Any ideas what I am missing here? I am reading from a file array. The values in the text file don't get stored and there is no output. All I get is "names and totals" but no values.
I don't know.
private int[] totals;
private String[] names;
private String[] list;
private int count;
public void readData() throws IOException {
BufferedReader input = new BufferedReader(new FileReader("cookies.txt"));
//create the arrays
totals = new int[count];
names = new String[count];
list = new String[count];
//read in each pair of values
String quantityString = input.readLine();
for (int i = 0; i < count; i++) {
names[i] = input.readLine();
list[i] = input.readLine();
quantityString = input.readLine();
totals[i] = Integer.parseInt(quantityString);
}
}
public void display() {
System.out.println("names totals")
for (int i = 0; i < count; i++)
System.out.println(list[i] + " \t " + names[i] + " \t" + totals[i]);
}
//called to compute and print the result
public void printResults() {
//find the best teacher
int maxIndex = 0;
int maxValue = 0;
//for each record stores
for (int i = 0; i < count; i++) {
//if we have a new MAX value so far, update variables
if (maxValue < totals[i]) {
maxValue = totals[i];
maxIndex = i;
}
}
}
You never give the variable count a value, so it initialized to 0 by Java. This means that your arrays are of size 0 also.
So since count is zero, you never read anything from the file, which is why nothing is stored in your arrays and also why nothing is printed out.
Example: Reading a File line-by-line
// create temporary variable to hold what is being read from the file
String line = "";
// when you don't know how many things you have to read in use a List
// which will dynamically grow in size for you
List<String> names = new ArrayList<String>();
List<Integer> values = new ArrayList<Integer>();
// create a Reader, to read from a file
BufferedReader input = new BufferedReader(new FileReader("cookies.txt"));
// read a full line, this means if you line is 'Smith 36'
// you read both of these values together
while((line = input.readLine()) != null)
{
// break 'Smith 36' into an array ['Smith', '36']
String[] nameAndValue = line.split("\\s+");
names.add(nameAndValue[0]); // names.add('Smith')
values.add(Integer.parseInt(nameAndValue[1]); // values.add(36);
}
Related
I am creating a program that is reading a file of names and ages then printing them out in ascending order. I am parsing through the file to figure out the number of name age pairs and then making my array that big.
The input file looks like this:
(23, Matt)(2000, jack)(50, Sal)(47, Mark)(23, Will)(83200, Andrew)(23, Lee)(47, Andy)(47, Sam)(150, Dayton)
When I am running my code I get the output of (0,null) and I am not sure why. I have been trying to fix it for a while and am lost. If anyone can help that would be great My code is below.
public class ponySort {
public static void main(String[] args) throws FileNotFoundException {
int count = 0;
int fileSize = 0;
int[] ages;
String [] names;
String filename = "";
Scanner inputFile = new Scanner(System.in);
File file;
do {
System.out.println("File to read from:");
filename = inputFile.nextLine();
file = new File(filename);
//inputFile = new Scanner(file);
}
while (!file.exists());
inputFile = new Scanner(file);
if (!inputFile.hasNextLine()) {
System.out.println("No one is going to the Friendship is magic Party in Equestria.");
}
while (inputFile.hasNextLine()) {
String data1 = inputFile.nextLine();
String[] parts1 = data1.split("(?<=\\))(?=\\()");
for (String part : parts1) {
String input1 = part.replaceAll("[()]", "");
Integer.parseInt(input1.split(", ")[0]);
fileSize++;
}
}
ages = new int[fileSize];
names = new String[fileSize];
while (inputFile.hasNextLine()) {
String data = inputFile.nextLine();
String[] parts = data.split("(?<=\\))(?=\\()");
for (String part : parts) {
String input = part.replaceAll("[()]", "");
ages[count] = Integer.parseInt(input.split(", ")[0]);
names[count] = input.split(", ")[1];
count++;
}
}
ponySort max = new ponySort();
max.bubbleSort(ages, names, count);
max.printArray(ages, names, count);
}
public void printArray(int ages[], String names[], int count) {
System.out.print("(" + ages[0] + "," + names[0] + ")");
// Checking for duplicates in ages. if it is the same ages as one that already was put in them it wont print.
