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How to solve class case exception ? Using arraylist [closed]

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I am trying to make a program that capable to add new participant and save it in txt file .The program also able to read data from txt file and do processes . The program can run , but when I try to display participants by state . I get java.lang.ClassCastException : java.lang.String cannot be cast to Reading . Trying several thing but still can't figure it out
import java.util.* ;
import java.io.* ;
class KRBApp{
public static int menu(){
Scanner sc = new Scanner(System.in);
System.out.println("\n\n\n\t\t\tKRB APPLICATION MAIN MENU");
System.out.println("\t\t\t~~~~~~~~~");
System.out.println("\n\t\t\t1. Add new participant");
System.out.println("\t\t\t2. Display participants by state");
System.out.println("\t\t\t3. Search participants by name");
System.out.println("\t\t\t4. Exit");
System.out.print("\n\t\t\t>>> ");
int ch = Integer.parseInt(sc.nextLine());
return ch;
}//menu
public static void main(String []args)throws FileNotFoundException, IOException{
Scanner sc = new Scanner(System.in);
ArrayList pList = new ArrayList();
FileReader fr1 = new FileReader("data.txt");
BufferedReader br1 = new BufferedReader(fr1);
String read= br1.readLine();
while(read!= null){ //read file io
StringTokenizer st = new StringTokenizer(read,";");
String name = st.nextToken();
String phone = st.nextToken();
String ic = st.nextToken();
Reading reading = new Reading(name,phone,ic);
pList.add(read);
read = br1.readLine();
}//while
Reading reading = null;
File fi1 = new File("data.txt");
FileWriter fw1 = new FileWriter(fi1,true);
BufferedWriter bw1 = new BufferedWriter(fw1);
PrintWriter pw1 = new PrintWriter(bw1);
int ch = 0;
do{
ch = menu();
if(ch == 1){ // add new participant
System.out.print("Enter Name : ");
String name = sc.nextLine();
System.out.print("Enter Phone Number : " );
String noTel = sc.nextLine();
System.out.print("Enter IC Number : ");
String noIC = sc.nextLine();
System.out.println(); //new line for each data
Participant pt = new Participant( name,noTel,noIC);
pw1.println(pt.toFile());
}
else if(ch == 2){ // search by state
for(int i = 0; i < pList.size() ; i++){
reading = (Reading)pList.get(i); // error here
System.out.print(reading.getName());
}
}
else if(ch == 3){ //sort by name
//call method ...
}
}while(ch != 4);
System.out.print("\n\n\n\t\t\tThank You and See You Again! ");
//close
pw1.close();
}//public
}//class
Reading class to read data from file io
class Reading {
private String name;
private String phone;
private String ic;
public Reading ( String name , String phone , String ic ){
this.name = name;
this.phone = phone;
this.ic = ic;
}
public String getName() { return name;}
public String getPhone() {return phone;}
public String getIc() { return ic; }
public String displayAll(){
return "Name : "+ name + "\n" + "Phone numbers : " +phone + "\n" + "Ic : " +ic + "/n" ;
}
}//class
Here Participant class use to send data to file io
class Participant {
private String name;
private String noTel;
private String noIC;
public Participant ( String name , String noTel , String noIC ){
this.name = name;
this.noTel = noTel;
this.noIC = noIC;
}
public String toFile(){
return name+";"+ noTel + ";" + noIC ;
}//toFile
}//class

First, your pList is a raw-type. That is causing it to ignore your second issue, where you add the wrong variable to the List. Change
ArrayList pList = new ArrayList();
to
List<Reading> pList = new ArrayList<>();
and change
Reading reading = new Reading(name,phone,ic);
pList.add(read);
to
Reading reading = new Reading(name,phone,ic);
pList.add(reading);

Is there any way to store the elements present in the file to the to the array of the object in java

