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Saving multiple input data in one .txt file. Is it possible to overwrite and get data from specific line?

Code first:
import java.io.*;
import java.util.Scanner;
public class Test {
public String date;
public String fridge1;
public String fridge2;
public String info;
static final int lineNumber = 0;
public Test(String date, String fridge1, String fridge2, String info) {
this.date = date;
this.fridge1 = fridge1;
this.fridge2 = fridge2;
this.info = info;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
public String getFridge1() {
return fridge1;
}
public void setFridge1(String fridge1) {
this.fridge1 = fridge1;
}
public String getFridge2() {
return fridge2;
}
public void setFridge2(String fridge2) {
this.fridge2 = fridge2;
}
public String getInfo() {
return info;
}
public void setInfo(String info) {
this.info = info;
}
#Override
public String toString() {
return
date + "\n" +
fridge1 + "\n" +
fridge2 + "\n" +
info + "\n";
}
public void saveData() {
File file = new File("text.txt");
boolean checker = true;
try (Scanner scanner = new Scanner(file)) {
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
if (line.contains(date)) {
checker = false;
break;
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
if (checker) {
try (FileOutputStream fos = new FileOutputStream("text.txt", true)) {
fos.write(toString().getBytes());
} catch (IOException e) {
e.printStackTrace();
}
} else {
...
}
}
}
import java.io.IOException;
public class Main {
public static void main(String[] args) throws IOException {
// Test test = new Test("19/02/1992", "10", "9", "ok");
// test.saveData();
Test test2 = new Test("19/02/1900", "8", "4", "not ok");
test2.saveData();
}
}
I want to do program in Java to get some inputs and date, mostly Strings. I just create a methods to write all data in one .txt file, one data - 1 line. If there is already existing date program is not writing new data. Finally, I would like to overwrite data. If I put the same date in, I would like to overwrite existing date to new one. So in my mind if I have in .txt file this data:
line1 17/05/16 line2 blabla line3 blabla line4 blabla
and I will put in Main this:
Test test2 = new Test("17/05/16", "8", "4", "not ok");
test2.saveData();
it should find where is 17/05/16 and then replace lines 2-4 like this.
line1 17/05/16
line2 8
line3 4
line4 not ok
It is possible? Then how to find out all data in reverse way? In mean when I would like to check my data from specific date ex. 17/05/16?
As you can see I just stuck in moment when I have to search where is my data. I can't find good methods.

When your program does start, your first step must always be reading whole text file into memory, line by line. Visit this page how you can achive it. Use your timestamp as key for the HashMap.
One advantage of HashMap is, you can easily check of occurences or add some data at the end. And if you want just update an existing entry, use the same key and the content will be overwritten.
After this, the next page demonstrate how to write the content back to your text file.
Please note: As I wrote in comment section the use of Spring Boot is a better option for your task.

