docs: added pom.xml and build.gradle

.github/workflows/e2e-versions.yml

@@ -469,7 +469,6 @@ jobs:
       - name: Verify Java
         run: bash __tests__/verify-java.sh "8" "${{ steps.setup-java.outputs.path }}"
         shell: bash
-
   setup-java-version-from-pom-maven-compiler-plugin-configuration:
     name: ${{ matrix.distribution }} version from pom.xml - ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
@@ -513,3 +512,86 @@ jobs:
       - name: Verify Java
         run: bash __tests__/verify-java.sh "8" "${{ steps.setup-java.outputs.path }}"
         shell: bash
+  setup-java-version-from-build-gradle-java-library-plugin-specification:
+    name: ${{ matrix.distribution }} version from build.gradle - ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [macos-latest, windows-latest, ubuntu-latest]
+        distribution: ['adopt', 'zulu', 'liberica']
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Create build.gradle file
+        shell: bash
+        run: |
+          echo "java {" > build.gradle
+          echo "    toolchain {" >> build.gradle
+          echo "        languageVersion.set(JavaLanguageVersion.of(11))" >> build.gradle
+          echo "    }" >> build.gradle
+          echo "}" >> build.gradle
+      - name: setup-java
+        uses: ./
+        id: setup-java
+        with:
+          distribution: ${{ matrix.distribution }}
+          java-version-file: 'build.gradle'
+      - name: Verify Java
+        run: bash __tests__/verify-java.sh "11" "${{ steps.setup-java.outputs.path }}"
+        shell: bash
+
+  setup-java-version-from-build-gradle-java-plugin-source-compatibility-specification:
+    name: ${{ matrix.distribution }} version from build.gradle - ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [macos-latest, windows-latest, ubuntu-latest]
+        distribution: ['adopt', 'zulu', 'liberica']
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Create pom.xml file
+        shell: bash
+        run: |
+          echo "java {" > build.gradle
+          echo "    sourceCompatibility = JavaVersion.VERSION_1_8" >> build.gradle
+          echo "    targetCompatibility = JavaVersion.VERSION_1_8" >> build.gradle
+          echo "}" >> build.gradle
+      - name: setup-java
+        uses: ./
+        id: setup-java
+        with:
+          distribution: ${{ matrix.distribution }}
+          java-version-file: 'build.gradle'
+      - name: Verify Java
+        run: bash __tests__/verify-java.sh "8" "${{ steps.setup-java.outputs.path }}"
+        shell: bash
+
+  setup-java-version-from-build-gradle-java-plugin-target-compatibility-specification:
+    name: ${{ matrix.distribution }} version from build.gradle - ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [macos-latest, windows-latest, ubuntu-latest]
+        distribution: ['adopt', 'zulu', 'liberica']
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Create pom.xml file
+        shell: bash
+        run: |
+          echo "java {" > build.gradle
+          echo "    targetCompatibility = JavaVersion.VERSION_21" >> build.gradle
+          echo "}" >> build.gradle
+      - name: setup-java
+        uses: ./
+        id: setup-java
+        with:
+          distribution: ${{ matrix.distribution }}
+          java-version-file: 'build.gradle'
+      - name: Verify Java
+        run: bash __tests__/verify-java.sh "21" "${{ steps.setup-java.outputs.path }}"
+        shell: bash

README.md

@@ -25,7 +25,7 @@ This action allows you to work with Java and Scala projects.
 
   - `java-version`: The Java version that is going to be set up. Takes a whole or [semver](#supported-version-syntax) Java version. If not specified, the action will expect `java-version-file` input to be specified.
 
-  - `java-version-file`: The path to the `.java-version` file. See more details in [about `.java-version` file](docs/advanced-usage.md#Java-version-file).
+  - `java-version-file`: The path to the `.java-version` or `pom.xml` or `build.gradle` file. See more details in [about `.java-version` file](docs/advanced-usage.md#Java-version-file).
    
