- Create A New File If Not Exists Java
- Java Create File If Not Exists Without
- Java Create File If Not Exists In Javascript
- File exists method in Java with examples. The exists function is a part of the File class in Java. This function determines whether the is a file or directory denoted by the abstract filename exists or not. The function returns true if the abstract file path exists or else returns false.
- The Java File class of the Java IO API enables you to do basic file system actions like renaming or deleting files, create, rename or delete directories, obtain directory listings etc.
1. Overview
In Java create file tutorial, we show howto create a file in Java. We create files with built-in classes including File, FileOutputStream, andFiles. We also use two third-party libraries: Apache.
In this tutorial, we're going to focus on the standard open options available for files in Java.
We'll explore the StandardOpenOption enum that implements the OpenOption interface and that defines these standard open options.
2. The OpenOption Parameter
In Java, we can work with files using the NIO2 API, which contains several utility methods. Some of these methods use an optional OpenOption parameter that configures how to open or create a file. In addition, this parameter will have a default value if not set, which can be different for each of these methods.
The StandardOpenOption enum type defines the standard options and implements the OpenOption interface.
Here's the list of supported options we can use with the StandardOpenOptions enum:
- WRITE: opens the file for write access
- APPEND: appends some data to the file
- TRUNCATE_EXISTING: truncates the file
- CREATE_NEW: creates a new file and throws an exception if the file already exists
- CREATE: opens the file if it exists or creates a new file if it does not
- DELETE_ON_CLOSE: deletes the file after closing the stream
- SPARSE: the newly created file will be sparse
- SYNC: preserves the content and the metadata of the file synchronized
- DSYNC: preserves only the content of the file synchronized
In the next sections, we'll see examples of how to use each of these options.
To avoid any confusion on the file path, let's get a handle on the home directory of the user, which will be valid across all operating systems:
3. Opening a File for Reading and Writing
First, if we want to create a new file if it does not exist we can use the option CREATE:
We can also use the option CREATE_NEW, which will create a new file if it does not exist.However, it will throw an exception if the file already exists.
Secondly, if we want to open the file for reading we can use the newInputStream(Path, OpenOption..) method. This method opens the file for reading and returns an input stream:
Notice how we didn't use the option READ because it's used by default by the method newInputStream. Windows 7 professional 32 bit product key crack free download.
Third, we can create a file, append to a file, or write to a file by using the newOutputStream(Path, OpenOption..) method. This method opens or creates a file for writing and returns an OutputStream.
The API will create a new file if we don't specify the open options, and the file does not exist. However, if the file exists, it will be truncated. This option is similar to calling the method with the CREATE and TRUNCATE_EXISTING options.
Let's open an existing file and append some data:
4. Creating a SPARSE File
We can tell the file system that the newly created file should be sparse (files containing empty spaces that will not be written to disk).
Create A New File If Not Exists Java
For this, we should use the option SPARSE with the CREATE_NEW option. However, this option will be ignored if the file system does not support sparse files. Outlook 2016 for mac counts wrong.
Let's create a sparse file:
5. Keeping the File Synchronized
The StandardOpenOptions enum has SYNC and DSYNC options. These options require that data is written to the file synchronously in the storage. In other words, these will guarantee that the data is not lost in the event of a system crash.
Let's append some data to our file and use the option SYNC:
The difference between SYNC and DSYNC is that SYNCstores the content and the metadata of the file synchronously in the storage, while DSYNC stores only the contents of the file synchronously Gran turismo 5 keygen.exe download. in the storage.
6. Deleting the File After Closing the Stream
The StandardOpenOptions enum also offers a useful option that gives us the ability to destroy the file after closing the stream. This useful if we want to create a temporary file.
Let's append some data to our file, and use the option DELETE_ON_CLOSE:
7. Conclusion
In this tutorial, we covered the available options to open files in Java using the new file system API (NIO2) that was shipped as a part of Java 7.
As usual, the source code with all the examples in the tutorial can be found over on Github.
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To check if a file, or a directory exists we can utilize
java.io.File.exists()
method. This method return either true
or false
. Before we can check whether its exists or not we need to create an instance of File
that represent an abstract path name of the file or directory. After we have the File
instance we can call the exists()
method to validate it.Java Create File If Not Exists In Javascript
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