The signature of the FileInputStream constructor is:<\/strong><\/p>\npublic FileInputStream(File file) throws FileNotFoundException \r\n<\/pre>\nThis constructor takes a file as an argument. It throws FileNotFoundException if the file does not exist or if the file is a directory.<\/p>\n
Code to understand the FileInputStream class:<\/strong><\/p>\npackage com.DataFlair.FileOpening;\r\nimport java.io.*; \r\nimport java.util.Scanner; \r\npublic class FileInputStreamClass\r\n{\r\n public static void main(String args[]) \r\n { \r\n try \r\n { \r\n File file_create=new File(\"G:\\\\Internship\\\\NewTextFile.txt\"); \r\n FileInputStream fin=new FileInputStream(file_create);\r\n System.out.println(\"The content of the File are: \"); \r\n int ch=0; \r\n while((ch=fin.read())!=-1) \r\n { \r\n System.out.print((char)ch); \r\n } \r\n } \r\n catch(Exception e) \r\n { \r\n e.printStackTrace(); \r\n } \r\n } \r\n}\r\n<\/pre>\nThe output of the above code:<\/strong><\/p>\nThe content of the File are:
\nThis is a tutorial on how to open a file in Java
\nDataFlair<\/div>\n
Open the file using the Java BufferedReader class<\/h3>\n
The Java BufferedReader class reads characters from the character input stream. It is part of the java.io package. We can use the constructor of this class to open and read a file.<\/p>\n
When we open a file using the Java BufferedReader class, then the information of the file is displayed line by line instead of displaying each character. It increases the readability of the file . There is no explicit code required in the program to close the file it implicitly closes after processing is done. Java BufferedReader class is suitable to use when the files contain large amounts of information.<\/p>\n
The signature of the constructor is:<\/strong><\/p>\npublic BufferedReader(Reader in) \r\n<\/pre>\nThe constructor throws the FileNotFoundException, if the file does not exist or is the name of a directory.<\/p>\n
Code to understand the BufferedReader class:<\/strong><\/p>\npackage com.DataFlair.FileOpening;\r\nimport java.io.*; \r\nimport java.util.Scanner; \r\npublic class BufferedReaderClass\r\n{\r\n public static void main(String args[]) \r\n { \r\n try \r\n { \r\n File file_open=new File(\"G:\\\\Internship\\\\NewTextFile.txt\"); \r\n BufferedReader br=new BufferedReader(new FileReader(file_open)); \r\n System.out.println(\"The content of the file are: \"); \r\n int ch=0; \r\n while((ch=br.read())!=-1) \r\n { \r\n System.out.print((char)ch); \r\n } \r\n } \r\n catch(Exception e) \r\n { \r\n e.printStackTrace(); \r\n } \r\n } \r\n}\r\n<\/pre>\nThe output of the above code is:<\/strong><\/p>\nThe content of the file are:
\nThis is a tutorial on how to open a file in Java
\nDataFlair<\/div>\n
Open the file using the Java FileReader class<\/h3>\n
The Java FileReader class is also a part of the java.io package, and we can use it to read and open files as well. Using this class, we can read the raw bytes of a file. We use the constructor of the FileReader class to open and read a file.<\/p>\n
When we open a file using the Java BufferedReader class, the information of the file is displayed line by line instead of displaying each character. It increases the readability of the file. There is no explicit code required in the program to close the file; it implicitly closes after processing is done. Java BufferedReader class is suitable for use when the files contain large amounts of information.<\/p>\n
The signature of the constructor is:<\/strong><\/p>\npublic FileReader(File file) throws FileNotFoundException \r\n<\/pre>\nThe constructor throws the FileNotFoundException, if the file does not exist or is the name of a directory.<\/p>\n
Code to understand the FileReader class:<\/strong><\/p>\npackage com.DataFlair.FileOpening;\r\nimport java.io.*;\r\npublic class FileReaderClass\r\n{\r\n public static void main(String args[]) \r\n { \r\n try \r\n { \r\n FileReader file_open=new FileReader(\"G:\\\\Internship\\\\NewTextFile.txt\"); \r\n System.out.println(\"The contents of the file are: \"); \r\n int ch=0; \r\n while((ch=file_open.read())!=-1) \r\n { \r\n System.out.print((char)ch); \r\n } \r\n } \r\n catch(Exception e) \r\n { \r\n e.printStackTrace(); \r\n } \r\n } \r\n}\r\n<\/pre>\nThe output of the above code:<\/strong><\/p>\nThe contents of the file are:
\nThis is a tutorial on how to open a file in Java
\nDataFlair<\/div>\n
Open a file using the Java Scanner class<\/h3>\n
The Java Scanner class is part of the Java utility package(java.util). It is also used to open and read files. The constructor of the scanner class takes the file as input and reads the file. If the file does not exist or if it is the name of a directory, the constructor throws the FileNotFoundException.<\/p>\n
The signature of the constructor is:<\/strong><\/p>\npublic scanner (File source) throws FileNotFoundException \r\n<\/pre>\nCode to understand the Scanner class:<\/strong><\/p>\npackage com.DataFlair.FileOpening;\r\nimport java.io.File;\r\nimport java.util.*;\r\npublic class ScannerClass\r\n{\r\n public static void main(String[] args) \r\n { \r\n try \r\n { \r\n File file_open=new File(\"G:\\\\Internship\\\\NewTextFile.txt\"); \r\n Scanner sc = new Scanner(file_open); \r\n System.out.println(\"The contents of the file are: \");\r\n while (sc.hasNextLine()) \r\n System.out.println(sc.nextLine()); \r\n } \r\n catch(Exception e) \r\n { \r\n e.printStackTrace(); \r\n } \r\n } \r\n}\r\n<\/pre>\nThe output of the above code:<\/strong><\/p>\nThe contents of the file are:
\nThis is a tutorial on how to open a file in Java
\nDataFlair<\/div>\n
Code to open a file using the Scanner class but without any loop:<\/strong><\/p>\npackage com.DataFlair.FileOpening;\r\nimport java.io.File;\r\nimport java.io.FileNotFoundException;\r\nimport java.util.Scanner;\r\npublic class ReadingEntireFileWithoutLoop\r\n{\r\n public static void main(String[] args)throws FileNotFoundException\r\n {\r\n File file = new File(\"G:\\\\Internship\\\\NewTextFile.txt\");\r\n Scanner sc = new Scanner(file);\r\n sc.useDelimiter(\"\\\\A\");\/\/Using a custom character as a delimeter,in this case \"\\\\A\"\r\n System.out.println(sc.next());\r\n }\r\n}\r\n<\/pre>\nThe output of the above code:<\/strong><\/p>\nThis is a tutorial on how to open a file in Java
\nDataFlair<\/div>\n
Open file using the NIO package<\/h3>\n
The java.nio package contains a method readAllLines(), which reads all lines from a file and bytes from the file are decoded into characters using the UTF-8 charset. The method returns all the lines of the file as a list.<\/p>\n
The signature of the method is:<\/strong><\/p>\npublic static List<String> readAllLines(Path path) throws IOException<\/pre>\nWhere path is the path of the File.<\/p>\n
The above method can also be written in a simpler way as:<\/p>\n
File.readAllLines(path, Standard CharSets.UTF_8) \r\n<\/pre>\nWe will also need an empty list to store the data.<\/p>\n
Collection.emptyList()<\/strong> is a method of the Collection class of java.util package. The method is used to obtain an empty list.<\/p>\nThe signature of the method is:<\/strong><\/p>\npublic static final <T> List <T> emptyList() \r\n<\/pre>\nCode to understand the nio package and opening file in a List:<\/strong><\/p>\npackage com.DataFlair.FileOpening;\r\nimport java.util.*; \r\nimport java.nio.charset.StandardCharsets; \r\nimport java.nio.file.*; \r\nimport java.io.*; \r\npublic class nioPackage\r\n{\r\n public static List<String> readFileInList(String file_Name) \r\n { \r\n List<String> lines = Collections.emptyList(); \r\n try \r\n { \r\n lines=Files.readAllLines(Paths.get(file_Name), StandardCharsets.UTF_8); \r\n } \r\n catch (IOException e) \r\n { \r\n e.printStackTrace(); \r\n } \r\n return lines; \r\n } \r\n public static void main(String[] args) \r\n { \r\n List list = readFileInList(\"G:\\\\internship\\\\NewTextFile.txt\"); \r\n Iterator<String> iter = list.iterator(); \r\n System.out.println(\"The contents of the file are: \");\r\n while (iter.hasNext()) \r\n System.out.println(iter.next()); \r\n } \r\n} \r\n<\/pre>\nThe output of the above code:<\/strong><\/p>\nThe contents of the file are:
\nThis is a tutorial on how to open a file in Java
\nDataFlair<\/div>\n
Code to understand the nio package and open a file in a String:<\/strong><\/p>\npackage com.DataFlair.FileOpening;\r\nimport java.nio.file.*;\r\npublic class nioPackageString\r\n{\r\n public static String openFileAsString(String fName)throws Exception\r\n {\r\n String contents = \"\";\r\n contents = new String(Files.readAllBytes(Paths.get(fName)));\r\n return contents;\r\n }\r\n public static void main(String[] args) throws Exception\r\n {\r\n String data = openFileAsString(\"G:\/\/Internship\/\/NewTextFile.txt\");\r\n System.out.println(data);\r\n }\r\n}\r\n<\/pre>\nThe output of the above code:<\/strong><\/p>\nThis is a tutorial on how to open a file in Java
\nDataFlair<\/div>\n
Conclusion<\/h3>\n
As we can see, there are many ways to read\/open a file. It all depends on the programmer\u2019s will, which method suits his purpose. In this article, we saw all the different ways in which we can open a file. We discussed each of these methods with proper examples and code.<\/p>\n","protected":false},"excerpt":{"rendered":"
We already know how to create a file in Java. Java also provides us with the provision to open and access the contents of a file. There are a total of six different ways...<\/p>\n","protected":false},"author":5,"featured_media":108950,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[36736,36735,36739,36738,36740,36742,36741,26820,36737],"class_list":["post-101041","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java","tag-different-ways-to-open-a-file-in-java","tag-how-to-open-a-file-in-java","tag-open-a-file-using-bufferedreader-class-in-java","tag-open-a-file-using-fileinputstream-class-in-java","tag-open-a-file-using-filereader-class-in-java","tag-open-a-file-using-nio-package-in-java","tag-open-a-file-using-scanner-class-in-java","tag-open-file-in-java","tag-opening-file-using-java-desktop-class-in-java"],"yoast_head":"\n
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![\"desktop](\"https:\/\/data-flair.training\/blogs\/wp-content\/uploads\/sites\/2\/2022\/04\/desktop-method.webp\")
<\/a><\/p>\n