   - `distribution`: _(required)_ Java [distribution](#supported-distributions).
 

dist/cleanup/index.js

@@ -103695,7 +103695,7 @@ var __importDefault = (this && this.__importDefault) || function (mod) {
     return (mod && mod.__esModule) ? mod : { "default": mod };
 };
 Object.defineProperty(exports, "__esModule", ({ value: true }));
-exports.getVersionFromFileContent = exports.isCacheFeatureAvailable = exports.isGhes = exports.isJobStatusSuccess = exports.getToolcachePath = exports.isVersionSatisfies = exports.getDownloadArchiveExtension = exports.extractJdkFile = exports.getVersionFromToolcachePath = exports.getBooleanInput = exports.getTempDir = void 0;
+exports.getVersionFromFile = exports.isCacheFeatureAvailable = exports.isGhes = exports.isJobStatusSuccess = exports.getToolcachePath = exports.isVersionSatisfies = exports.getDownloadArchiveExtension = exports.extractJdkFile = exports.getVersionFromToolcachePath = exports.getBooleanInput = exports.getTempDir = void 0;
 const os_1 = __importDefault(__nccwpck_require__(2037));
 const path_1 = __importDefault(__nccwpck_require__(1017));
 const fs = __importStar(__nccwpck_require__(7147));
@@ -103791,24 +103791,27 @@ function isCacheFeatureAvailable() {
     return false;
 }
 exports.isCacheFeatureAvailable = isCacheFeatureAvailable;
-function getVersionFromFileContent(fileName, content, distributionName) {
+function getVersionFromFile(fileName, content, distributionName) {
     var _a;
-    let fileContent = null;
+    let parsedVersion = null;
     core.debug(`Getting version from: '${fileName}'`);
     if (fileName.includes('.java-version')) {
-        fileContent = parseJavaVersionFile(content);
+        parsedVersion = parseJavaVersionFile(content);
     }
     else if (fileName.includes('pom.xml')) {
-        fileContent = parsePomXmlFile(content);
+        parsedVersion = parsePomXmlFile(content);
+    }
+    else if (fileName.includes('build.gradle')) {
+        parsedVersion = parseBuildGradleFile(content);
     }
     else {
         throw new Error(`File ${fileName} not supported, files supported: '.java-version' and 'pom.xml'`);
     }
-    if (!fileContent) {
+    if (!parsedVersion) {
         return null;
     }
-    core.debug(`Version from file '${fileContent}'`);
-    const tentativeVersion = avoidOldNotation(fileContent);
+    core.debug(`Version from file '${parsedVersion}'`);
+    const tentativeVersion = avoidOldNotation(parsedVersion);
     const rawVersion = tentativeVersion.split('-')[0];
     let version = semver.validRange(rawVersion) ? tentativeVersion : semver.coerce(tentativeVersion);
     core.debug(`Range version from file is '${version}'`);
@@ -103821,7 +103824,7 @@ function getVersionFromFileContent(fileName, content, distributionName) {
     }
     return version.toString();
 }
-exports.getVersionFromFileContent = getVersionFromFileContent;
+exports.getVersionFromFile = getVersionFromFile;
 function parseJavaVersionFile(content) {
     var _a, _b, _c, _d;
     const javaVersionRegExp = /(?<version>(?<=(^|\s|\-))(\d+\S*))(\s|$)/;
@@ -103849,11 +103852,8 @@ function parsePomXmlFile(xmlFileAsString) {
     return null;
 }
 function getByMavenProperties(xmlDoc) {
-    const possibleTagsRegex = [
-        'maven.compiler.source',
-        'maven.compiler.release',
-    ];
-    for (var tag of possibleTagsRegex) {
+    const versionTags = ['maven.compiler.source', 'maven.compiler.release'];
+    for (const tag of versionTags) {
         const version = getVersionByTagName(xmlDoc, tag);
         if (version !== null) {
             return version;
@@ -103878,29 +103878,32 @@ function getByMavenCompilerPluginConfig(xmlDoc) {
     var _a;
     const source = xmlDoc.find(n => {
         // Find <source> node
-        if (n.node.nodeName !== "source") {
+        if (n.node.nodeName !== 'source') {
             return false;
         }
         if (n.node.childNodes.length !== 1) {
             return false;
         }
         // Must be within <configuration>
-        if (n.up().node.nodeName !== "configuration") {
+        if (n.up().node.nodeName !== 'configuration') {
             return false;
         }
         // Which must be inside <plugin>
-        if (n.up().up().node.nodeName !== "plugin") {
+        if (n.up().up().node.nodeName !== 'plugin') {
             return false;
         }
         // Make sure the plugin is maven-compiler-plugin
-        const isCompilerPlugin = n.up().up().some(c => {
-            if (c.node.nodeName !== "artifactId") {
+        const isCompilerPlugin = n
+            .up()
+            .up()
+            .some(c => {
+            if (c.node.nodeName !== 'artifactId') {
                 return false;
             }
             if (c.node.childNodes.length !== 1) {
                 return false;
             }
-            return c.first().toString() === "maven-compiler-plugin";
+            return c.first().toString() === 'maven-compiler-plugin';
         }, false, true);
         if (!isCompilerPlugin) {
             return false;
@@ -103909,6 +103912,42 @@ function getByMavenCompilerPluginConfig(xmlDoc) {
     });
     return (_a = source === null || source === void 0 ? void 0 : source.first().toString()) !== null && _a !== void 0 ? _a : null;
 }
+function parseBuildGradleFile(buildGradle) {
+    const versionDefinitionTypes = [getByJavaLibraryPlugin, getByJavaPlugin];
+    for (const definitionType of versionDefinitionTypes) {
+        const version = definitionType(buildGradle);
+        if (version !== null) {
+            return version;
+        }
+    }
+    return null;
+}
+function getByJavaLibraryPlugin(buildGradle) {
+    return getVersionByRegex(buildGradle, 'JavaLanguageVersion.of((d+))');
+}
+function getByJavaPlugin(buildGradle) {
+    const possibleRegex = [
+        'sourceCompatibilitys?=s?JavaVersion.VERSION_(?:1_)?(d+)',
+        'targetCompatibilitys?=s?JavaVersion.VERSION_(?:1_)?(d+)'
+    ];
+    for (var regex of possibleRegex) {
+        const version = getVersionByRegex(buildGradle, regex);
+        if (version !== null) {
+            return version;
+        }
+    }
+    return null;
+}
+function getVersionByRegex(content, regex) {
+    const match = content.match(new RegExp(regex));
+    if (match) {
+        core.debug(`Found java version: '${match[1]}' using regex: '${regex}'`);
+        return match[1];
+    }
+    else {
+        return null;
+    }
+}
 // By convention, action expects version 8 in the format `8.*` instead of `1.8`
 function avoidOldNotation(content) {
     return content.startsWith('1.') ? content.substring(2) : content;

