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Why does it display the value "null" if the conditions of the method are met?

I'm trying to compile my first major program. Unfortunately in getBestFare() I get "null" coming out all the time. And it shouldn't! I'm asking you guys for help what's wrong.
I rebuilt the entire getBestFare() method but unfortunately it keeps coming up with "null". The earlier code was a bit more messy. Now it's better, but it still doesn't work.
public class TransitCalculator {
public int numberOfDays;
public int transCount;
public TransitCalculator(int numberOfDays, int transCount) {
if(numberOfDays <= 30 && numberOfDays > 0 && transCount > 0){
this.numberOfDays = numberOfDays;
this.transCount = transCount;
} else {
System.out.println("Invalid data.");
}
}
String[] length = {"Pay-per-ride", "7-day", "30-day"};
double[] cost = {2.75, 33.00, 127.00};
public double unlimited7Price(){
int weekCount = numberOfDays/7;
if (numberOfDays%7>0){
weekCount+=1;
}
double weeksCost = weekCount * cost[1];
return weeksCost;
}
public double[] getRidePrices(){
double price1 = cost[0];
double price2 = ((cost[1]*unlimited7Price()) / (unlimited7Price() * 7));
double price3 = cost[2] / numberOfDays;
double[] getRide = {price1, price2, price3};
return getRide;
}
public String getBestFare(){
int num = 0;
for (int i = 0; i < getRidePrices().length; i++) {
if(getRidePrices()[i] < getRidePrices()[num]){
return "You should get the " + length[num] + " Unlimited option at " + getRidePrices()[num]/transCount + " per ride.";
}
}
return null;
}
public static void main(String[] args){
TransitCalculator one = new TransitCalculator(30, 30);
System.out.println(one.unlimited7Price());
System.out.println(one.getRidePrices()[2]);
System.out.println(one.getBestFare());
}
}

Sum Jtable coumn values in java

guys, my question is about jtable column values, I am stuck on a problem. I want to sum jtable column values and put it into the text field. I am inserting values into jtable and if a row is empty, it is not calculating the total afterward. I couldn't understand what is the problem. I created a method and call it on button event.
public void getSum(){
int total=0;
for(int i=0; i<JV_tbl.getRowCount(); i++){
int amount = Integer.parseInt((String) JV_tbl.getValueAt(i, 6));
total+=amount;
}
JV_totalDebit_box.setText(String.valueOf(total));
}
and the button event code.
private void btn_entrySaveActionPerformed(java.awt.event.ActionEvent evt) {
model = (DefaultTableModel)JV_tbl.getModel();
model.addRow(new Object[]{
jv_no_box.getText(),
JV_entry_box.getText(),
((JTextField)date_txt.getDateEditor().getUiComponent()).getText(),
JV_Acc_code.getText(),
JV_acc_title.getText(),
JV_desc_box.getText(),
JV_debit_box.getText(),
JV_credit_box.getText(),
prep_box.getText(),
checked_box.getText(),
approved_box.getText()
});
getSum();
}

Change your getSum() function as below. It will remove all the blank rows and will continue the total afterward.
public void getSum(){
int rowcount1 = JV_tbl.getRowCount();
DefaultTableModel tbm1 = (DefaultTableModel) JV_tbl.getModel();
for(int i = rowcount1-1; i >=0; i--){
if(JV_tbl.getValueAt(i, 6) == null){
tbm1.removeRow(i);
}
}
int total=0;
for(int i=0; i<JV_tbl.getRowCount(); i++){
int amount = Integer.parseInt(JV_tbl.getValueAt(i, 6).toString());
total+=amount;
}
JV_totalDebit_box.setText(String.valueOf(total));
}

