diff --git a/README.md b/README.md
index dcf6f124..eccbc22c 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,7 @@ This action allows you to work with Java and Scala projects.
 
 ## Usage
 
-  - `java-version`: _(required)_ The Java version to set up. Takes a whole or [semver](#supported-version-syntax) Java version.
+  - `java-version`: The Java version to set up. Takes a whole or [semver](#supported-version-syntax) Java version. If not specified, the action will expect `.java-version` file to be in the repository root. See [more details](docs/advanced-usage.md#Java-version-file) in about `.java-version` file. 
    
   - `distribution`: _(required)_ Java [distribution](#supported-distributions).
 
diff --git a/docs/advanced-usage.md b/docs/advanced-usage.md
index 6423d06c..88ecc0c4 100644
--- a/docs/advanced-usage.md
+++ b/docs/advanced-usage.md
@@ -16,6 +16,7 @@
 - [Publishing using Gradle](#Publishing-using-Gradle)
 - [Hosted Tool Cache](#Hosted-Tool-Cache)
 - [Modifying Maven Toolchains](#Modifying-Maven-Toolchains)
+- [Java-version file](#Java-version-file)
 
 See [action.yml](../action.yml) for more details on task inputs.
 
@@ -478,3 +479,20 @@ steps:
       something_else
       something_other
 ```
+
+## Java-version file
+If the `java-version` input is not specified, the action will look for a `.java-version` file at the root of the repository. If the file is found, action will try to install the most suitable version.
+Action is able to recognize all variants of the version description according to [jenv](https://github.com/jenv/jenv). 
+Valid entry options:
+```
+major versions: 8, 11, 16, 17
+more specific versions: 17.0, 11.0, 11.0.4, 8.0.232, 8.0.282+8
+early access (EA) versions: 15-ea, 15.0.0-ea, 15.0.0-ea.2, 15.0.0+2-ea
+versions with specified distribution: openjdk64-11.0.2
+```
+If the file contains multiple versions, only the first one will be recognized.
+If action was able to recognize a version in the file that matches the pattern, then attempts will begin to install the most appropriate version. The logic for installing the appropriate version:
+action will try to install the specified version. If this version is not available for a given distribution, action will try to install a less specific version according to the algorithm. Attempts will continue until a suitable version is installed or the attempt to install a version specifying only with major tag fails.
+Algorithm for selecting the appropriate version:
+If a particular patch specification was present in the version (for example, the early access postfix `-ea*` in `major.minor.patch-ea*` notation), action will try to install the version without it in the format `major.minor.patch`. Next, if the install fails again, action will try to install the `major.minor` version. On failure, action will try to install the `major` version and fail on failure.
+If the version was originally specified not in full format, then the process will be similar, but it will not start from the first step.
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