Java: Store variables in file

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I know how to write text to a file and store it in Java, but I was wondering if there is a way of storing lots of variables that can be retrieved from the file at a later date, and put back into the Java application as variables.

I would be storing numbers and strings, but groups of them.

Thanks :)

Java can read properties files like it reads a map. This gives you an easy way of storing information using a key/value system.

Check out http://download.oracle.com/javase/6/docs/api/java/util/Properties.html

In Java How to Save and Load Data from a File, How do I write an object to a file and read it back? Java is pretty amazing with lots of API and with Java 8 we are fully enabled with lots more  Member variables: How objects store data. Local variables are useful, but because they provide only temporary storage, their value is limited. Since their lifetimes span the length of the method in which they are declared, local variables compare to a notepad that appears every time you receive a telephone call, but disappears when you hang up.

Use XML! You will make your variables portable. Even your coffee machine will be able to use them.

A SAX parser is built in Java.

Here is a Java snippet for writing an XML file:

public void saveToXML(String xml) {
    Document dom;
    Element e = null;
    // get an instance of factory
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try {
        // using a factory get an instance of document builder
        DocumentBuilder db = dbf.newDocumentBuilder();
        // create an instance of DOM
        dom = db.newDocument();
        // create the root element
        Element rootElement = dom.createElement("myparameters");
        // create data elements and place them under root
        e = dom.createElement("brightness");
        e.appendChild(dom.createTextNode(brightness));
        rootElement.appendChild(e);

Here is a Java snippet for reading an XML file:

public boolean loadFromXML(String xml) {    
    Document dom;
    // get an instance of the factory
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try {
        // using factory get an instance of the document builder
        DocumentBuilder db = dbf.newDocumentBuilder();
        // parse using builder to get DOM representation of the XML file
        dom = db.parse(xml);
        Element doc = dom.getDocumentElement();
        // get the data 
        brightness = getTextValue(brightness, doc, "brightness");
        contrast = getTextValue(contrast, doc, "contrast");

How to store data in Java objects, Developers use variables in Java to hold data, with all variables having a data type and a name. The data type determines the values that a variable can hold. In​  Java Exercises: Read a file line by line and store it into a variable. Last update on March 26 2019 11:44:42 (UTC/GMT +8 hours) Write a java program to read a file line by line and store it into a variable.

Wel the best way to do this is to make an XML file. It can store any object in any sort of collection.

I guess the XML is the best way to keep it and retrieve it later on.

java, If you want to store the value of your variable without converting it to a String then you shouldn't be using a Writer . You should be using a java.io. One variable in your program can store numeric data while another variable can store text data. Java has special keywords to signify what type of data each variable store. Use keywords like boolean, byte, char, int etc., when declaring your variables to set the data type of the variable.

How to assign file content into a variable in Java – Mkyong.com, In this example, you will use DataInputStreamto convert all the content into bytes, and create a String variable with the converted bytes. package  Java Variables. Variables are containers for storing data values. In Java, there are different types of variables, for example: String - stores text, such as "Hello". String values are surrounded by double quotes. int - stores integers (whole numbers), without decimals, such as 123 or -123.

Java exercises: Read a file line by line and store it into a variable , Java Input-Output: Exercise-13 with Solution. Write a java program to read a file line by line and store it into a variable. Sample Solution:. When you write a Java program that stores a value in a variable, you are using temporary storage; the value you store is lost when the program ends or the computer loses power. This type of storage is volatile. Permanent storage, on the other hand, is not lost when a computer loses power; it is nonvolatile.

Saving Objects in Java, An alternative to serialization is to customize a file format, however in some cases this customization results in multiple incompatible file types storing the same A Simple class to demonstrate Reflection in accessing instance variables. File I/O Operations. Java Annotations. Java Interview Questions. Java Interview Programs. Java Restful Web Services. Java 8 Features. Java Design Patterns. Search Algorithms. Sorting Algorithms. Data Structures. Gradle Configurations. #N#Program: How to store and read objects from a file? Sometimes we need to store the objects to the file

Comments
  • Ahh that is very useful! Thank you :)
  • You're welcome @Humpheh. I used this a while back to store a bunch of data and it really beats basic I/O
  • Haha well that's not really my main use for this, but thanks ;)
  • This is still a good answer, XML is universal. But the properties file in my case worked best for me.
  • +1 for coffee machine (read: Java machine) reading Java variables
  • But really, use JAXB for something like this instead of parsing the code manually. WAY more work to write and if you change your class you have to change your read/write code also. Completely unnecessary in such a case (because I hope we can assume that the variables have some connection and are already stored in a class/collection)