The program is giving correct output when System.out.println(mem[i].memName); but the array of class "member" is giving output (alex alex alex alex) i.e of the last line of the file (mentioned at the END of the CODE)
it should give all the names listed in the file.
import java.io.*;
import java.util.*;
class member//CLASS TO BE USED AS ARRAY TO STORE THE PRE REGISTERED MEMBERS FED INSIDE
{ //THE FILE "member.txt"
static int memId;
static String memName, memEmail, memPh, date;
}
public class entry// file name
{
static DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy/MM/dd");
static LocalDateTime now = LocalDateTime.now();
static Scanner input = new Scanner(System.in);
static member[] mem = new member[100];
static trainer[] tr = new trainer[100];
static FileWriter fwriter = null;
static BufferedWriter bwriter = null;
static FileReader fread = null;
static BufferedReader bread = null;
static void memberEntry() {
int i = 0;
System.out.println("NEW MEMBER IS BEING ADDED");
try {
fwriter = new FileWriter("C:\\Users\\itisa\\OneDrive\\Desktop\\GYM
PROJECT\\member.txt
",true);
bwriter = new BufferedWriter(fwriter);
System.out.println("Member ID is being automatically genrated");
int autoID = 101 + getMemberRecords();//Fetching the number of members so that ID can
//Be genrated automatically
i = autoID % 100;//jumping toward the next loaction location
System.out.println("Member ID of new member is" + autoID);
mem[i].memId = autoID;
System.out.print("Enter the name of the member:");
mem[i].memName = input.next();
System.out.print("Enter the email address of memeber:");
mem[i].memEmail = input.next();
System.out.print("Enter the contact number of memeber:");
mem[i].memPh = input.next();
System.out.println("Date has been feeded automatically:" + dtf.format(now));
mem[i].date = dtf.format(now);
bwriter.write(String.valueOf(mem[i].memId));
bwriter.write("|");
bwriter.write(mem[i].memName);
bwriter.write("|");
bwriter.write(mem[i].memEmail);
bwriter.write("|");
bwriter.write(mem[i].memPh);
bwriter.write("|");
bwriter.write(mem[i].date);
bwriter.write("\n");
System.out.println("MEMBER CREATED SUCCESSFULLY");
System.out.println("---------------------------------------");
bwriter.close();
} catch (IOException e) {
System.out.print(e);
}
}
static int getMemberRecords() {
int count = 0, i = 0;
try {
fread = new FileReader("C:\\Users\\itisa\\OneDrive\\Desktop\\GYM PROJECT\\member.txt");
bread = new BufferedReader(fread);
String lineRead = null;
while ((lineRead = bread.readLine()) != null)//Just to get to know the number of member
//alreadyinside the file
{
String[] t = lineRead.split("\\|");
mem[i].memId = Integer.parseInt(t[0]);
mem[i].memName = t[1];
mem[i].memEmail = t[2];
mem[i].memPh = t[3];
mem[i].date = t[4];
i++;
count++;
}
System.out.println(mem[0].memName);//should print the 1st name present in the name
//i.e, RAVI
} catch (IOException e) {
System.out.println(e);
}
return count;
}
public static void main(String[] args) throws IOException {
System.out.println("Total number of accounts:" + getMemberRecords());
}
}
Elements stored in the file:
101|RAVI|itisadi23#gmai.com|9102019656|2020/04/30
102|aditya|adi#gmail.com|9386977983|2020/04/30
103|anurag|anu#ymail.com|10000000000|2020/04/30
104|alex|alex123#mail.com|2829578303|2020/04/30
Expected output:
RAVI
Total number of accounts = 4
My output:
alex
Total number of accounts=4
In Short it is giving last name as output no matter what index number is given to fetch the data.

Your member class members must not be static, if they are, they're shared by every member class object.
The other problem is that your member array nodes are not being initialized, you'll need:
Live demo
class member
{
int memId; //non-static
String memName, memEmail, memPh, date; //non-static
}
and
//...
while ((lineRead = bread.readLine()) != null) {
String[] t = lineRead.split("\\|");
mem[i] = new member(); // initialize every node
mem[i].memId = Integer.parseInt(t[0]);
mem[i].memName = t[1];
mem[i].memEmail = t[2];
mem[i].memPh = t[3];
mem[i].date = t[4];
i++;
count++;
}
System.out.println(mem[0].memName);
//...
Output:
RAVI
Note that you can use ArrayList or other java collection.