for (int i = 1; i < count; i++) {
if (ages[i] != ages[i - 1]) {
System.out.print("(" + ages[i] + "," + names[i] + ")");
}
}
}
public void bubbleSort(int ages[], String names[], int count ){
for (int i = 0; i < count - 1; i++) {
for (int j = 0; j < count - i - 1; j++) {
// age is greater so swaps age
if (ages[j] > ages[j + 1]) {
// swap the ages
int temp = ages[j];
ages[j] = ages[j + 1];
ages[j + 1] = temp;
// must also swap the names
String tempName = names[j];
names[j] = names[j + 1];
names[j + 1] = tempName;
}
}
}
}
}
output example
File to read from:
file.txt
(0,null)
Process finished with exit code 0
What your code does is to Scan the file twice.
In the first loop you do
String data1 = inputFile.nextLine();
Code reads first line and then scanner goes to the next (second) line.
Later you do again inputFile.nextLine(); The second line is empty and the code never goes into the second loop and content is never read.
If you can use Lists, you should create two array lists and add ages and names into the arraylists in the first scan, so you scan the file once. When done, you could get the Array out of the arraylist.
If you should only use arrays and you want a simple update, just add another Scanner before the second loop:
ages = new int[fileSize];
names = new String[fileSize];
inputFile = new Scanner(file); // add this line
I'm having some trouble accessing my 2D array (myArray) outside of this the loop. I want to access it using other methods, but I can't even access it in this method. It prints out correctly as it's looping, but the test print of
System.out.println(myArray[10][2]);
is always null. So it's like the array isn't actually filling or something. Anyone know what I'm doing wrong here?
package titanic;
import java.io.*;
import java.util.*;
public class Titanic {
public static final int ROW = 1309;
public static final int COLUMN = 6;
public static String [][] myArray = new String[ROW][COLUMN];
public static String[][] arraySetup(){
int recordCounter = 0;
String[][] myArray = new String[ROW][COLUMN];
String[] name = new String [ROW];
try {
BufferedReader br = new BufferedReader(new FileReader("C:/Users/Tom/Desktop/Titanic.txt"));
String line;
for (int i = 0; i < 1309; i++){
while((line = br.readLine()) != null){
String tmp[] = line.split("\t");
myArray[i][0] = tmp[0];
myArray[i][1] = tmp[1];
myArray[i][2] = tmp[2];
myArray[i][3] = tmp[3];
myArray[i][4] = tmp[4];
myArray[i][5] = tmp[5];
System.out.println("myArray[i][5] = " + myArray[i][5]);
recordCounter++;
}
}
} catch (IOException e) {
e.printStackTrace();
}
System.out.println(myArray[10][2]);
System.out.println(recordCounter + " records.");
return myArray;
}
As you have you while loop inside for loop that is used to for indexing your output array while loop always writes into the myArray[0][0] to myArray[0][5]
for (int i = 0; i < 1309; i++){ // i is 0
while((line = br.readLine()) != null){ // you go through all the lines while i is 0
String tmp[] = line.split("\t");
myArray[i][0] = tmp[0];
myArray[i][1] = tmp[1];
myArray[i][2] = tmp[2];
myArray[i][3] = tmp[3];
myArray[i][4] = tmp[4];
myArray[i][5] = tmp[5];
System.out.println("myArray[i][5] = " + myArray[i][5]);
recordCounter++;
}
}
Because of that your check always returns null.
