Tampilkan postingan dengan label java IO tutorial. Tampilkan semua postingan
Tampilkan postingan dengan label java IO tutorial. Tampilkan semua postingan

Sabtu, 22 Oktober 2016

Sometimes before processing a file, you want to check it's last modified date to avoid processing an old file. Though some programmers prefer to attach date in the file name itself, I don't find it a cleaner approach. For example, suppose you are downloading closing prices of stocks and processing at the start of the day and loading into the database. In order to accidently process an old file, you can check the last modified date before processing and if it's in the acceptable range, you can process the file. You can get the last modified date of a file in Java by using java.io.File class. This is a class which represents both file and directory in Java. It contains a method called lastModified() which returns the last modified date of the file. This method returns a long millisecond epoch value, which you can convert to more readable dd MM yyyy HH:mm:sss format by using the SimpleDateFormat class of JDK. In this article, I'll tell you how to get the last modified date of file and directory in Java.
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Minggu, 24 Juli 2016

As I told you before that there are multiple ways to read a file in Java e.g. FileReader, BufferedReader, and FileInputStream. You chose the Reader or InputStream depending upon whether you are reading text data or binary data, for example, the BufferedReader class is mostly used to read a text file in Java. The Scanner class is also another way to read a text file in java. Even though Scanner is more popular as a utility to read user input from the command prompt, you will be glad to know that you can also read a file using Scanner. Similar to BufferedReader, it provides buffering but with a smaller buffer size of 1KB and you can also use the Scanner to read a file line by line in Java. Similar to readLine(), Scanner class also have nextLine() method which return the next line of the file. Scanner also provides parsing functionality e.g. you can not only read text but parse it into correct data type e.g. nextInt() can read integer and nextFloat() can read float and so on.
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Selasa, 05 Juli 2016

The Java IO API provides two kinds of interfaces for reading files, streams and readers. The streams are used to read binary data and readers to read character data. Since a text file is full of characters, you should be using a Reader implementations to read it. There are several ways to read a plain text file in Java e.g. you can use FileReader, BufferedReader or Scanner to read a text file. Every utility provides something special e.g. BufferedReader provides buffering of data for fast reading, and Scanner provides parsing ability. You can also use both BufferedReader and Scanner to read a text file line by line in Java. Then Java SE 8 introduces another Stream class java.util.stream.Stream which provides a lazy and more efficient way to read a file.
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Minggu, 30 Desember 2012

Some times we need to append text into File in Java instead of creating new File. Thankfully Java File API is very rich and it provides several ways to append text into File in Java. Previously we have seen how to create file and directory in Java and how to read and write to text file in Java and in this Java IO tutorial we will see how to append text into file in Java. We are going to use standard FileWriter and BufferedWriter approach to append text to File. One of the key point to remember while using FileWriter in Java is to initialize FileWriter to append text i.e. writing bytes at the end of File rather than writing on beginning of the File. In next section we will see complete Java program to append text into File in Java. By the way you can also use FileOutputStream instead of FileWriter if you would like to write bytes, instead of text. Similar to FileWriter, FileOutputStream constructoralso takes a boolean append argument to open connection to append bytes into File in Java.
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Senin, 23 Juli 2012

Line by Line reading in Java using BufferedReader and Scanner
There are multiple ways to read file line by line in Java. Most simple example of reading file line by line is using BufferedReader which provides method readLine() for reading file. Apart from generics, enum and varargs Java 1.5 has also introduced several new class in Java API one of the utility class is Scanner, which can also be used to read any file line by line in Java. Though BufferedReader is available in Java from JDK 1.1, java.util.Scanner provides more utility methods compared to BufferedReader. Scanner has method like hasNextLine() and nextLine() to facilitate line by line reading of file's contents. nextLine() returns String similar to readLine() but scanner has more utility methods like nextInt(), nextLong() which can be used to directly read numbers from file instead of converting String to Integer or other Number classes. By the way Scanner is rather new approach for reading file and BufferedReader is the standard one. This is my 6th tutorial on Java IO, In last couple of post we have seen creating file and directory in Java, parsing XML files using DOM and how to read properties file in Java. In this post we will focus on reading file line by line in Java using both BufferedReader and Scanner.
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