JTable object [][] data

I am trying to create a table based on my trial class. When I try to run my table class the table prints with the proper heading, but it does not print anything in the body of the table. How should I fix my for loop so the data enters the table? Do I need to add a parameter to the constructor?
I understand there are more getters and setters than necessary. I was just trying to go about the for loop in different ways.
public class Trial extends JFrame{
static int counter = 0;
int laps = 0;
String lapTime;
double currentTime = 0;
String difference;
int lapsCount = 0;
String[] array1;
double[] array2;
double[] array3;
public int getLapsCount() {
return lapsCount;
}
public void setLapsCount(int lapsCount) {
this.lapsCount = lapsCount;
}
public static int getCounter() {
return counter;
}
public static void setCounter(int counter) {
Trial.counter = counter;
}
public int getLaps() {
return laps;
}
public void setLaps(int laps) {
this.laps = laps;
}
public String getLapTime() {
return lapTime;
}
public void setLapTime(String lapTime) {
this.lapTime = lapTime;
}
public double getCurrentTime() {
return currentTime;
}
public void setCurrentTime(double currentTime) {
this.currentTime = currentTime;
}
public String getDifference() {
return difference;
}
public void setDifference(String difference) {
this.difference = difference;
}
public String[] getArray1() {
return array1;
}
public void setArray1(String[] array1) {
this.array1 = array1;
}
public double[] getArray2() {
return array2;
}
public void setArray2(double[] array2) {
this.array2 = array2;
}
public double[] getArray3() {
return array3;
}
public void setArray3(double[] array3) {
this.array3 = array3;
}
public static void main(String[] args) {
//drop down for number of laps
String lapsString;
String[] selections = { "1", "2", "3", "4", "5", "6", "7", "8", "9", "10"};
lapsString = (String) JOptionPane.showInputDialog(null,
"Choose a number of laps:",
"Lap Counter",
JOptionPane.INFORMATION_MESSAGE,
null, /* icon */
selections,
"0");
System.out.printf("Number of laps = \"%s\"\n", lapsString);
int lapsCount = Integer.parseInt(lapsString);
String[] array1 = new String[lapsCount+1];
double[] array2 = new double[lapsCount+1];
double[] array3 = new double[lapsCount+1];
// showInputDialog with for lap time
for (int i = 1; i <= lapsCount; i++){
String lapTime;
lapTime =
JOptionPane.showInputDialog("Enter lap " + i + " total time.");
System.out.printf("Lap " + i + " = \"%s\"\n", lapTime);
array1[i] = lapTime;
double currentTime = inputConvert(array1[i]);
array2[i] = currentTime;
array3[i] = (array2[i] - array2[i-1]);
counter++;
//confirm each time
int result;
String[] results = { "Yes", "No", "Cancel" };
result = JOptionPane.showConfirmDialog(null,
"Please confirm lap " + i + " is " + lapTime);
if (result == -1)
System.out.printf("user closed window\n");
else if (result == 0)
System.out.printf("result = %d, user pressed \"%s\"\n", result, results[result]);
else {
lapTime =
JOptionPane.showInputDialog("Please re-enter lap " + i);
System.out.printf("Lap " + i + " = \"%s\"\n", lapTime);
counter++;
}
}
}
public static double inputConvert(String s) {
double convert = 0.0;
int minutes = Integer.parseInt(s.substring(0, 1));
double seconds = Double.parseDouble(s.substring(2, s.length()));
minutes = minutes * 60;
convert = minutes + seconds;
return convert;
}
private static String getDifference(int j, double sign) {
String difference = "";
if(j == 0) {
difference = "---";
}
else if(sign > 0.0) {
difference = "+";
}
return difference;
}
public static String displayTime(double time) {
String result = null;
int minutes = (int) (time/60);
double seconds = (time % 60);
seconds = Math.round(seconds*100.0)/100.0;
if(seconds < 10){
result = minutes + ":0" + seconds;
}
else{
result = minutes + ":" + seconds;
}
return result;
}
}
This is my table class where the problem arises.
public class table {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new table();
}
});
}
public table() {
JFrame guiFrame = new JFrame();
guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
guiFrame.setTitle("Table to record lap times");
guiFrame.setSize(700,200);
guiFrame.setLocationRelativeTo(null);
JTable table = new JTable(new ExampleTableModel());
table.setAutoCreateRowSorter(true);
table.setGridColor(Color.YELLOW);
table.setBackground(Color.CYAN);
JScrollPane tableScrollPane = new JScrollPane(table);
guiFrame.add(tableScrollPane);
guiFrame.setVisible(true);
}
class ExampleTableModel extends AbstractTableModel{
int laps = 0;
String lapTime;
double currentTime = 0;
String difference;
Trial t = new Trial();
//Two arrays used for the table data
private String[] columnNames = {"Lap #", "Total Time", "Lap Time" , "Difference" };
private Object[][] data;
public ExampleTableModel(){
data = new Object[laps][4];
for(int i = 0; i < laps; i++){
data[i][0] = "Lap " + i;
data[i][1] = t.getArray1() [i];
data[i][2] = t.getArray2()[i];
data[i][3] = t.getArray3()[i];
}
}
#Override public int getRowCount() {
return data.length;
}
#Override public int getColumnCount() {
return columnNames.length;
}
#Override public Object getValueAt(int row, int column) {
return data[row][column];
}
#Override public String getColumnName(int column) {
return columnNames[column];
}
#Override public Class getColumnClass(int c) {
return getValueAt(0, c).getClass();
}
#Override public boolean isCellEditable(int row, int column) {
if (column == 0 || column == 1) {
return false;
}
else {
return true;
}
}
}
}
I made those changes but I need my output to look like this
Lap #: Total time Lap time Difference
Lap1: 2:10 2:10 ---
I fixed the lap number so it starts at 1. I made these changes in the hopes that it would fix the lap time and difference cells but it is giving me an error.
public ExampleTableModel(Trial trial){
int laps = trial.getLapsCount();
data = new Object[laps][4];
for(int i = 0; i < laps; i++){
if (i == 0){
data[i][0] = "Lap " + (i + 1);
data[i][1] = trial.getArray1() [i + 1];
data[i][2] = trial.getArray2() [i + 1];
data[i][3] = trial.getDifference(i, (trial.getArray3()[i + 1] - trial.getArray3()[i]));
}
else {
data[i][0] = "Lap " + (i + 1);
data[i][1] = trial.getArray1() [i + 1];
data[i][2] = trial.displayTime(trial.getArray2() [i + 1] - trial.getArray2() [i]);
data[i][3] = trial.getDifference(i, (trial.getArray3()[i + 1] - trial.getArray3()[i])) + (trial.getArray3()[i + 1] - trial.getArray3()[i]);
}
}
}