dist/setup/index.js

@@ -105104,7 +105104,7 @@ function run() {
                     .readFileSync(versionFile)
                     .toString()
                     .trim();
-                const version = util_1.getVersionFromFileContent(versionFile, content, distributionName);
+                const version = util_1.getVersionFromFile(versionFile, content, distributionName);
                 core.debug(`Parsed version from file '${version}'`);
                 if (!version) {
                     throw new Error(`No supported version was found in file ${versionFile}`);
@@ -105352,7 +105352,7 @@ var __importDefault = (this && this.__importDefault) || function (mod) {
     return (mod && mod.__esModule) ? mod : { "default": mod };
 };
 Object.defineProperty(exports, "__esModule", ({ value: true }));
-exports.getVersionFromFileContent = exports.isCacheFeatureAvailable = exports.isGhes = exports.isJobStatusSuccess = exports.getToolcachePath = exports.isVersionSatisfies = exports.getDownloadArchiveExtension = exports.extractJdkFile = exports.getVersionFromToolcachePath = exports.getBooleanInput = exports.getTempDir = void 0;
+exports.getVersionFromFile = exports.isCacheFeatureAvailable = exports.isGhes = exports.isJobStatusSuccess = exports.getToolcachePath = exports.isVersionSatisfies = exports.getDownloadArchiveExtension = exports.extractJdkFile = exports.getVersionFromToolcachePath = exports.getBooleanInput = exports.getTempDir = void 0;
 const os_1 = __importDefault(__nccwpck_require__(2037));
 const path_1 = __importDefault(__nccwpck_require__(1017));
 const fs = __importStar(__nccwpck_require__(7147));
@@ -105448,24 +105448,27 @@ function isCacheFeatureAvailable() {
     return false;
 }
 exports.isCacheFeatureAvailable = isCacheFeatureAvailable;
-function getVersionFromFileContent(fileName, content, distributionName) {
+function getVersionFromFile(fileName, content, distributionName) {
     var _a;
-    let fileContent = null;
+    let parsedVersion = null;
     core.debug(`Getting version from: '${fileName}'`);
     if (fileName.includes('.java-version')) {
-        fileContent = parseJavaVersionFile(content);
+        parsedVersion = parseJavaVersionFile(content);
     }
     else if (fileName.includes('pom.xml')) {
-        fileContent = parsePomXmlFile(content);
+        parsedVersion = parsePomXmlFile(content);
+    }
+    else if (fileName.includes('build.gradle')) {
+        parsedVersion = parseBuildGradleFile(content);
     }
     else {
         throw new Error(`File ${fileName} not supported, files supported: '.java-version' and 'pom.xml'`);
     }
-    if (!fileContent) {
+    if (!parsedVersion) {
         return null;
     }
-    core.debug(`Version from file '${fileContent}'`);
-    const tentativeVersion = avoidOldNotation(fileContent);
+    core.debug(`Version from file '${parsedVersion}'`);
+    const tentativeVersion = avoidOldNotation(parsedVersion);
     const rawVersion = tentativeVersion.split('-')[0];
     let version = semver.validRange(rawVersion) ? tentativeVersion : semver.coerce(tentativeVersion);
     core.debug(`Range version from file is '${version}'`);
@@ -105478,7 +105481,7 @@ function getVersionFromFileContent(fileName, content, distributionName) {
     }
     return version.toString();
 }
-exports.getVersionFromFileContent = getVersionFromFileContent;
+exports.getVersionFromFile = getVersionFromFile;
 function parseJavaVersionFile(content) {
     var _a, _b, _c, _d;
     const javaVersionRegExp = /(?<version>(?<=(^|\s|\-))(\d+\S*))(\s|$)/;