Specified text file not found for File I/O in Eclipse

I am trying to do a file I/O in eclipse. Here is the code:
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.StringTokenizer;
public class TextDB {
public static final String SEPARATOR = "|";
// an example of reading
public static ArrayList readProfessors(String filename) throws IOException {
// read String from text file
ArrayList stringArray = (ArrayList) read(filename);
ArrayList alr = new ArrayList();// to store Professors data
for (int i = 0; i < stringArray.size(); i++) {
String st = (String) stringArray.get(i);
// get individual 'fields' of the string separated by SEPARATOR
StringTokenizer star = new StringTokenizer(st, SEPARATOR); // pass in the string to the string tokenizer using delimiter ","
String name = star.nextToken().trim(); // first token
String email = star.nextToken().trim(); // second token
int contact = Integer.parseInt(star.nextToken().trim()); // third token
// create Professor object from file data
Professor prof = new Professor(name, email, contact);
// add to Professors list
alr.add(prof);
}
return alr;
}
// an example of saving
public static void saveProfessors(String filename, List al) throws IOException {
List alw = new ArrayList();// to store Professors data
for (int i = 0; i < al.size(); i++) {
Professor prof = (Professor) al.get(i);
StringBuilder st = new StringBuilder();
st.append(prof.getName().trim());
st.append(SEPARATOR);
st.append(prof.getEmail().trim());
st.append(SEPARATOR);
st.append(prof.getContact());
alw.add(st.toString());
}
write(filename, alw);
}
/**
* Write fixed content to the given file.
*/
public static void write(String fileName, List data) throws IOException {
PrintWriter out = new PrintWriter(new FileWriter(fileName));
try {
for (int i = 0; i < data.size(); i++) {
out.println((String) data.get(i));
}
} finally {
out.close();
}
}
/**
* Read the contents of the given file.
*/
public static List read(String fileName) throws IOException {
List data = new ArrayList();
Scanner scanner = new Scanner(new FileInputStream(fileName));
try {
while (scanner.hasNextLine()) {
data.add(scanner.nextLine());
}
} finally {
scanner.close();
}
return data;
}
public static void main(String[] aArgs) {
TextDB txtDB = new TextDB();
String filename = "professor.txt";
try {
// read file containing Professor records.
ArrayList al = TextDB.readProfessors(filename);
for (int i = 0; i < al.size(); i++) {
Professor prof = (Professor) al.get(i);
System.out.println("Name " + prof.getName());
System.out.println("Contact " + prof.getContact());
}
Professor p1 = new Professor("Joseph", "jos#ntu.edu.sg", 67909999);
// al is an array list containing Professor objs
al.add(p1);
// write Professor record/s to file.
TextDB.saveProfessors(filename, al);
} catch (IOException e) {
System.out.println("IOException > " + e.getMessage());
}
}
}
And my Professor class:
import java.io.Serializable;
public class Professor implements Serializable {
private String name;
private String email;
private int contact;
public Professor(String n, String e, int c) {
name = n;
email = e;
contact = c;
}
public String getName() {
return name;
}
public int getContact() {
return contact;
}
public String getEmail() {
return email;
}
public boolean equals(Object o) {
if (o instanceof Professor) {
Professor p = (Professor) o;
return (getName().equals(p.getName()));
}
return false;
}
}
However, when I run it, the compiler told the the specified file "professor.txt" is not found. I thought the compiler will create the text file automatically based on these code?
Thanks in advance.

Before attempting to read the file in your application, create it if it doesn't exist, either directly :
String filename = "professor.txt" ;
File file = new File(fileName);
if(!file.exists()){
file.createNewFile();
}
Or by calling your write method.
String filename = "professor.txt" ;
File file = new File(fileName);
if(!file.exists()){
TextDB.saveProfessors(filename, new ArrayList());
}
The PrintWriter will create the file for you, even though nothing is written to it (like with this empty list).

In your main you are firstly reading the file and then write it: if the file doesn't exist it will throw you the exception. Probably, the first time you ran it, the file was present (maybe you have write the code to write the file first and then you have launch it).
so, two solutions...
First: change the order of your main.
public static void main(String[] aArgs) {
TextDB txtDB = new TextDB();
String filename = "professor.txt";
try {
Professor p1 = new Professor("Joseph", "jos#ntu.edu.sg", 67909999);
// al is an array list containing Professor objs
al.add(p1);
// write Professor record/s to file.
TextDB.saveProfessors(filename, al);
// read file containing Professor records.
ArrayList al = TextDB.readProfessors(filename);
for (int i = 0; i < al.size(); i++) {
Professor prof = (Professor) al.get(i);
System.out.println("Name " + prof.getName());
System.out.println("Contact " + prof.getContact());
}
} catch (IOException e) {
System.out.println("IOException > " + e.getMessage());
}
}
Second: check if the file exist or not and then skip the read of it if it doesn't
public static void main(String[] aArgs) {
TextDB txtDB = new TextDB();
String filename = "professor.txt";
try {
//check if the file exist
File oFile = new File(filename);
if(oFile.exist()) {
// read file containing Professor records.
ArrayList al = TextDB.readProfessors(filename);
for (int i = 0; i < al.size(); i++) {
Professor prof = (Professor) al.get(i);
System.out.println("Name " + prof.getName());
System.out.println("Contact " + prof.getContact());
}
}
Professor p1 = new Professor("Joseph", "jos#ntu.edu.sg", 67909999);
// al is an array list containing Professor objs
al.add(p1);
// write Professor record/s to file.
TextDB.saveProfessors(filename, al);
} catch (IOException e) {
System.out.println("IOException > " + e.getMessage());
}
}
UPDATE after comment:
public static void main(String[] aArgs) {
TextDB txtDB = new TextDB();
String filename = "professor.txt";
try {
//check if the file exist
File oFile = new File(filename);
if(!oFile.exist()) {
oFile.mkdirs(); //optional
oFile.createNewFile();
}
// read file containing Professor records.
ArrayList al = TextDB.readProfessors(filename);
for (int i = 0; i < al.size(); i++) {
Professor prof = (Professor) al.get(i);
System.out.println("Name " + prof.getName());
System.out.println("Contact " + prof.getContact());
}
Professor p1 = new Professor("Joseph", "jos#ntu.edu.sg", 67909999);
// al is an array list containing Professor objs
al.add(p1);
// write Professor record/s to file.
TextDB.saveProfessors(filename, al);
} catch (IOException e) {
System.out.println("IOException > " + e.getMessage());
}
}