Edit: combining the code from the Trial.main and the Table.main methods
To make the code from your Trial class easier to use from the Table class, you can make the following changes. This way you can create a Trial object and call the getUserInput to let the user initialize it:
public static void main(String[] args) {
new Trial().getUserInput();
}
public void getUserInput() {
// [Code from the old main method...]
// Use the fields of the class instead of local variables:
lapsCount = Integer.parseInt(lapsString);
array1 = new String[lapsCount+1];
array2 = new double[lapsCount+1];
array3 = new double[lapsCount+1];
// [Code from the old main method...]
}
Now you can modify the Table model like this:
public Table() {
// [...]
Trial trial = new Trial();
trial.getUserInput();
JTable table = new JTable(new ExampleTableModel(trial));
// [...]
}
And let the ExampleTableModel constructor use a trail parameter (the laps and t fields are no longer used):
public ExampleTableModel(Trial trial){
int laps = trial.getLapsCount();
data = new Object[laps][4];
for(int i = 0; i < laps; i++){
data[i][0] = "Lap " + i;
data[i][1] = trial.getArray1()[i];
data[i][2] = trial.getArray2()[i];
data[i][3] = trial.getArray3()[i];
}
}
There was also an issue with the getColumnClass method:
#Override public Class getColumnClass(int column) {
//return getValueAt(0, column).getClass();
return (column <= 1) ? String.class : Double.class;
}
Now the table looks like this:
The output was:
Number of laps = "2"
Lap 1 = "2:10"
result = 0, user pressed "Yes"
Lap 2 = "2:20"
result = 0, user pressed "Yes"
Old answer
There seem to be a few issues that prevent the table from being filled:
In the ExampleTableModel class the laps field should be something higher than zero (for the constructor to fill the data array):
class ExampleTableModel extends AbstractTableModel {
//int laps = 0;
int laps = 6;
In the constructor of the ExampleTableModel class:
public ExampleTableModel(){
data = new Object[laps][4];
for(int i = 0; i < laps; i++){
data[i][0] = "Lap " + i;
data[i][1] = t.getArray1()[i];
data[i][2] = t.getArray2()[i];
data[i][3] = t.getArray3()[i];
}
}
the calls to the t.getArray1, t.getArray2, and t.getArray3 methods return null. The Trial object appears to have no data yet.
Do you want your program to execute both the code of the Trial.main method and the Table.main method?