@@ -105506,11 +105509,8 @@ function parsePomXmlFile(xmlFileAsString) {
     return null;
 }
 function getByMavenProperties(xmlDoc) {
-    const possibleTagsRegex = [
-        'maven.compiler.source',
-        'maven.compiler.release',
-    ];
-    for (var tag of possibleTagsRegex) {
+    const versionTags = ['maven.compiler.source', 'maven.compiler.release'];
+    for (const tag of versionTags) {
         const version = getVersionByTagName(xmlDoc, tag);
         if (version !== null) {
             return version;
@@ -105535,29 +105535,32 @@ function getByMavenCompilerPluginConfig(xmlDoc) {
     var _a;
     const source = xmlDoc.find(n => {
         // Find <source> node
-        if (n.node.nodeName !== "source") {
+        if (n.node.nodeName !== 'source') {
             return false;
         }
         if (n.node.childNodes.length !== 1) {
             return false;
         }
         // Must be within <configuration>
-        if (n.up().node.nodeName !== "configuration") {
+        if (n.up().node.nodeName !== 'configuration') {
             return false;
         }
         // Which must be inside <plugin>
-        if (n.up().up().node.nodeName !== "plugin") {
+        if (n.up().up().node.nodeName !== 'plugin') {
             return false;
         }
         // Make sure the plugin is maven-compiler-plugin
-        const isCompilerPlugin = n.up().up().some(c => {
-            if (c.node.nodeName !== "artifactId") {
+        const isCompilerPlugin = n
+            .up()
+            .up()
+            .some(c => {
+            if (c.node.nodeName !== 'artifactId') {
                 return false;
             }
             if (c.node.childNodes.length !== 1) {
                 return false;
             }
-            return c.first().toString() === "maven-compiler-plugin";
+            return c.first().toString() === 'maven-compiler-plugin';
         }, false, true);
         if (!isCompilerPlugin) {
             return false;
@@ -105566,6 +105569,42 @@ function getByMavenCompilerPluginConfig(xmlDoc) {
     });
     return (_a = source === null || source === void 0 ? void 0 : source.first().toString()) !== null && _a !== void 0 ? _a : null;
 }
+function parseBuildGradleFile(buildGradle) {
+    const versionDefinitionTypes = [getByJavaLibraryPlugin, getByJavaPlugin];
+    for (const definitionType of versionDefinitionTypes) {
+        const version = definitionType(buildGradle);
+        if (version !== null) {
+            return version;
+        }
+    }
+    return null;
+}
+function getByJavaLibraryPlugin(buildGradle) {
+    return getVersionByRegex(buildGradle, 'JavaLanguageVersion.of((d+))');
+}
+function getByJavaPlugin(buildGradle) {
+    const possibleRegex = [
+        'sourceCompatibilitys?=s?JavaVersion.VERSION_(?:1_)?(d+)',
+        'targetCompatibilitys?=s?JavaVersion.VERSION_(?:1_)?(d+)'
+    ];
+    for (var regex of possibleRegex) {
+        const version = getVersionByRegex(buildGradle, regex);
+        if (version !== null) {
+            return version;
+        }
+    }
+    return null;
+}
+function getVersionByRegex(content, regex) {
+    const match = content.match(new RegExp(regex));
+    if (match) {
+        core.debug(`Found java version: '${match[1]}' using regex: '${regex}'`);
+        return match[1];
+    }
+    else {
+        return null;
+    }
+}
 // By convention, action expects version 8 in the format `8.*` instead of `1.8`
 function avoidOldNotation(content) {
     return content.startsWith('1.') ? content.substring(2) : content;

