
}
while(money < cost) {
System.out.println("How much money would you like to use to pay?");
money = keyboard.nextDouble();
if (money < cost) {
System.out.println("That's not enough money.");
}
}
double Q = cost / .25;
double D = (cost % .25) / .10;
double N = ((cost % .25) % .10) / .05 ;
double P = (((cost % .25) % .10) %.05) /.01;
System.out.println("The items you bought are: \n Crunch Bars: " + cr +
"\n Water Bottles: " + wb + "\n Chips: " + ch + "\n Ketchup: " + k + "\n
Juice: " + j);
System.out.println("Your change is: $" + ((Q * .25) + (D * .1) + (N *
.05) + (P*.01)));
}
}
Please excuse my messy coding style. I personally like it better, but I know a lot of people find it strange.
Your code never allows the user to input "no" into the answer variable. So your code always forces the user to intput "yes" or it shows the message "Bad Input".
You have this if statement in each one of your while loops. Both if and else if check the exact same condition. I assume you were probably wanting one of them to check for the answer "no" and the check variable never gets assigned to false unless "yes" is chosen:
answer = keyboard.nextLine();
if (answer.equalsIgnoreCase("Yes")) { //this is same condition as next if line.
check = false;
}else if(answer.equalsIgnoreCase("Yes")) { //this is same condition as prior if line.
check = false;
}else {
System.out.println("Bad input.");
}
Also, this is your main issue. You are ALWAYS assigning check to true in the while loop condition. you want to use the == operator.
This assigns true to the check variable in your code:
while(check = true) {
You actually want to do this:
while(check == true) {
I recommend using an IDE with a debugger that allows you to systematically step through your code and see what is happening with each line of code as it executes. It will help you find logic problems like this one.
I want to normalize a skeleton in order to make it invariant to the size of the person
in front of the kinect; in the same way as the aveteering example.
But I don't want to animate a 3D model using XNA, the only thing I need is to normalize an
skeleton.
So in order to do this task, I have divided it in two functions:
(a) apply a bind pose to an skeleton in order to see how to work this matrix. Obviously this is not what i want to do, but it is a first step in order to
know how to work whit matrix, and so on.
(b) apply any arbitrary pose to a normalized-size-skeleton
First of all, I want to apply a bind pose to an skeleton (a).
First, I have to load the matrix that describe the bone length/ offset between bones and store it in
List BindPose.
Due to I have no idea how to do it, I modified the Aveteering example and write in a file all the Matrix that define
the BindPose, InverseBindPose and SkeletonHierarchy of the dude. I only need BindPose to this first task, but I have the
code prepared in order to do the second task (b)
The file looks like this:
1,331581E-06;-5,551115E-17;1;0;1;-4,16881E-11;-1,331581E-06;0;4,16881E-11;1;8,153579E-23;0;0,03756338;37,46099;2,230549;1
1,110223E-16;-4,435054E-22;1;0;1;1,426127E-06;-2,220446E-16;0;-1,426127E-06;1;-7,654181E-22;0;-0,9558675;-4,079016E-08;-6,266987E-12;1
0,9954988;-0,09477358;1,501821E-06;0;0,09477358;0,9954988;-4,019565E-06;0;-1,114112E-06;4,143805E-06;1;0;3,786007;-0,003599779;5,107028E-06;1
0,9948416;-0,101441;-3,23556E-07;0;0,101441;0,9948416;-2,266755E-08;0;3,241862E-07;-1,027114E-08;1;0;4,543321;-0,00359975;-1,33061E-07;1
0,9950595;0,09927933;2,388133E-07;0;-0,09927933;0,9950595;-2,333792E-08;0;-2,399506E-07;-4,86646E-10;1;0;4,544049;-0,003599948;6,324596E-08;1
0,9992647;0,02747673;0,02674458;0;-0,02928042;0,9971476;0,06956656;0;-0,02475683;-0,07029849;0,9972187;0;4,543965;-0,004398902;2,258555E-07;1
0,9154034;0,4025377;1,107153E-06;0;-0,4025377;0,9154033;-2,437432E-07;0;-1,109319E-06;-2,115673E-07;1;0;5,536249;-0,00288291;1,332601E-07;1
0,9812952;-0,1925096;-4,732622E-07;0;0,1925095;0,9812951;-3,00921E-08;0;4,697166E-07;-5,889972E-08;1;0;3,953898;1,702301E-07;4,88653E-08;1
.......
