Support pinning java-version as "latest"

README.md

@@ -106,6 +106,14 @@ The `java-version` input supports an exact version or a version range using [Sem
 - more specific versions: `8.0.282+8`, `8.0.232`, `11.0`, `11.0.4`, `17.0`
 - multi-field Java versions (JEP 322), such as: `11.0.9.1`, `18.0.1.1`
 - early access (EA) versions: `15-ea`, `15.0.0-ea`
+- the `latest` alias, which floats to the newest available stable (GA) release
+
+> [!NOTE]
+> - `latest` always resolves the newest version from the distribution's remote metadata (it behaves like `check-latest: true`), so it ignores any older version already present in the runner tool cache. This has the same performance trade-off described in [Check latest](#check-latest).
+> - `latest` is only supported through the `java-version` input, not through `java-version-file`, and it resolves stable (GA) releases only — it cannot be combined with `-ea`.
+> - The `jdkfile` distribution does not support `latest`, as it installs from a local file.
+> - For `oracle` and `graalvm` (Oracle GraalVM), `latest` uses the Adoptium API only to determine the newest GA **major version number** — the JDK binary itself is still downloaded from the Oracle / GraalVM servers for that major. Because these distributions have no endpoint to list their own releases, if their servers haven't published the resolved major yet, the action fails and asks you to specify a concrete version. Note the Oracle JDK license caveat below still applies to a floating `latest`.
+> - For `graalvm-community`, `latest` floats to the newest GA release published on GitHub, so it never depends on the Adoptium API and always resolves to the newest major that GraalVM Community actually ships.
 
 #### Supported distributions
 Currently, the following distributions are supported:

__tests__/distributors/base-installer.test.ts

@@ -420,6 +420,29 @@ describe('setupJava', () => {
     expect(spyCoreInfo).not.toHaveBeenCalledWith('Trying to download...');
   });
 
+  it('should resolve the latest version from remote when java-version is "latest", even if a version is cached', async () => {
+    mockJavaBase = new EmptyJavaBase({
+      version: 'latest',
+      architecture: 'x86',
+      packageType: 'jdk',
+      checkLatest: false
+    });
+
+    await expect(mockJavaBase.setupJava()).resolves.toEqual({
+      version: actualJavaVersion,
+      path: javaPathInstalled
+    });
+
+    // `latest` must bypass the tool-cache short-circuit and always resolve remotely
+    expect(spyCoreInfo).toHaveBeenCalledWith(
+      'Trying to resolve the latest version from remote'
+    );
+    expect(spyCoreInfo).toHaveBeenCalledWith('Trying to download...');
+    expect(spyCoreInfo).not.toHaveBeenCalledWith(
+      `Resolved Java ${installedJavaVersion} from tool-cache`
+    );
+  });
+
   it.each([
     [
       {
@@ -744,15 +767,18 @@ describe('normalizeVersion', () => {
   const DummyJavaBase = JavaBase as any;
 
   it.each([
-    ['11', {version: '11', stable: true}],
-    ['11.0', {version: '11.0', stable: true}],
-    ['11.0.10', {version: '11.0.10', stable: true}],
-    ['11-ea', {version: '11', stable: false}],
-    ['11.0.2-ea', {version: '11.0.2', stable: false}],
-    ['18.0.1.1', {version: '18.0.1+1', stable: true}],
-    ['11.0.9.1', {version: '11.0.9+1', stable: true}],
-    ['12.0.2.1.0', {version: '12.0.2+1.0', stable: true}],
-    ['18.0.1.1-ea', {version: '18.0.1+1', stable: false}]
+    ['11', {version: '11', stable: true, latest: false}],
+    ['11.0', {version: '11.0', stable: true, latest: false}],
+    ['11.0.10', {version: '11.0.10', stable: true, latest: false}],
+    ['11-ea', {version: '11', stable: false, latest: false}],
+    ['11.0.2-ea', {version: '11.0.2', stable: false, latest: false}],
+    ['18.0.1.1', {version: '18.0.1+1', stable: true, latest: false}],
+    ['11.0.9.1', {version: '11.0.9+1', stable: true, latest: false}],
+    ['12.0.2.1.0', {version: '12.0.2+1.0', stable: true, latest: false}],
+    ['18.0.1.1-ea', {version: '18.0.1+1', stable: false, latest: false}],
+    ['latest', {version: 'x', stable: true, latest: true}],
+    ['LATEST', {version: 'x', stable: true, latest: true}],
+    ['  Latest  ', {version: 'x', stable: true, latest: true}]
   ])('normalizeVersion from %s to %s', (input, expected) => {
     expect(DummyJavaBase.prototype.normalizeVersion.call(null, input)).toEqual(
       expected
@@ -767,6 +793,17 @@ describe('normalizeVersion', () => {
       `The string '${version}' is not valid SemVer notation for a Java version. Please check README file for code snippets and more detailed information`
     );
   });
+
+  it.each(['latest-ea', 'latest.1', 'LATEST-EA', '  latest-ea  '])(
+    'normalizeVersion should throw a targeted error for latest combined with a qualifier (%s)',
+    version => {
+      expect(
+        DummyJavaBase.prototype.normalizeVersion.bind(null, version)
+      ).toThrow(
+        `The 'latest' alias resolves stable (GA) releases only and cannot be combined with '-ea' or other qualifiers (received '${version}'). Use 'latest' on its own, or specify a concrete version.`
+      );
+    }
+  );
 });
 
