Java Programming: Lesson 47 - File I/O смотреть онлайн

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In the previous lesson (https://youtu.be/b_SoAmTfAaQ), we took a look at the do-while loop, a 4th option for iterating through a list or array. In this lesson, we learn how to create, write to, and read from files.

import java.util.File;
import java.util.FileWriter;
import java.util.IOException;
import java.util.FileNotFoundException;

String fileName = "helloWorld.txt";

try
{
File f = new File( fileName );
boolean b = f.createNewFile( );
}
catch( IOException e )
{
System.out.println( "File-create error" );
}

try
{
FileWriter w = new FileWriter( fileName );
w.write( "Hello, virtual world!" );
w.write( "It's a great day for programming" );
}
catch( IOException x )
{
System.out.println( "File-write error" );
}

try
{
File g = new File( fileName );
Scanner h = new Scanner( g );
while( g.hasNextLine( ) )
{
System.out.println( g.nextLine( ) );
}
}
catch( FileNotFoundException z )
{
System.out.println( "File wasn't found..." );
}

This code prints

Hello, virtual world!
It is a great day for programming!

to the console, after having created a file called helloWorld.txt and writing those lines to it

1:10 Review of System.out.printf
3:39 Review of do-while loop
4:00 NEW: Intro to File I/O
6:01 NEW: Importing Essential Classes for File I/O
8:11 NEW: Creating a File
12:08 NEW: Writing to a File
17:13 NEW: Reading a File

An equivalent lesson in Python is available here: https://youtu.be/E5ReF5fYJEk

Ready for threading? The Java continues here... https://youtu.be/LVeZ-kOyB1o

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