Difference between getFreespace() and getUsableSpace of File

Question

I could not point out exact difference between getFreeSpace() and getUsableSpace() method of File class. When i run following code

Answer 1

The javadoc of getUsableSpace() says:

When possible, this method checks for write permissions and other operating system restrictions and will therefore usually provide a more accurate estimate of how much new data can actually be written than getFreeSpace().

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So we should choose getUsableSpace in most cases.

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update:

notice below reported bug, in a very large disk the size of the space may exceed the limits of long type and return a negative value:

JDK-8179320 : File getUsableSpace() returns a negative number on very large file system