 describe('createVersionNotFoundError', () => {

__tests__/distributors/corretto-installer.test.ts

@@ -204,6 +204,24 @@ describe('getAvailableVersions', () => {
       expect(availableVersion.url).toBe(expectedLink);
     });
 
+    it('with latest resolves to the newest available major version', async () => {
+      const distribution = new CorrettoDistribution({
+        version: 'latest',
+        architecture: 'x64',
+        packageType: 'jdk',
+        checkLatest: false
+      });
+      mockPlatform(distribution, 'linux');
+
+      const availableVersion =
+        await distribution['findPackageForDownload']('x');
+      expect(availableVersion).not.toBeNull();
+      // 18 is the newest major present in the mocked Corretto index
+      expect(availableVersion.url).toBe(
+        'https://corretto.aws/downloads/resources/18.0.0.37.1/amazon-corretto-18.0.0.37.1-linux-x64.tar.gz'
+      );
+    });
+
     it('with unstable version expect to throw not supported error', async () => {
       const version = '18.0.1-ea';
       const distribution = new CorrettoDistribution({

__tests__/distributors/graalvm-installer.test.ts

@@ -417,6 +417,61 @@ describe('GraalVMDistribution', () => {
         );
       });
 
+      describe('latest alias', () => {
+        it('resolves the newest major version from the Adoptium API', async () => {
+          const latestDistribution = new GraalVMDistribution({
+            ...defaultOptions,
+            version: 'latest'
+          });
+          (latestDistribution as any).http = mockHttpClient;
+          jest
+            .spyOn(latestDistribution, 'getPlatform')
+            .mockReturnValue('linux');
+          mockHttpClient.getJson.mockResolvedValue({
+            statusCode: 200,
+            result: {most_recent_feature_release: 25},
+            headers: {}
+          });
+          mockHttpClient.head.mockResolvedValue({
+            message: {statusCode: 200}
+          });
+
+          const result = await (
+            latestDistribution as any
+          ).findPackageForDownload('x');
+
+          expect(result).toEqual({
+            url: 'https://download.oracle.com/graalvm/25/latest/graalvm-jdk-25_linux-x64_bin.tar.gz',
+            version: '25'
+          });
+        });
+
+        it('throws an actionable error when the latest major is not yet available', async () => {
+          const latestDistribution = new GraalVMDistribution({
+            ...defaultOptions,
+            version: 'latest'
+          });
+          (latestDistribution as any).http = mockHttpClient;
+          jest
+            .spyOn(latestDistribution, 'getPlatform')
+            .mockReturnValue('linux');
+          mockHttpClient.getJson.mockResolvedValue({
+            statusCode: 200,
+            result: {most_recent_feature_release: 25},
+            headers: {}
+          });
+          mockHttpClient.head.mockResolvedValue({
+            message: {statusCode: 404}
+          });
+
+          await expect(
+            (latestDistribution as any).findPackageForDownload('x')
+          ).rejects.toThrow(
+            /is not yet available for the GraalVM distribution/
+          );
+        });
+      });
+
       it('should throw error for JDK versions less than 17', async () => {
         await expect(
           (distribution as any).findPackageForDownload('11')
@@ -1115,6 +1170,60 @@ describe('GraalVMDistribution', () => {
         });
       });
 