System.out.println(myArray[10][2]);
I think the problem in your code is right there
for (int i = 0; i < 1309; i++){ // you loop 1308 time
while((line = br.readLine()) != null){ /* in each loop, you loop
until you have read all the file so you read 1308 time the file. But when
you reach the end of file on the first iterration, it wont read the file on the 1307
other iterration and all data will be store in myArray[0][0-5]*/
String tmp[] = line.split("\t");
myArray[i][0] = tmp[0];
myArray[i][1] = tmp[1];
myArray[i][2] = tmp[2];
myArray[i][3] = tmp[3];
myArray[i][4] = tmp[4];
myArray[i][5] = tmp[5];
System.out.println("myArray[i][5] = " + myArray[i][5]);
recordCounter++;
}
}
Don't use for and while loop together. During the first for loop, your while reads all file contents and all other array positions remain empty.
Try this instead:
int i=0;
while ((line = br.readLine()) != null){
String tmp[] = line.split("\t");
myArray[i][0] = tmp[0];
myArray[i][1] = tmp[1];
...
myArray[i][5] = tmp[5];
i++;
System.out.println("myArray[i][5] = " + myArray[i][5]);
recordCounter++;
}
I'd like to know how to figure out the rows and columns of a passed textfile.
Suppose the textfile looks like this:
X...................
....................
....................
....................
....................
....................
....................
....................
....................
..X.................
This textfile has 10 rows and 20 columns and I'm facing troubles with how to get those rows and columns for my constructor (DONT WORRY ABOUT "X" symbols). I just would like to know how to get rows and columns from the textfile/ would like to know how to figure out how big the map is.
I need help with the second constructor in the code:
import java.util.Scanner; // Required to get input
import java.io.File; // Required to get input from files
// A 2D treasure map which stores locations of treasures in an array
// of coordinates
public class TreasureMap{
int rows, cols; // How big is the treasure map
Coord [] treasureLocations; // The locations of treasures
Scanner kbd = new Scanner(System.in);
// Prompt the user for info on the treasure map and then create it
public TreasureMap(){
int numberOfTreasures = 0;
System.out.println("Enter map size (2 ints): ");
rows = kbd.nextInt(); cols = kbd.nextInt();
System.out.println("Enter number of treasures (1 int): ");
numberOfTreasures = kbd.nextInt();
treasureLocations = new Coord[numberOfTreasures];
for (int i = 0; i < numberOfTreasures; i++)
{
System.out.println("Enter treasure " + i + " location (2 ints): ");
rows = kbd.nextInt(); cols = kbd.nextInt();
treasureLocations[i] = new Coord(rows, cols);
}
}
// Read the string representation of a map from a file
public TreasureMap(String fileName) throws Exception{
Scanner data = new Scanner(new File(fileName));
int counter = 0;
while(data.hasNextLine())
{
counter++;
}
}
// true if there is treasure at the given (r,c) coordinates, false
// otherwise
// This method does not require modification
public boolean treasureAt(int r, int c){
for(int i=0; i<treasureLocations.length; i++){
Coord coord = treasureLocations[i];
if(coord.row == r && coord.col == c){
return true;
}
}
return false;
}
// Create a string representation of the treasure map
public String toString(){
String [][] map = new String[this.rows][this.cols];
for(int i=0; i<rows; i++){
for(int j=0; j<cols; j++){
map[i][j] = ".";
}
}
for(int i=0; i<treasureLocations.length; i++){
Coord c = treasureLocations[i];
map[c.row][c.col] = "X";
}
StringBuilder sb = new StringBuilder();
for(int i=0; i<rows; i++){
for(int j=0; j<cols; j++){
sb.append(map[i][j]);
}
sb.append("\n");
}
return sb.toString();
}
}
Here's some code you can use to read lines from a file:
File file = new File(fileName);
try (BufferedReader br = new BufferedReader(new FileReader(file))) {
String line;
int rows = 0;
int cols = 0;
while ((line = br.readLine()) != null) {
// process the line
rows++;
cols = line.length(); // always the size of the last line in the file
}
}
br.close();
Based on your implementation, this would give you width and height of your input file.