Repeated Writing and Loading ArrayList of objects from a file

I have a 'Person' class where i stored data like name, surname etc. I make 5 object type Person, add them to ArrayList, and save this ArrayList to file. Next i'm loading from this file ArrayList and i have 5 person. Problem is when i want save again for example 10 object Person. When i'm loading ArrayList from file i'm getting only 5 person from first writing. If i repeat this still i will have load data from first writing to this file. How i can fix this ?
public class Data {
static List<Person> persons = new ArrayList<Person>();
public static void main(String[] args) throws IOException {
Data.savePersons(5);
Data.loadPersons();
/** Clean 'persons' array for TEST of load data */
persons.removeAll(persons);
System.out.println("\n-----------\nNext Round\n-----------\n");
Data.savePersons(10);
Data.loadPersons();
}
/** Save a couple of Person Object to file C:/data.ser */
public static void savePersons(int noOfPersonToSave) throws IOException {
FileOutputStream fout = null;
ObjectOutputStream oos = null;
/** Make 5 'Person' object and add them to ArrayList 'persons' for example */
for (int i = 0; i < noOfPersonToSave; i++) {
Person personTest = new Person("name" + i, "surname" + i, "email" +i, "1234567890" +i);
persons.add(personTest);
}
try {
fout = new FileOutputStream("C:\\data.ser", true);
oos = new ObjectOutputStream(fout);
oos.writeObject(persons);
System.out.println("Saving '" + persons.size() + "' Object to Array");
System.out.println("persons.size() = " + persons.size());
System.out.println("savePersons() = OK");
} catch (Exception ex) {
System.out.println("Saving ERROR: " + ex.getMessage());
} finally {
if (oos != null) {
oos.close();
}
}
}
/** Load previously saved a couple of Person Object in file C:/data.ser */
public static void loadPersons() throws IOException {
FileInputStream fis = null;
ObjectInputStream ois = null;
try {
fis = new FileInputStream("C:\\data.ser");
ois = new ObjectInputStream(fis);
persons = (List<Person>) ois.readObject();
//persons.add(result);
System.out.println("-------------------------");
System.out.println("Loading '" + persons.size() + "' Object from Array");
System.out.println("persons.size() = " + persons.size());
System.out.println("loadPersons() = OK");
} catch (Exception e) {
System.out.println("-------------------------");
System.out.println("Loading ERROR: " + e.getMessage());
} finally {
if (ois != null) {
ois.close();
}
}
}}
class Person implements Serializable {
private static final long serialVersionUID = 1L;
private String name;
private String surname;
private String mail;
private String telephone;
public Person(String n, String s, String m, String t) {
name = n;
surname = s;
mail = m;
telephone = t;
}
public String getName() {
return name;
}
public String getSurname() {
return surname;
}
public String getMail() {
return mail;
}
public String getTelephone() {
return telephone;
}}

new FileOutputStream("C:\\data.ser", true)
You're passing true for the append parameter. So you're appending a list of 10 persons to the file, after the already existing list of 5 people. And since you only read one list, you read the first you wrote, which contains 5 persons.
Pass false instead of true.

Reading A File and Storing It In An Object

I am trying to read from a file and store the contents into an object called ToDoList(from what I assume is under the GetItem method). Then I am supposed to allow the user to add on to the list. But I am lost on how to create the object and print it.
public class ToDoList {
private ToDoItem[] items;
ToDoItem td = new ToDoItem();
String inputline;
Scanner keyboard = new Scanner(System.in);
int i = 0;
String[] stringArray = new String[100];
private void setItems(ToDoItem[] items) throws FileNotFoundException {
File file = new File("ToDoItems.txt");
Scanner ReadFile = new Scanner(file);
while (ReadFile.hasNext()) {
String ListString = ReadFile.nextLine();
stringArray[100] = (ListString);
}
}
private ToDoItem[] getItems() {
return items;
}
public void addItem(int id, String description) {
stringArray[100] = (td.getId() + td.getDescription());
}
public String[] getAddItem() throws FileNotFoundException {
try (PrintWriter fout = new PrintWriter(new File("ToDoItems.txt"))) {
do {
System.out.println("add to the list? [y/n]");
inputline = keyboard.nextLine();
if ("y".equals(inputline)) {
i++;
stringArray[i] = (td.getId() + ". " + td.getDescription() + "\n");
fout.print(stringArray[i]);
} else {
System.out.println("Here is the list so far:");
}
} while ("y".equals(inputline));
return stringArray;
}
}
#Override
public String toString() {
return "ToDoList{" + "items=" + getItems()
+ '}';
}
I am supposed to use the "getAddItem" method to allow the user to add to the list. But I can't figure out how to add an array to an object. let alone make the object.

