Java Video Tutorial 33
Here I continue covering everything about Java. Today I completely cover reading and writing Java Binary Streams.
I cover everything you need to know including DataOutputStream, FileOutputStream, BufferedOutputStream, all of the reading and writing primitive type methods and more.
All of the code follows the video. It is heavily commented.
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Code from the Video
import java.io.*;
// A binary stream is a series of data type values
// To read and write to them you use different methods
// based on the type of data that you are using
public class Lesson33{
public static void main(String[] args){
// Create an array of type Customer
Customer[] customers = getCustomers();
// A DataOutputStream allows you to print
// primitive data types to a file
DataOutputStream custOutput = createFile("/Users/derekbanas/Documents/workspace3/Java Code/src/customers.dat");
// Enhanced for loop for arrays
// Cycles through all of the people in the customers array
for(Customer person : customers){
createCustomers(person, custOutput);
}
// Closes the connection to the DataOutputStream
try {
custOutput.close();
} catch (IOException e) {
System.out.println("An I/O Error Occurred");
// Closes the program
System.exit(0);
}
getFileInfo();
}
// class that defines all the fields for my customers
private static class Customer{
public String custName;
public int custAge;
public double custDebt;
public boolean oweMoney;
public char custSex;
// constructor that's called when a customer is made
public Customer(String custName, int custAge, double custDebt, boolean oweMoney, char custSex){
this.custName = custName; // String
this.custAge = custAge; // Integer
this.custDebt = custDebt; // Double
this.oweMoney = oweMoney; // Boolean
this.custSex = custSex; // Character
}
}
// Creates an array of Customer Objects
private static Customer[] getCustomers(){
Customer[] customers = new Customer[5];
customers[0] = new Customer("John Smith", 21, 12.25, true, 'M');
customers[1] = new Customer("Sally Smith", 30, 2.25, true, 'F');
customers[2] = new Customer("Paul Ryan", 21, 0, false, 'M');
customers[3] = new Customer("Mark Jacobs", 21, 3.25, true, 'M');
customers[4] = new Customer("Steve Nash", 21, 5.25, true, 'M');
return customers;
}
// Create the file and the DataOutputStream that will write to the file
private static DataOutputStream createFile(String fileName){
try{
// Creates a File object that allows you to work with files
// on the hard drive. There is no difference between File
// for character or binary stream writing, or reading
File listOfNames = new File(fileName);
// FileOutputStream is used to write streams of data to a file
// You define whether a new file is created versus appended
// to based on if you add a boolean to the FileOutputStream
// FileOutputStream(file, true) : Appends to the file
// FileOutputStream(file, false) : Creates a new file
// BufferedOutputStream gathers all the data and then writes
// it all at one time (Speeds up the Program)
// DataOutputStream is used to write primitive data to the file
DataOutputStream infoToWrite = new DataOutputStream(
new BufferedOutputStream(
new FileOutputStream(listOfNames)));
return infoToWrite;
}
// You have to catch this when you call FileWriter
catch(IOException e){
System.out.println("An I/O Error Occurred");
// Closes the program
System.exit(0);
}
return null;
}
// Create a string with the customer info and write it to the file
private static void createCustomers(Customer customer, DataOutputStream custOutput){
try{
// Write primitive data to the file
// Writes a String in UTF format
custOutput.writeUTF(customer.custName);
// Writes an Integer
custOutput.writeInt(customer.custAge);
// Writes a Double
custOutput.writeDouble(customer.custDebt);
// Writes a Boolean
custOutput.writeBoolean(customer.oweMoney);
// Writes a Character
custOutput.writeChar(customer.custSex);
// You also have writeByte, writeFloat, writeLong
// and writeShort
}
catch(IOException e){
System.out.println("An I/O Error Occurred");
System.exit(0);
}
}
// Read info from the file and write it to the screen
private static void getFileInfo(){
System.out.println("Info Written to File\n");
// Open a new connection to the file
File listOfNames = new File("/Users/derekbanas/Documents/workspace3/Java Code/src/customers.dat");
boolean eof = false;
try {
// A DataInputStream object has the methods for reading the data
// The BufferedInputStream gathers the data in blocks
// FileInputStream gets data from the file
DataInputStream getInfo = new DataInputStream(
new BufferedInputStream(
new FileInputStream(listOfNames)));
// Using a while loop that pulls data until EOFException is thrown
while (!eof){
// You have to read data in the exact order it was put in the file
String custName = getInfo.readUTF();
int custAge = getInfo.readInt();
double custDebt = getInfo.readDouble();
boolean oweMoney = getInfo.readBoolean();
char custSex = getInfo.readChar();
System.out.println(custName);
System.out.println(custAge);
System.out.println(custDebt);
System.out.println(oweMoney);
System.out.println(custSex + "\n");
}
} // END OF TRY
catch (EOFException e) {
eof = true;
}
// Can be thrown by FileInputStream
catch (FileNotFoundException e) {
System.out.println("Couldn't Find the File");
System.exit(0);
}
catch(IOException e){
System.out.println("An I/O Error Occurred");
System.exit(0);
}
}
}
nice as usual , thanks for sharing with us.
Thank you 🙂
sorry i pasted some wrong code in html, dont mind bro, i linked those tabs but im just unable to use jquery to slide those tabs.
im really sorry for avobe posts , my problem is solved now 😀 dont mind bro and my english isn’t good enough, but i hope u understand wht i say.:D
No problem. I’m glad you figured it out. I have a real bad allergy cold right now. That’s why I’ve been bad about answering questions
get well soon dear,, wish u all the best, take care
I’m better now. I’ll put up another tutorial tomorrow.
hey what about serialization(object input and object output stream), are you going to teach that also, because what if i want to transfer data over the network.?
Just found this series, nice and compact. Very well produced. Thanks for sharing.
You’re very welcome. I have many more coming 🙂
How did you add the arguments to the constructor properly after copying them without including the access modifiers.
And how did you initialize them inside the constructor,, you made the first two and the rest modified immediately..
what tricks you use…
Is there any reference to it..
is it eclipse tricks… I am using netbeans.
Thank you