So each line is a 4X4 matrix defining the BindPose.
To generate this file, the code is like this:
private void ViewSkinningData(SkinningData data)
{
string nameFile = "bind_pose_transformations";
bool append = false;
// The using statement automatically closes the stream and calls IDisposable.Dispose on the stream object.
using (System.IO.StreamWriter file = new System.IO.StreamWriter(#nameFile, append))
{
for (int i = 0; i < data.BindPose.Count; i++)
{
Matrix m = data.BindPose[i];
string matrixString = MatrixToString(m);
file.WriteLine(matrixString);
}
for (int i = 0; i < data.InverseBindPose.Count; i++)
{
Matrix m = data.InverseBindPose[i];
string matrixString = MatrixToString(m);
file.WriteLine(matrixString);
}
for (int i = 0; i < data.SkeletonHierarchy.Count; i++)
{
file.Write(data.SkeletonHierarchy[i] + ";");
}
}
}
string MatrixToString(Matrix m)
{
string result;
result = m.M11 + ";" + m.M12 + ";" + m.M13 + ";" + m.M14 + ";" + m.M21 + ";" + m.M22 + ";" + m.M23 + ";" + m.M24 + ";" + m.M31 + ";" + m.M32 + ";" + m.M33 + ";" + m.M34 + ";" + m.M41 + ";" + m.M42 + ";" + m.M43 + ";" + m.M44;
return result;
}
Next step is to load all this Skinning data in my program:
private void InitializeSkinningDataFromFile()
{
string filename = "bind_pose_transformations";
int number_avatar_joints = 58;
List<Matrix> binpose = new System.Collections.Generic.List<Matrix>();
List<Matrix> inversebindpose = new System.Collections.Generic.List<Matrix>();
List<int> skeletonhierarchy = new System.Collections.Generic.List<int>();
// The using statement automatically closes the stream and calls IDisposable.Dispose on the stream object.
using (System.IO.StreamReader file = new System.IO.StreamReader(filename))
{
string s;
int count = 0;
while (!String.IsNullOrEmpty(s = file.ReadLine()))
{
string[] values = s.Split(';');
Matrix m = BuildMatrix(values);
binpose.Add(m);
count++;
if (count == number_avatar_joints)
{
break;
}
}
count = 0;
while (!String.IsNullOrEmpty(s = file.ReadLine()))
{
string[] values = s.Split(';');
Matrix m = BuildMatrix(values);
inversebindpose.Add(m);
count++;
if (count == number_avatar_joints)
{
break;
}
}
string[] skeletonHierarchy = file.ReadLine().Split(';'); //lee un caracter de separacion al final...