Scanner from file doesn't seem to be reading file

I'm doing a Phone Directory project and we have to read from a directory file telnos.txt
I'm using a Scanner to load the data from the file telnos.txt, using a loadData method from a previous question I asked here on StackOverflow.
I noticed attempts to find a user always returned Not Found, so I added a few System.out.printlns in the methods to help me see what was going on. It looks like the scanner isn't reading anything from the file. Weirdly, it is printing the name of the file as what should be the first line read, which makes me think I've missed something very very simple here.
Console
run:
telnos.txt
null
loadData tested successfully
Please enter a name to look up: John
-1
Not found
BUILD SUCCESSFUL (total time: 6 seconds)
ArrayPhoneDirectory.java
import java.util.*;
import java.io.*;
public class ArrayPhoneDirectory implements PhoneDirectory {
private static final int INIT_CAPACITY = 100;
private int capacity = INIT_CAPACITY;
// holds telno of directory entries
private int size = 0;
// Array to contain directory entries
private DirectoryEntry[] theDirectory = new DirectoryEntry[capacity];
// Holds name of data file
private final String sourceName = "telnos.txt";
File telnos = new File(sourceName);
// Flag to indicate whether directory was modified since it was last loaded or saved
private boolean modified = false;
// add method stubs as specified in interface to compile
public void loadData(String sourceName) {
Scanner read = new Scanner("telnos.txt").useDelimiter("\\Z");
int i = 1;
String name = null;
String telno = null;
while (read.hasNextLine()) {
if (i % 2 != 0)
name = read.nextLine();
else
telno = read.nextLine();
add(name, telno);
i++;
}
}
public String lookUpEntry(String name) {
int i = find(name);
String a = null;
if (i >= 0) {
a = name + (" is at position " + i + " in the directory");
} else {
a = ("Not found");
}
return a;
}
public String addChangeEntry(String name, String telno) {
for (DirectoryEntry i : theDirectory) {
if (i.getName().equals(name)) {
i.setNumber(telno);
} else {
add(name, telno);
}
}
return null;
}
public String removeEntry(String name) {
for (DirectoryEntry i : theDirectory) {
if (i.getName().equals(name)) {
i.setName(null);
i.setNumber(null);
}
}
return null;
}
public void save() {
PrintWriter writer = null;
// writer = new PrintWriter(FileWriter(sourceName));
}
public String format() {
String a;
a = null;
for (DirectoryEntry i : theDirectory) {
String b;
b = i.getName() + "/n";
String c;
c = i.getNumber() + "/n";
a = a + b + c;
}
return a;
}
// add private methods
// Adds a new entry with the given name and telno to the array of
// directory entries
private void add(String name, String telno) {
System.out.println(name);
System.out.println(telno);
theDirectory[size] = new DirectoryEntry(name, telno);
size = size + 1;
}
// Searches the array of directory entries for a specific name
private int find(String name) {
int result = -1;
for (int count = 0; count < size; count++) {
if (theDirectory[count].getName().equals(name)) {
result = count;
}
System.out.println(result);
}
return result;
}
// Creates a new array of directory entries with twice the capacity
// of the previous one
private void reallocate() {
capacity = capacity * 2;
DirectoryEntry[] newDirectory = new DirectoryEntry[capacity];
System.arraycopy(theDirectory, 0, newDirectory,
0, theDirectory.length);
theDirectory = newDirectory;
}
}
ArrayPhoneDirectoryTester.java
import java.util.Scanner;
public class ArrayPhoneDirectoryTester {
public static void main(String[] args) {
//create a new ArrayPhoneDirectory
PhoneDirectory newTest = new ArrayPhoneDirectory();
newTest.loadData("telnos.txt");
System.out.println("loadData tested successfully");
System.out.print("Please enter a name to look up: ");
Scanner in = new Scanner(System.in);
String name = in.next();
String entryNo = newTest.lookUpEntry(name);
System.out.println(entryNo);
}
}
telnos.txt
John
123
Bill
23
Hello
23455
Frank
12345
Dkddd
31231