Methods to display different table content, repeating header issue

I need to be able to use different methods in order to print out certain table content such as a sum, multiplication, or random table to name a few. I cannot figure out how to print out this content separate from the row ID. another problem I am having is when I enter "f" to reprint the table the header gets repeated each time I print it which just creates a very long repeating header after a few reprints, could someone help with this?
The original code will be followed by the IntTable class, it is not completely filled out which I am aware of but I want to figure this out before I move on.
import java.util.Scanner;
public class Assignment6{
public static String returnMenu(){
String menu = "Command Options---------------\na: Create a new table\nb: Change the row sizes\nc: Change the column sizes\nd: Change the data types\ne: Chnge the formats\nf: Display the table\ng: Display the log data\n:?: Display this menu\nq: Quit the program\n------------------------------";
return menu;
}
public static void main(String[] arg){
Scanner scan = new Scanner(System.in);
String input = "p";
String output = "NOOOOO!";
IntTable myTable = new IntTable();
while (!input.equals("q")){
System.out.println("Please input a command: ");
input = scan.nextLine();
if (input.equals("a")){
System.out.print("a [Input three integers to initialize table]: ");
myTable.setRow(scan.nextInt()); myTable.setColumn(scan.nextInt()); myTable.setType(scan.nextInt());
scan.nextLine();
myTable.printTable();
}
else if (input.equals("b")){
System.out.print("b [Enter integer to update table row]: ");
myTable.setRow(scan.nextInt());
scan.nextLine();
}
else if (input.equals("c")){
System.out.println("c [Enter integer to update column]: ");
myTable.setColumn(scan.nextInt());
scan.nextLine();
}
else if (input.equals("d")){
System.out.println("d [Enter integer to update data type]: ");
myTable.setType(scan.nextInt());
scan.nextLine();
}
else if (input.equals("e")){
System.out.println("e [Enter integer to update printf format]: ");
}
else if (input.equals("f")){
System.out.println("f [Display table]: ");
myTable.printTable();
}
else if (input.equals("g")){
System.out.println("g [Display data log]: ");
}
else if (input.equals("?")){
System.out.println(Assignment6.returnMenu());
}
else
System.out.println("Invalid: ***Type \"?\" to get the commands***");
}
}
}
public class IntTable{
private int row, column, type;
static String log, tFormat;
final int TYPE_DEFAULT = 0;
final int TYPE_NUMBERS = 1;
final int TYPE_SUM = 2;
final int TYPE_MULTIPLY = 3;
final int TYPE_RANDOM = 4;
final int TYPE_POWER = 5;
final int TYPE_FIBONACCI = 6;
String beginRow = " * |";
String divider = "-------";
int count = 1;
public IntTable(){
}
public IntTable(int row, int column, int type){
}
public int getRow(){
return row;
}
public int getColumn(){
return column;
}
public int getType(){
return type;
}
public void setRow(int newRow){
row = newRow;
}
public void setColumn(int newColumn){
column = newColumn;
}
public void setType(int newType){
type = newType;
}
public void printTable(){
int count = 1;
printTableHeader();
for(int i = 1; i <row+1; i++){
System.out.printf("%4d %4s", i, " |");
for (int j = 1; j < column+1; j++)
{
System.out.printf("%4d", count);
count++;
}
System.out.println();
}
}
private void printTableHeader(){
for(int i = 1; i < column + 1; i++)
{
beginRow+=" "+i;
divider+="-----";
}
System.out.println(beginRow);
System.out.println(divider);
}
private void printTableRowID(int ID){
ID = row;
for(int i = 1; i <ID+1; i++){
System.out.printf("%4d %4s", i, " |");
System.out.print(getElement(i, (row-(row-1))));
System.out.println();
}
}
private int getElement(int c, int r){
if(type == 0)
return 0;
else if(type == 1)
return c+column;
else if(type == 2)
return c+ r;
else if(type == 3)
return c*r;
else if(type == 4)
return (int)(1 + Math.random()*10);
else if(type == 5)
return (int)Math.pow(r, c);
else
return r;
}
private int pow(int one, int two){
return (int)Math.pow(one, two);
}
private int fibonacci(int fib){
return fib;
}
private int sum(int add, int addd){
return add + addd;
}
private int multiply(int prod, int product){
return prod * product;
}
private int random(int what, int huh){
return (int)(what + Math.random()*huh);
}
}

the reason why header repeating is because you do not reinitialize variable(beginRow and divider)
when you call printTable Method, variable String beginRow = " * |"; String divider = "-------"; is redefined
you need to reintialize variable(beginRow, divider)
look fllowing code which i modified
private void printTableHeader()
{
for(int i = 1; i < column + 1; i++)
{
beginRow+=" "+i;
divider+="-----";
}
System.out.println(beginRow);
System.out.println(divider);
beginRow = " * |";
divider = "-------";
}