//for (int i = 0; i < skeletonHierarchy.Count(); i++)
for (int i = 0; i < number_avatar_joints; i++)
{
skeletonhierarchy.Add(int.Parse(skeletonHierarchy[i]));
}
}
skinningDataValue = new SkinningData(binpose, inversebindpose, skeletonhierarchy);
}
After, I have to construct boneTransforms structure:
// Bone matrices for the "dude" model
this.boneTransforms = new Matrix[skinningDataValue.BindPose.Count];
this.skinningDataValue.BindPose.CopyTo(this.boneTransforms, 0);
Now boneTransforms have the transformation for my skeleton. So now, i have to apply these trasnformations to an skeleton
Skeleton skeleton = new Skeleton();
foreach (Joint joint in skeleton.Joints)
{
int indexMatrix = AvatarBoneToNuiJointIndex(joint.JointType);
Matrix transform;
if (indexMatrix >= 0)
{
transform = this.boneTransforms[indexMatrix];
}
else
{
transform = Matrix.Identity;
}
Joint aux = ApplyMatrixTransformationToJoint(joint, transform);
normalizeSkel.Joints[joint.JointType] = aux;
}
This is a helper function AvatarBoneToNuiJointIndex:
public int AvatarBoneToNuiJointIndex(JointType jointType)
{
switch (jointType)
{
case JointType.HipCenter:
return 1;
case JointType.Spine:
return 4;
case JointType.ShoulderCenter:
return 6;
case JointType.Head:
return 7;
case JointType.ShoulderLeft:
return 12;
case JointType.ElbowLeft:
return 13;
case JointType.WristLeft:
return 14;
case JointType.HandLeft:
return 15;
case JointType.ShoulderRight:
return 31;
case JointType.ElbowRight:
return 32;
case JointType.WristRight:
return 33;
case JointType.HandRight:
return 34;
case JointType.KneeLeft:
return 50;
case JointType.AnkleLeft:
return 51;
case JointType.FootLeft:
return 52;
case JointType.KneeRight:
return 54;
case JointType.AnkleRight:
return 55;
case JointType.FootRight:
return 56;
default: return -1;
}
}
This is a helper function ApplyMatrixTransformationToJoint:
public Joint ApplyMatrixTransformationToJoint(Joint skeletonJoint, Matrix tranformations)
{
Vector3 pos = SkeletonPointToVector3(skeletonJoint.Position);
Vector3 result = ApplyMatrixTransformationToVector(pos, tranformations);
SkeletonPoint newPosition = new SkeletonPoint()
{
X = result.X,
Y = result.Y,
Z = result.Z
};
skeletonJoint.Position = newPosition;
return skeletonJoint;
}
This is the code for ApplyMatrixTransformationToVector:
static Vector3 ApplyMatrixTransformationToVector(Vector3 v, Matrix m)
{
return Vector3.Transform(v, m);
}
But the problem is that I can't see anything.
I don't know if this approach is correct.
Any help would be fantastic.
Many thanks!
i have a working program where i can add an array to a Zedgraph and show this in a form.
Now i only want to change the display of the x-axis from points (0..400) to frequency (9e3..6e9 Hz).
Here are my currently working functions:
public void AddGraph(double[] Values, string LegendName)
{
int i = 0;
PointPairList list = new PointPairList();
for (i = 0; i < Values.Length; i++)
{
list.Add(i, Values[i]);
}
if (i > MaxXAxis)
MaxXAxis = i;
SList.Add(list);
SListColor.Add(Color.Black);
}
SListName.Add(LegendName);
}
public void ShowDiagram(string Title, string XAxisName, string YAxisName,
int Timeout_ms)
{
ZedGraph.ZedGraphControl zgc = new ZedGraphControl();
GraphPane myPane = zgc.GraphPane;
LineItem myCurve = null;
// Set the titles and axis labels
myPane.Title.Text = Title;
myPane.XAxis.Title.Text = XAxisName;
myPane.YAxis.Title.Text = YAxisName;
for (int i = 0; i < SList.Count(); i++)
{
myCurve = myPane.AddCurve(SListName[i], SList[i], SListColor[i],
SymbolType.None);
myCurve.Line.Width = 2;
}
// Add gridlines to the plot, and make them gray
myPane.XAxis.MinorGrid.IsVisible = true;
myPane.YAxis.MinorGrid.IsVisible = true;
myPane.XAxis.MinorGrid.Color = Color.LightGray;
myPane.YAxis.MinorGrid.Color = Color.LightGray;
myPane.XAxis.MinorGrid.DashOff = 0;
myPane.YAxis.MinorGrid.DashOff = 0;
myPane.XAxis.MajorGrid.IsVisible = true;
myPane.YAxis.MajorGrid.IsVisible = true;
myPane.XAxis.MajorGrid.Color = Color.Gray;
myPane.YAxis.MajorGrid.Color = Color.Gray;
myPane.XAxis.MajorGrid.DashOff = 0;
myPane.YAxis.MajorGrid.DashOff = 0;
// Move Legend to bottom
myPane.Legend.Position = LegendPos.Bottom;
zgc.AxisChange();
myPane.XAxis.Scale.Max = MaxXAxis;
zgc.Location = new Point(0, 0);
zgc.Size = new Size(panel_diagramm.ClientRectangle.Width, panel_diagramm.ClientRectangle.Height);
panel_diagramm.Controls.Add(zgc);
}
How can i change the above two functions that they display the frequency in the x-axis?