A little code to expand on what pininfarina said and to help you get going.
You need a ToDoItem class. Something like this:
public class ToDoItem {
private String id;
private String description;
public ToDoItem(String id, String description) {
this.id = id;
this.description = description;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
Then you need a ToDoList class to hold each item. You backed yours with an Array, but I used an ArrayList:
public class ToDoList {
private ArrayList<ToDoItem> items = new ArrayList<ToDoItem>();
public ToDoList(String fileName) throws FileNotFoundException {
File file = new File(fileName);
Scanner scanner = new Scanner(file);
try {
while (scanner.hasNext()) {
String nextLine = scanner.nextLine();
StringTokenizer tokenizer = new StringTokenizer(nextLine, ",");
String id = tokenizer.nextToken();
String description = tokenizer.nextToken();
items.add(new ToDoItem(id, description));
}
} finally {
scanner.close();
}
}
public void setItems(ArrayList<ToDoItem> newItems) {
this.items.addAll(newItems);
}
public List<ToDoItem> getItems() {
return items;
}
public void addItem(ToDoItem item) {
items.add(item);
}
#Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("ToDoList{");
for (ToDoItem item : items) {
builder.append(item.getId() + "," + item.getDescription() + "\n");
}
builder.append("}");
return builder.toString();
}
}
This includes a constructor that reads the file and parses out items. Each line in the file must be something like "1,something" because the tokenizer uses the comma. Note that the Scanner actually destroys the file as it reads it. You might consider using some sort of FileReader instead.
Finally you need a main class to run it. Something like this:
public class RunIt {
private static Scanner keyboard = new Scanner(System.in);
public static void main(String[] args) throws FileNotFoundException {
ToDoList list = new ToDoList("ToDoItems.txt");
try (PrintWriter fout = new PrintWriter(new File("ToDoItems.txt"))) {
String inputLine;
do {
System.out.println("add to the list? [y/n]");
inputLine = keyboard.nextLine();
if ("y".equals(inputLine)) {
System.out.println("enter a to-do using the format 'id,description'");
StringTokenizer tokenizer = new StringTokenizer(keyboard.nextLine(),
",");
String id = tokenizer.nextToken();
String description = tokenizer.nextToken();
list.addItem(new ToDoItem(id, description));
} else {
System.out.println("Here is the list so far:");
System.out.println(list);
}
} while ("y".equals(inputLine));
}
}
}
Please note that there is a lot of room for improvement here (exception handling, more robust file reading, etc), but this should get you started.

You are asking a broad question. Here's some design tips for you.
Create your collection class. This could be named ToDoList. Then create the attributes and behaviors of this class. One attribute will be the collection variable of your to do list items. You can use, List, ArrayList, etc. Behaviors could be add, remove, reorder, and etc.
Create your item class. Again with the attributes and behaviors. Attributes could include what to do, date, importance level, etc.
When you read your file, have your program to instantiate your ToDoItem class for every line, item etc. then save them into the previously created container class which is your ToDoList.
You can use your ToDoList class' addItem method (behavior) to have your users add more items into your ToDoList. If you want to keep the list even after your program closes. You can create a database to store your objects.
Good luck.

How do I store information from methods to be used in another session?

So I'm making a program that will store the meetings I've had with some kids I'm tutoring. It'll keep tabs on the meeting times, discussions, and how many hours I've done. I know how to write all the methods to do that, but my issue is that the program will only hold that information for the session that the program is open... how would I go about storing this information and accessing it after the program is closed and opened again?
This is some excerpts from a test score keeper program I did in java class that has this same issue...
public class Student {
private String name;
private int test1;
private int test2;
private int test3;
public Student() {
name = "";
test1 = 0;
test2 = 0;
test3 = 0;
}
public Student(String nm, int t1, int t2, int t3){
name = nm;
test1 = t1;
test2 = t2;
test3 = t3;
}
public Student(Student s){
name = s.name;
test1 = s.test1;
test2 = s.test2;
test3 = s.test3;
}
public void setName(String nm){
name = nm;
}
public String getName (){
return name;
}
public void setScore (int i, int score){
if (i == 1) test1 = score;
else if (i == 2) test2 = score;
else test3 = score;
}
public int getScore (int i){
if (i == 1) return test1;
else if (i == 2) return test2;
else return test3;
}
public int getAverage(){
int average;
average = (int) Math.round((test1 + test2 + test3) / 3.0);
return average;
}
public int getHighScore(){
int highScore;
highScore = test1;
if (test2 > highScore) highScore = test2;
if (test3 > highScore) highScore = test3;
return highScore;
}
public String toString(){
String str;
str = "Name: " + name + "\n" + //\n makes a newline
"Test 1: " + test1 + "\n" +
"Test 2: " + test2 + "\n" +
"Test 3: " + test3 + "\n" +
"Average: " + getAverage();
return str;
}
}