docs/advanced-usage.md

@@ -485,4 +485,8 @@ It is able to parse the following files as `java-version-file`:
   - Maven compiler plugin
     - Setting the [source](https://maven.apache.org/plugins/maven-compiler-plugin/examples/set-compiler-source-and-target.html).
     - Setting the [release](https://maven.apache.org/plugins/maven-compiler-plugin/examples/set-compiler-release.html).
-    - **Note:** Since we are using a RegExp to find the java version, it doesn't grab the values from the tags `source` or `release` on `maven-compiler-plugin`.
+- `build.gradle` 
+  - Java library plugin: uses what is defined by `JavaLanguageVersion` example: `JavaLanguageVersion.of(11)`
+  - Java plugin [docs](https://docs.gradle.org/current/userguide/java_plugin.html#toolchain_and_compatibility):
+    - sourceCompatibility
+    - targetCompatibility

src/setup-java.ts

@@ -1,7 +1,7 @@
 import fs from 'fs';
 import * as core from '@actions/core';
 import * as auth from './auth';
-import { getBooleanInput, isCacheFeatureAvailable, getVersionFromFileContent } from './util';
+import { getBooleanInput, isCacheFeatureAvailable, getVersionFromFile } from './util';
 import * as toolchains from './toolchains';
 import * as constants from './constants';
 import { restore } from './cache';
@@ -47,7 +47,7 @@ async function run() {
         .toString()
         .trim();
 
-      const version = getVersionFromFileContent(versionFile, content, distributionName);
+      const version = getVersionFromFile(versionFile, content, distributionName);
       core.debug(`Parsed version from file '${version}'`);
 
       if (!version) {

src/util.ts

@@ -9,6 +9,7 @@ import * as tc from '@actions/tool-cache';
 import { INPUT_JOB_STATUS, DISTRIBUTIONS_ONLY_MAJOR_VERSION } from './constants';
 import { create } from 'xmlbuilder2';
 import { XMLBuilder } from 'xmlbuilder2/lib/interfaces';
+import { on } from 'events';
 
 export function getTempDir() {
   let tempDirectory = process.env['RUNNER_TEMP'] || os.tmpdir();
@@ -102,31 +103,33 @@ export function isCacheFeatureAvailable(): boolean {
   return false;
 }
 
-export function getVersionFromFileContent(
+export function getVersionFromFile(
   fileName: string,
   content: string,
   distributionName: string
 ): string | null {
-  let fileContent = null;
+  let parsedVersion = null;
 
   core.debug(`Getting version from: '${fileName}'`);
   if (fileName.includes('.java-version')) {
-    fileContent = parseJavaVersionFile(content);
+    parsedVersion = parseJavaVersionFile(content);
   } else if (fileName.includes('pom.xml')) {
-    fileContent = parsePomXmlFile(content);
+    parsedVersion = parsePomXmlFile(content);
+  } else if (fileName.includes('build.gradle')) {
+    parsedVersion = parseBuildGradleFile(content);
   } else {
     throw new Error(
       `File ${fileName} not supported, files supported: '.java-version' and 'pom.xml'`
     );
   }
 
-  if (!fileContent) {
+  if (!parsedVersion) {
     return null;
   }
 
-  core.debug(`Version from file '${fileContent}'`);
+  core.debug(`Version from file '${parsedVersion}'`);
 