+      it('resolves latest to the newest GA across all Community majors without calling Adoptium', async () => {
+        const latestCommunity = new GraalVMCommunityDistribution({
+          ...defaultOptions,
+          version: 'latest'
+        });
+        (latestCommunity as any).http = mockHttpClient;
+        jest.spyOn(latestCommunity, 'getPlatform').mockReturnValue('linux');
+
+        mockHttpClient.getJson.mockResolvedValue({
+          result: [
+            {
+              draft: false,
+              prerelease: false,
+              assets: [
+                {
+                  name: 'graalvm-community-jdk-21.0.2_linux-x64_bin.tar.gz',
+                  browser_download_url:
+                    'https://github.com/graalvm/graalvm-ce-builds/releases/download/jdk-21.0.2/graalvm-community-jdk-21.0.2_linux-x64_bin.tar.gz'
+                }
+              ]
+            },
+            {
+              draft: false,
+              prerelease: false,
+              assets: [
+                {
+                  name: 'graalvm-community-jdk-24.0.1_linux-x64_bin.tar.gz',
+                  browser_download_url:
+                    'https://github.com/graalvm/graalvm-ce-builds/releases/download/jdk-24.0.1/graalvm-community-jdk-24.0.1_linux-x64_bin.tar.gz'
+                }
+              ]
+            }
+          ],
+          statusCode: 200,
+          headers: {}
+        });
+
+        const result = await (latestCommunity as any).findPackageForDownload(
+          'x'
+        );
+
+        expect(result).toEqual({
+          url: 'https://github.com/graalvm/graalvm-ce-builds/releases/download/jdk-24.0.1/graalvm-community-jdk-24.0.1_linux-x64_bin.tar.gz',
+          version: '24.0.1'
+        });
+        // The Community release list is authoritative, so the Adoptium
+        // most_recent_feature_release endpoint must not be consulted.
+        expect(mockHttpClient.getJson).toHaveBeenCalledTimes(1);
+        expect(mockHttpClient.getJson).toHaveBeenCalledWith(
+          expect.stringContaining('graalvm-ce-builds/releases'),
+          expect.anything()
+        );
+      });
+
       it('should reject GraalVM Community early access requests', async () => {
         (communityDistribution as any).stable = false;
 

__tests__/distributors/local-installer.test.ts

@@ -170,6 +170,20 @@ describe('setupJava', () => {
     jest.restoreAllMocks();
   });
 
+  it('throws for the latest alias since jdkfile has no version list', async () => {
+    const inputs = {
+      version: 'latest',
+      architecture: 'x86',
+      packageType: 'jdk',
+      checkLatest: false
+    };
+
+    mockJavaBase = new LocalDistribution(inputs, expectedJdkFile);
+    await expect(mockJavaBase.setupJava()).rejects.toThrow(
+      "The 'latest' version alias is not supported for the 'jdkfile' distribution. Please specify a concrete version."
+    );
+  });
+
   it('java is resolved from toolcache, jdkfile is untouched', async () => {
     const inputs = {
       version: actualJavaVersion,

