Here, we create a bucket of bytes, which is used iteratively to copy data. In other words, during each iteration, bytes are read from the input stream and written on the output stream. The iteration finishes when no more bytes are left on the InputStream. The transferTo method was introduced in Java SE 9, and provides abstraction over the logic that we have seen above.
Java introduced this option in Java SE 7. In this tutorial we covered a different ways of writing InputStream content to a File. We wrote a different examples of using Apache Commons IO, guava. Also, we covered a couple of Core Java methods to achieve the same. This method copies the contents of the source file to a file in the specified destination directory creating a new file in the destination with the same name as the source.
It creates the destination directory and all the parent directories if they do not exist. If the destination file exists, it overwrites it. Like the copyFile method, it tries to preserve the last modified time. This will create a new file named sample-file. If they do not exist, it will create the all the folders. Similar to the copyFile , there is an overloaded method where we can pass a flag to preserve the last modified date but not guaranteed to succeed.
The difference between copyFile and copyFileToDirectory is copyFile allows us to specify the target file name which can be different from the source whereas we use copyFileToDirectory when we want to create a file in the destination with the same name as the source.
Hence if the source and destination directory are the same, it will throw a IOException. The moveFileToDirectory moves a file into the specified directory. Hence, the moved file will have the same name as the source file being moved. It accepts a boolean called createDestDir which if set to true will create the destination directory including all parent directories.
If we set createDestDir to false and if the target directory does not exist, it throws a java. If a file with the same name is already present in the destination, the move will fail with an org. The Apache Commons FileUtils class has two methods with which we can check if a file is newer or older, comparing it to a date or another file or a time represented in milliseconds.
The above code checks if the file file1 is newer than May 1, If yes, it will print true else it will print false. This is the inverse of isFileNewer method. The deleteQuietly method deletes a file but never throws any exception. It returns true if the file deletion was successful. If the file does not exist, it returns false but throws no exceptions. The forceDelete method deletes a file but throws exception when the file could not be deleted. This post covered the Apache Commons FileUtils files operations or files manipulation.
We learnt how to read a file, write data to a file. It notified for both the new file creation and the directory change as a result of that. Now, as a result of the directory deletion all contents of that directory would be deleted. Since we had a file inside that, we get.
A FileFilter is a filter like a predicate for files. It is a FunctionalInterface with the below shown signature. It takes a File instance and returns a boolean. Why am I suddenly talking about FileFilter? We can use this with the file alteration observer. Similarly, the fileFileFilter checks if a file is a file and not a directory. The suffixFileFilter returns a filter which checks if the file name ends with the passed suffix string.
And the prefixFileFilter checks if the name starts with the passed prefix string. The FileFilterUtils class has methods and, or and not which allows us to combine FileFilters or to negate them. Finally, using notFileFilter , we can negate the check made by the file filter. Let us now see the other overloaded constructors present in the FileAlterationObserver class. For each of the variations discussed here, it would have another similar overload where we can pass the root directory as a File not a String.
First variation, we can pass a FileFilter. Then, only the files and directories which pass the FileFilter predicate check are eligible to be notified. We have a FileFilter which allows only directories and. We pass this as the second argument to the FileAlterationObserver constructor. The rest of the code is same and hence skipped. Now, as before, the thread will call the checkAndNotify once every three seconds.
But this time, the observer only considers directories and files ending with. It is an enum which allows us to control how the file name checks are to be performed.
It has three values:. Since the FileAlterationObserver has a addListener method we can add listeners dynamically.
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