If your data is not too big or complicated - something that you could save in a Rolodex in days gone by - you can save it to a file. Add methods to your class that will format the data properly and write it to a given OutputStream or Writer or whatever. And a method that will read it back.
To write to the file, add an option "save" in your program menu, and when it's chosen, open a file, iterate through your data, and call the saving method for each of your object.
To read from the file, add an option "load" in your program menu, and when it's chosen, open a file, and use your method of reading for each object.
The method for reading can be a static method in the class, that will first see if there are any data in the file and if it can read them properly, and only if it did, will create an object and return it (otherwise return null). There are other options, but this is the one that most encapsulates the needs of the object.
There is also an option to serialize and deserialize each object and put it in an object stream.
If the data is complicated, and there are many objects with various relations between them, you should use a database. This will require learning some database design and SQL.
To demonstrate the file reading/writing idea, add to your Student class:
public void save(PrintWriter outfile) {
outfile.format("%s|%d|%d|%d%n", name, test1, test2, test3);
}
This will write a line with the fields separated by "|" (vertical bar). Of course, you'll have to make sure none of the student names has a vertical bar in it. So you'll need to modify your 4-parameter constructor and your setter:
public Student(String nm, int t1, int t2, int t3) {
name = nm.replaceAll("\\|", "");
test1 = t1;
test2 = t2;
test3 = t3;
}
public void setName(String nm) {
name = nm.replaceAll("\\|", "");
}
Now, to read the file, we add a static method:
public static Student load(BufferedReader infile) throws IOException {
String line;
line = infile.readLine();
// Check if we reached end of file
if (line == null) {
return null;
}
// Split the fields by the "|", and check that we have no less than 4
// fields.
String[] fields = line.split("\\|");
if (fields.length < 4) {
return null;
}
// Parse the test scores
int[] tests = new int[3];
for (int i = 0; i < 3; i++) {
try {
tests[i] = Integer.parseInt(fields[i + 1]);
} catch (NumberFormatException e) {
// The field is not a number. Return null as we cannot parse
// this line.
return null;
}
}
// All checks done, data ready, create a new student record and return
// it
return new Student(fields[0], tests[0], tests[1], tests[2]);
}
You can see that this is more complicated, because you need to check that everything is OK at every step. In any case when things are not OK, we return null but of course, you can decide to just display a warning and read the next line. You'll have to return null when there are no more lines, though.
So, assuming we have a List<Student> students, here is how we write it to a file. I just chose "students.txt" but you can specify a full path leading where you want it. Note how I'm making a backup of the old file before I open the new file. If something goes wrong, at least you have the previous version of the file.
File f = new File("students.txt");
if (f.exists()) {
File backup = new File("students.bak");
if ( ! f.renameTo(backup) ) {
System.err.println( "Could not create backup.");
return;
}
f = new File("students.txt");
}
try ( PrintWriter outFile = new PrintWriter(f);) {
for (Student student : students) {
student.save(outFile);
}
} catch (FileNotFoundException e) {
System.err.println("Could not open file for writing.");
return;
}
After you do this, if you look for the file "students.txt", you will see the records you wrote in it.
How about reading it? Assume we have an empty students list (not null!):
try ( BufferedReader inFile = new BufferedReader(new FileReader(f))) {
Student student;
while ( ( student = Student.load(inFile)) != null) {
students.add(student);
}
} catch (FileNotFoundException e) {
System.err.println( "Could not open file for reading.");
return;
} catch (IOException e) {
System.err.println( "An error occured while reading from the file.");
}
Having done this, you can check your students list, and unless there were errors in the file, all your records will be there.
This is a demonstration, of course. You may want to read into some other collection or instead of printing an error and returning do something else. But it should give you the idea.

