Top Most How to append text into File in Java – FileWriter Example

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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Top Most How to read file line by line in Java - BufferedReader Scanner Example Tutorial

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 6^th 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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Top Most How to Convert InputStream to Byte Array in Java - 2 Examples

Sometimes we need to convert InputStream to byte array in Java, or you can say reading InputStream as byte array, In order to pass output to a method which accept byte array rather than InputStream. One popular example of this, I have seen is older version of Apache commons codec, while converting byte array to hex string. Though, later version of same library do provide an overloaded method, to accept InputStream. Java File API provides excellent support to read files like image, text as InputStream in Java program, but as I said, sometime you need  need String or byte array, instead of InputStream . Earlier we have seen 5 ways to convert InputStream to String in Java , we can use some of the techniques from there while getting byte array from InputStream in Java. If you like to use Apache commons library, which I think you should, there is a utility class called IOUtils, which can be used to easily convert InputStream to byte array in Java. If you don't like using open source library for such kind of thinks, and like to write your own method, you can easily do so by using standard Java File API. In this Java tutorial we will see examples of both ways to convert InputStream to byte array in Java.

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Top Most 5 ways to convert InputStream to String in Java

InputStream to String Conversion Example

Converting InputStream to String in Java has become very easy after introduction of Scanner class in Java 5 and due to development of several open source libraries like Apache commons IOUtils and Google Open source guava-libraries which provides excellent support to convert InputStream to String in Java program. we often need to convert InputStream to String  while working in Java for example if you are reading XML files from InputStream and later performing XSLT transformation on it or if InputStream is reading data from text file or text input Source and we either want to log  Strings in log file or want to operate on whole String. Before Java 5 you would have to write lots of boiler plate code to read String line by line or byte by byte depending upon whether you are using either BufferedReader or not but as I said since JDK 5 added Scanner for reading input, its fairly easy to convert InputStream into String.

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