In your code:
Scanner read = new Scanner("telnos.txt");
Is not going to load file 'telnos.txt'. It is instead going to create a Scanner object that scans the String "telnos.txt".
To make the Scanner understand that it has to scan a file you have to either:
Scanner read = new Scanner(new File("telnos.txt"));
or create a File object and pass its path to the Scanner constructor.
In case you are getting "File not found" errors you need to check the current working directory. You could run the following lines and see if you are indeed in the right directory in which the file is:
String workingDir = System.getProperty("user.dir");
System.out.println("Current working directory : " + workingDir);
You need to also catch the FileNotFoundException in the function as follows:
public void loadData(String sourceName) {
try {
Scanner read = new Scanner(new File("telnos.txt")).useDelimiter("\\Z");
int i = 1;
String name = null;
String telno = null;
while (read.hasNextLine()) {
if (i % 2 != 0)
name = read.nextLine();
else {
telno = read.nextLine();
add(name, telno);
}
i++;
}
}catch(FileNotFoundException ex) {
System.out.println("File not found:"+ex.getMessage);
}
}

You are actually parsing the filename not the actual file contents.
Instead of:
new Scanner("telnos.txt")
you need
new Scanner( new File( "telnos.txt" ) )
http://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html

Java FileNotFoundException error as statement not in a method

I have 2 files where 1(OrderCatalogue.java) reads in contents of a external file and 2(below). But I'm having the "FileNotFoundException must be caught or declard to be thrown" error for this line "OrderCatalogue catalogue= new OrderCatalogue();" and I understand that because its not in a method. But if i try puting it in a method, the code under the "getCodeIndex" and "checkOut" methods can't work with the error message of "package catalogue does not exist". Anyone has any idea how i can edit my code to make them work? Thank you!!
public class Shopping {
OrderCatalogue catalogue= new OrderCatalogue();
ArrayList<Integer> orderqty = new ArrayList<>(); //Create array to store user's input of quantity
ArrayList<String> ordercode = new ArrayList<>(); //Create array to store user's input of order number
public int getCodeIndex(String code)
{
int index = -1;
for (int i =0;i<catalogue.productList.size();i++)
{
if(catalogue.productList.get(i).code.equals(code))
{
index = i;
break;
}
}
return index;
}
public void checkout()
{
DecimalFormat df = new DecimalFormat("0.00");
System.out.println("Your order:");
for(int j=0;j<ordercode.size();j++)
{
String orderc = ordercode.get(j);
for (int i =0;i<catalogue.productList.size();i++)
{
if(catalogue.productList.get(i).code.equals(orderc))
{
System.out.print(orderqty.get(j)+" ");
System.out.print(catalogue.productList.get(i).desc);
System.out.print(" # $"+df.format(catalogue.productList.get(i).price));
}
}
}
}
And this is my OrderCatalogue file
public OrderCatalogue() throws FileNotFoundException
{
//Open the file "Catalog.txt"
FileReader fr = new FileReader("Catalog.txt");
Scanner file = new Scanner(fr);
while(file.hasNextLine())
{
//Read in the product details in the file
String data = file.nextLine();
String[] result = data.split("\\, ");
String code = result[0];
String desc = result[1];
String price = result[2];
String unit = result[3];
//Store the product details in a vector
Product a = new Product(desc, code, price, unit);
productList.add(a);
}

It seems the OrderCatalogue constructor throws FileNotFoundException. You can initialize catalogue inside Shopping constructor and catch the exception or declare it to throw FileNotFoundException.
public Shopping() throws FileNotFoundException
{
this.catalogue= new OrderCatalogue();
or
public Shopping()
{
try{
this.catalogue= new OrderCatalogue();
}catch(FileNotFoundException e)
blah blah
}