Method Not Displaying Properly

The method "aboveAverage" in the following code is not displaying correctly and I've tried everything I can. Could someone please explain what's going wrong?
My code:
import java.util.*;
public class DailyCatch
{
private int fishermanID, fisherID;
private String dateOfSample, date;
private double[] fishCaught = new double[10];
private int currWeight = 0;
private String summary;
private double average;
private int aboveAvg;
public DailyCatch() { }
public DailyCatch (int fishermanID, String dateOfSample)
{
fisherID = fishermanID;
date = dateOfSample;
}
public DailyCatch (int fishermanID, String dateOfSample, String weight)
{
this(fishermanID, dateOfSample);
readWeights(weight);
}
public void addFish(double weight)
{
if (currWeight > 10)
{
// array full
}
else
{
fishCaught[currWeight] = weight;
currWeight += 1; // update current index of array
}
}
private void readWeights(String weightsAsString)
{
String[] weightsRead = weightsAsString.split("\\s+");
for (int i = 0; i < weightsRead.length; i++)
{
this.addFish(Double.parseDouble(weightsRead[i]));
}
}
public String toString()
{
return "Fisherman ID: " + fisherID + "\nDate:" + date + "\nFish Caught with Weights: " + Arrays.toString(fishCaught);
}
public void printWeights()
{
for (int i = 0; i < fishCaught.length; i++)
{
System.out.println(fishCaught[i]);
}
}
public double averageWeight()
{
double sum = 0;
double count = 0;
for (int i = 0; i < fishCaught.length; i++)
{
if (fishCaught[i] != 0)
{
sum += fishCaught[i];
count += 1;
average = sum/count;
}
}
return average;
}
public String getSummary()
{ int storyTellerCount = 0;
int keeperCount = 0;
int throwBackCount = 0;
for (int i = 0; i < fishCaught.length; i++)
{
if (fishCaught[i] > 5)
{
storyTellerCount++;
}
else if (fishCaught[i] >=1 && fishCaught[i] <= 5)
{
keeperCount++;
}
else if (fishCaught[i] < 1 && fishCaught[i] > 0)
{
throwBackCount++;
}
} String summary = ("\nStoryteller - " + storyTellerCount+ "\nKeeper - " + keeperCount + "\nThrowback - " + throwBackCount);
return summary;
}
public int aboveAverage()
{
int greatAvgCount = 0;
for (int i = 0; i < fishCaught.length; i++)
{
if (fishCaught[i] > average)
{
aboveAvg = greatAvgCount++;
}
}
return aboveAvg;
}
}
Test Code:
public class BigBass
{
public static void main (String[]args)
{
//Part 1
DailyCatch monday1 = new DailyCatch(32, "4/1/2013", "4.1 5.5 2.3 0.5 4.8 1.5");
System.out.println(monday1);
//Part 2
DailyCatch monday2 = new DailyCatch(44, "4/1/2013");
System.out.println(monday2);
monday2.addFish(2.1);
monday2.addFish(4.2);
System.out.println(monday2);
//Part 3
System.out.println("\n\nSUMMARY OF FISHERMAN 32");
System.out.println(monday1.getSummary());
//Part 4
double avg = monday1.averageWeight();
System.out.printf("\nThere are %d fish above the average weight of %.1f.", monday1.aboveAverage(), avg);
}
}
I just need to get Part 4 to work here. What it does is return that there have been 2 fish caught that are above average when I know it should be 3. The average is 3.1.

A simple mistake.
public int aboveAverage() {
int greatAvgCount = 0;
for (int i = 0; i < fishCaught.length; i++) {
if (fishCaught[i] > 3.1) {
greatAvgCount++; // no 'return'
}
}
return greatAvgCount;
}

if (fishCaught[i] > 3.1)
{
return greatAvgCount++;
}
First try : 4.1 > 3.1
true
returns 0 ++ which is 0 basically
You can increment the counter inside the loop and keep the return statement for the end only.

try
public int aboveAverage() {
int greatAvgCount = 0;
for (int i = 0; i < fishCaught.length; i++) {
if (fishCaught[i] > 3.1) {
greatAvgCount++;
}
}
return greatAvgCount;
}

This line is your problem,
return greatAvgCount++;
you are incrimenting greatAvgCount then returning its initial value, there should be no "return" on this line
The aboveAverage method should be
public int aboveAverage()
{
int greatAvgCount = 0;
for (int i = 0; i < fishCaught.length; i++)
{
if (fishCaught[i] > 3.1)
{
greatAvgCount++;
}
}
return greatAvgCount;
}
Also, you may just be doing it for debug, in which case fair enough, but hardcoding the "average" as 3.1 is generally considered bad practice. If you want average to be always 3.1 (i.e. its a global average that you've looked up from a book then its more usual to declare a static variable called double AVERAGE=3.1 and then use that where ever average is required, that way if the "book value" changes you only need to change average in one place in your code. If average is calculated from your data obviously you should use the calculated value.
Also not directly related to your problem but why are you using an array for your caught fish with a predefined maximum of 10. If you used an ArrayList you could add to it as you saw fit and it would auto expand to accommodate
private double[] fishCaught = new double[10];
becomes
private ArrayList<Double> fishCaught = new ArrayList<Double>();