-  const tentativeVersion = avoidOldNotation(fileContent);
+  const tentativeVersion = avoidOldNotation(parsedVersion);
   const rawVersion = tentativeVersion.split('-')[0];
 
   let version = semver.validRange(rawVersion) ? tentativeVersion : semver.coerce(tentativeVersion);
@@ -177,12 +180,9 @@ function parsePomXmlFile(xmlFileAsString: string): string | null {
 }
 
 function getByMavenProperties(xmlDoc: XMLBuilder): string | null {
-  const possibleTagsRegex = [
-    'maven.compiler.source',
-    'maven.compiler.release',
-  ];
+  const versionTags = ['maven.compiler.source', 'maven.compiler.release'];
 
-  for (var tag of possibleTagsRegex) {
+  for (const tag of versionTags) {
     const version = getVersionByTagName(xmlDoc, tag);
 
     if (version !== null) {
@@ -206,36 +206,42 @@ function getVersionByTagName(xmlDoc: XMLBuilder, tag: string): string | null {
   } else {
     return null;
   }
-
 }
 
 function getByMavenCompilerPluginConfig(xmlDoc: XMLBuilder): string | null {
   const source = xmlDoc.find(n => {
     // Find <source> node
-    if (n.node.nodeName !== "source") {
+    if (n.node.nodeName !== 'source') {
       return false;
     }
     if (n.node.childNodes.length !== 1) {
       return false;
     }
     // Must be within <configuration>
-    if (n.up().node.nodeName !== "configuration") {
+    if (n.up().node.nodeName !== 'configuration') {
       return false;
     }
     // Which must be inside <plugin>
-    if (n.up().up().node.nodeName !== "plugin") {
+    if (n.up().up().node.nodeName !== 'plugin') {
       return false;
     }
     // Make sure the plugin is maven-compiler-plugin
-    const isCompilerPlugin = n.up().up().some(c => {
-      if (c.node.nodeName !== "artifactId") {
-        return false;
-      }
-      if (c.node.childNodes.length !== 1) {
-        return false;
-      }
-      return c.first().toString() === "maven-compiler-plugin";
-    }, false, true);
+    const isCompilerPlugin = n
+      .up()
+      .up()
+      .some(
+        c => {
+          if (c.node.nodeName !== 'artifactId') {
+            return false;
+          }
+          if (c.node.childNodes.length !== 1) {
+            return false;
+          }
+          return c.first().toString() === 'maven-compiler-plugin';
+        },
+        false,
+        true
+      );
     if (!isCompilerPlugin) {
       return false;
     }
@@ -246,6 +252,52 @@ function getByMavenCompilerPluginConfig(xmlDoc: XMLBuilder): string | null {
   return source?.first().toString() ?? null;
 }
 
+function parseBuildGradleFile(buildGradle: string): any {
+  const versionDefinitionTypes = [getByJavaLibraryPlugin, getByJavaPlugin];
+
+  for (const definitionType of versionDefinitionTypes) {
+    const version = definitionType(buildGradle);
+
+    if (version !== null) {
+      return version;
+    }
+  }
+
+  return null;
+}
+
+function getByJavaLibraryPlugin(buildGradle: string) {
+  return getVersionByRegex(buildGradle, 'JavaLanguageVersion.of((d+))');
+}
+
+function getByJavaPlugin(buildGradle: string) {
+  const possibleRegex = [
+    'sourceCompatibilitys?=s?JavaVersion.VERSION_(?:1_)?(d+)',
+    'targetCompatibilitys?=s?JavaVersion.VERSION_(?:1_)?(d+)'
+  ];
+
+  for (var regex of possibleRegex) {
+    const version = getVersionByRegex(buildGradle, regex);
+
+    if (version !== null) {
+      return version;
+    }
+  }
+
+  return null;
+}
+
+function getVersionByRegex(content: string, regex: string): string | null {
+  const match = content.match(new RegExp(regex));
+
+  if (match) {
+    core.debug(`Found java version: '${match[1]}' using regex: '${regex}'`);
+    return match[1];
+  } else {
+    return null;
+  }
+}
+
 // By convention, action expects version 8 in the format `8.*` instead of `1.8`
 function avoidOldNotation(content: string): string {
   return content.startsWith('1.') ? content.substring(2) : content;