__tests__/distributors/oracle-installer.test.ts

@@ -174,3 +174,59 @@ describe('findPackageForDownload', () => {
     );
   });
 });
+describe('findPackageForDownload with latest', () => {
+  let spyHttpClientHead: any;
+  let spyHttpClientGetJson: any;
+
+  beforeEach(() => {
+    (core.debug as jest.Mock).mockImplementation(() => {});
+    (core.error as jest.Mock).mockImplementation(() => {});
+    spyHttpClientGetJson = jest.spyOn(HttpClient.prototype, 'getJson');
+    spyHttpClientGetJson.mockResolvedValue({
+      statusCode: 200,
+      result: {most_recent_feature_release: 25},
+      headers: {}
+    });
+  });
+
+  afterEach(() => {
+    jest.restoreAllMocks();
+  });
+
+  it('resolves the newest major version from the Adoptium API', async () => {
+    spyHttpClientHead = jest.spyOn(HttpClient.prototype, 'head');
+    spyHttpClientHead.mockResolvedValue({message: {statusCode: 200}});
+
+    const distribution = new OracleDistribution({
+      version: 'latest',
+      architecture: 'x64',
+      packageType: 'jdk',
+      checkLatest: false
+    });
+
+    const result = await distribution['findPackageForDownload']('x');
+    const osType = distribution.getPlatform();
+    const archiveType = getDownloadArchiveExtension();
+
+    expect(result.version).toBe('25');
+    expect(result.url).toBe(
+      `https://download.oracle.com/java/25/latest/jdk-25_${osType}-x64_bin.${archiveType}`
+    );
+  });
+
+  it('throws an actionable error when the latest major is not yet available', async () => {
+    spyHttpClientHead = jest.spyOn(HttpClient.prototype, 'head');
+    spyHttpClientHead.mockResolvedValue({message: {statusCode: 404}});
+
+    const distribution = new OracleDistribution({
+      version: 'latest',
+      architecture: 'x64',
+      packageType: 'jdk',
+      checkLatest: false
+    });
+
+    await expect(distribution['findPackageForDownload']('x')).rejects.toThrow(
+      /is not yet available for the Oracle JDK distribution/
+    );
+  });
+});

__tests__/distributors/temurin-installer.test.ts

@@ -312,6 +312,24 @@ describe('findPackageForDownload', () => {
     expect(resolvedVersion.signatureUrl).toBeDefined();
   });
 
+  it('version "latest" is normalized to the newest available version', async () => {
+    const distribution = new TemurinDistribution(
+      {
+        version: 'latest',
+        architecture: 'x64',
+        packageType: 'jdk',
+        checkLatest: false
+      },
+      TemurinImplementation.Hotspot
+    );
+    distribution['getAvailableVersions'] = async () => manifestData as any;
+    // normalizeVersion turns `latest` into the wildcard carried on `this.version`
+    const resolvedVersion = await distribution['findPackageForDownload'](
+      distribution['version']
+    );
+    expect(resolvedVersion.version).toBe('16.0.2+7');
+  });
+
   it('version is found but binaries list is empty', async () => {
     const distribution = new TemurinDistribution(
       {

__tests__/util.test.ts

@@ -56,7 +56,8 @@ const {
   isVersionSatisfies,
   isCacheFeatureAvailable,
   isGhes,
-  validatePaginationUrl
+  validatePaginationUrl,
+  getLatestMajorVersion
 } = await import('../src/util.js');
 
 describe('isVersionSatisfies', () => {
@@ -400,3 +401,33 @@ describe('isGhes', () => {
     expect(isGhes()).toBeTruthy();
   });
 });
+
+describe('getLatestMajorVersion', () => {
+  const makeHttp = (getJson: jest.Mock) =>
+    ({getJson}) as unknown as import('@actions/http-client').HttpClient;
+
+  it('returns most_recent_feature_release from the Adoptium API', async () => {
+    const getJson = jest.fn(async () => ({
+      statusCode: 200,
+      result: {most_recent_feature_release: 25},
+      headers: {}
+    }));
+
+    await expect(getLatestMajorVersion(makeHttp(getJson))).resolves.toBe(25);
+    expect(getJson).toHaveBeenCalledWith(
+      'https://api.adoptium.net/v3/info/available_releases'
+    );
+  });
+
+  it('throws when the response does not contain a usable value', async () => {
+    const getJson = jest.fn(async () => ({
+      statusCode: 200,
+      result: {},
+      headers: {}
+    }));
+
+    await expect(getLatestMajorVersion(makeHttp(getJson))).rejects.toThrow(
+      'Could not determine the latest available Java major version'
+    );
+  });
+});

action.yml

@@ -4,7 +4,7 @@ description: 'Set up a specific version of the Java JDK and add the
 author: 'GitHub'
 inputs:
   java-version:
-    description: 'The Java version to set up. Takes a whole or semver Java version. See examples of supported syntax in README file'
+    description: 'The Java version to set up. Takes a whole or semver Java version, or the "latest" alias to use the newest available stable release. See examples of supported syntax in README file'
     required: false
   java-version-file:
     description: 'The path to a file containing the Java version to set up (.java-version, .tool-versions, .sdkmanrc). Used when java-version is not set. See examples of supported syntax in README file'