public TreasureMap(String fileName) throws Exception{
Scanner data = new Scanner(new File(fileName));
int width = 0;
int height = 0;
while(data.hasNextLine())
{
String line = data.nextLine();
width = Math.max(width, line.length());
height++;
}
System.out.println(width + " x " + height);
}
I want to search in an arraylist from a user input but my if condition doesn't seem to work. Using boolean and .contains() doesn't work for my programme either. This is the coding:
String phone;
phone=this.text1.getText();
System.out.println("this is the phone: " + phone);
BufferedReader line = new BufferedReader(new FileReader(new File("C:\\Users\\Laura Sutardja\\Documents\\IB DP\\Computer Science HL\\cs\\data.txt")));
String indata;
ArrayList<String[]> dataArr = new ArrayList<String[]>();
while ((indata = line.readLine()) != null) {
String[] club = new String[2];
String[] value = indata.split(",", 2);
//for (int i = 0; i < 2; i++) {
int n = Math.min(value.length, club.length);
for (int i = 0; i < n; i++) {
club[i] = value[i];
}
boolean aa = dataArr.contains(this.text1.getText());
if(aa==true)
text2.setText("The data is found.");
else
text2.setText("The data is not found.");
dataArr.add(club);
}
for (int i = 0; i < dataArr.size(); i++) {
for (int x = 0; x < dataArr.get(i).length; x++) {
System.out.printf("dataArr[%d][%d]: ", i, x);
System.out.println(dataArr.get(i)[x]);
}
}
}
catch ( IOException iox )
{
System.out.println("Error");
}
Your dataArr is a list of String[], and you are searching for a String. The two are different kind of objects.
I don't really know how the content of the club array looks like, but you should either change dataArr in order to hold plain String, or to write a method which looks iteratively in dataArr for a String[] containing the output of this.text1.getText().
There is a lot wrong with the program. I assume you want to read a textfile and store each line in the arraylist. To do this you have to split each line of the textfile and store that array in the arrayList.
String[] value;
while ((indata = line.readLine()) != null) {
value = indata.split(",");
dataArr.add(value);
}
Now you have the contents of the file in the arrayList.
Next you want to compare the userinput with each element of the arraylist.
int j = 0;
for (int i = 0; i < dataArr.size(); i++) {
String[] phoneData = dataArr.get(i);
if (phoneData[1].equals(phone)) { // i am assuming here that the phone number is the 2nd element of the String[] array, since i dont know how the textfile looks.
System.out.println("Found number.");
club[j++] = phoneData[1];
} else if (i == dataArr.size()-1) {
System.out.println("Didn't find number.");
}
}
Edit:
As requested:
String phone;
phone = "38495";
System.out.println("this is the phone: " + phone);
BufferedReader line = new BufferedReader(new FileReader(new File("list.txt")));
String indata;
ArrayList<String[]> dataArr = new ArrayList<>();
String[] club = new String[2];
String[] value;// = indata.split(",", 2);
while ((indata = line.readLine()) != null) {
value = indata.split(",");
dataArr.add(value);
}
int j = 0;
for (int i = 0; i < dataArr.size(); i++) {
String[] phoneData = dataArr.get(i);
if (phoneData[1].equals(phone)) {
System.out.println("Found number.");
club[j++] = phoneData[1];
break;
} else if (i == dataArr.size()-1) {
System.out.println("Didn't find number.");
}
}
I hope this makes sense now.
I have a method that is suppose to take 3 arrays and save them to a txt file. But it doesnt print to the list. Here is my code for the method
public static void saveAndExit(int count, String[] makeArray, String[] moduleArray, double [] msrpArray) throws IOException{
File carList = new File("cars_list.txt");
PrintWriter pw = new PrintWriter(carList);
int index = 0;
String[] finalMSRPArray = new String[12];
for (int i = 0; i < msrpArray.length; i++){
finalMSRPArray[i] = String.valueOf(msrpArray[i]);
}
while(count < makeArray.length && count < moduleArray.length && count < msrpArray.length){
pw.write(makeArray[index]+"\n");
pw.write(moduleArray[index]+"\n");
pw.write(finalMSRPArray[index]+"\n");
index++;
}
pw.close();
}
Any help is much appreciated!