You could use db4o for persisting your data. Its an object-database with a spimple api to use. You can store java object read or delete them..
Download it here DB4O
And use the snippets of this tutorial (GER):Tutorial in German
Here is an example:
and Code:
package db4o.example;
public class Student {
String name;
public Student(String name) {
this.name = name;
}
#Override
public String toString() {
return "Student Name: " + name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
package db4o.example;
import java.util.List;
import com.db4o.Db4oEmbedded;
import com.db4o.ObjectContainer;
public class Main {
public static void main(String[] args) {
ObjectContainer db = Db4oEmbedded.openFile("F:\\studentDB");
saveExample(db);
readAllExample(db);
readExample(db);
deleteAllExample(db);
db.close();
}
private static void deleteAllExample(ObjectContainer db) {
System.out.println("DeleteAllExample Example:");
List<Student> allStudents =readAllExample(db);
for (Student student : allStudents) {
db.delete(student);
}
db.commit();
}
private static List<Student> readAllExample(ObjectContainer db) {
System.out.println("ReadAllExample Example:");
List<Student> allStudents = db.query(Student.class);
System.out.println("Count: " + allStudents.size());
for (Student student : allStudents) {
System.out.println(student);
}
return allStudents;
}
private static void readExample(ObjectContainer db) {
System.out.println("ReadExample Example:");
Student queryStudent = new Student("Max Mustermann");
// Gets all Students named Max Mustermann
List<Student> students = db.queryByExample(queryStudent);
System.out.println("Count: " + students.size());
for (Student student : students) {
System.out.println(student);
}
}
private static void saveExample(ObjectContainer db) {
System.out.println("Save Example:");
Student myStudent = new Student("Max Mustermann");
db.store(myStudent);
db.commit();
}
}

Splitting skips half a content when splitting by #

I have an android application that requests data from a text file. when I try to separate the data and initialize classes, I have serious trouble because half the data after splitting is missing. The code for the DataSource is:
indicators = new ArrayList<Indicator>();
try {
InputStream fileStream = getResources().openRawResource(
R.raw.indicators);
int fileLen = fileStream.available();
// Read the entire resource into a local byte buffer.
byte[] fileBuffer = new byte[fileLen];
fileStream.read(fileBuffer);
fileStream.close();
displayText = new String(fileBuffer);
String[] counts = displayText.split("#");
for(String i: counts) {
String[] temps = i.split(";");
indicators.add(new Indicator(temps[0],temps[1],temps[2]));
}
} catch (IOException e) {
// exception handling
}
for(Indicator i: indicators) Log.v("indicator", i.toString());
and the code for the Indicator class can be found here:
public class Indicator {
private String name;
private String isoCode;
private String topic;
public Indicator(String topic, String isoCode,String name) {
this.name = name;
this.isoCode = isoCode;
this.topic = topic;
}
public String getName() {
return this.name;
}
public String getIsoCode() {
return this.isoCode;
}
public String getTopic() {
return this.topic;
}
public String toString() {
return (this.topic + "," + this.isoCode + "," + this.name);
}
}
After doing this process the following log file comes up with a lot of content missing:
http://pastebin.com/1j5s1Z81
The file seems to be skipping every other entry and because of that, my entire software is messing up. The source file below is:
http://pastebin.com/eAzppMdb

I have not been able to solve the issue by ammending the command. I found a way around this problem however by using the BufferedReader class that read the opened string in. This has seemed to solve the issue.