I already tried to change the AddGraph-function to pass the needed parameters and to calculate the list to have the correct values. But what then...?
public void AddGraph_Frequency(int **Points**, double **StartFrequency**,
double **StopFrequency**, double[] Values, string GraphColor, string LegendName)
{
...
double frequency = StartFrequency; //der erste Punkt
double Intervall = (StopFrequency - StartFrequency) / Points;
for (i = 0; i < Points; i++)
{
list.Add(frequency, Values[i]);
frequency = frequency + Intervall;
}
....
}
Thanks for any help
best regards
Solved.
Missing was:
myPane.XAxis.Scale.Max = Stopfrequency;
myPane.XAxis.Scale.Min = Startfrequency;
This is a homework, I would appreciate any kind of answer.
Im trying to figure out why i keep getting a NullPointerException when i call the equals method. I have instantiated the object if im not mistaken, but it still doesn't work.
Exception in thread "main" 8
java.lang.NullPointerException
at labbfyra.TextBuilder.equals(TextBuilder.java:69)
at labbfyra.SkapaOrd.main(SkapaOrd.java:17)
Is this the stacktrace?
public class TextBuilder {
private static class Node{
public char inChar;
public Node next;
public Node(char c, Node nästa){
inChar = c;
next = nästa;
}
}
private Node first = null;
private Node last = null;
public TextBuilder(){
first = null;
last = null;
}
public void append(String s){
int x = s.length();
for(int i=0;i<x;i++){
Node n = new Node(s.charAt(i),null);
if(first ==null){
first = n;
last = n;
}else{
last.next = n;
last = n;
}
}
}
public int ShowSize(){
int counter = 0;
Node n = first;
while(n!=null){
counter++;
n=n.next;
}
return counter;
}
public boolean equals(String s){
boolean eq = false;
int counter = 0;
char[] cArray = s.toCharArray();
char[] cArrayComp = new char[10];
Node n = first;
cArrayComp[counter] = n.inChar;
while(n!=null){
counter++;
n=n.next;
cArrayComp[counter] = n.inChar; //THIS IS LINE 69
}
if(cArrayComp==cArray){
eq = true;
}
else{
eq=false;
}
return eq;
}
}
In your while loop, you check that n is not null, but then you assign n.next to n just before accessing n. The problem is that you do not ensure that the assigned value (n.next) is not null.
At a quick glance, looks like the counter variable in your while loop is going past the 10 you set your cArrayComp size to. Perhaps the string parameter being passed is longer than 10 chars?
public boolean equals(String s){
boolean eq = false;
int counter = 0;
char[] cArray = s.toCharArray();
char[] cArrayComp = new char[10];
Node n = first;
while(n!=null){
System.out.println(counter);
cArrayComp[counter] = n.inChar;
System.out.println(cArrayComp[counter]);
System.out.println(n.inChar);
n=n.next;
counter++;
}
if(cArrayComp==cArray){
eq = true;
}
else{
eq=false;
}
return eq;
}
This is the corrected version, i found a bug in your loop. Just check my version. Works at 100%