Support pinning java-version as "latest"

Add a `latest` alias for the `java-version` input that floats to the newest
available stable (GA) release. It is normalized to the SemVer wildcard at the
base-installer layer and always resolves from remote (like `check-latest: true`).

List-based distributions resolve it automatically via the existing newest-first
matching. Corretto selects its newest available major; Oracle and GraalVM look up
the newest GA major via the Adoptium API and request it, failing with an actionable
error if that major isn't published yet. The jdkfile distribution rejects `latest`.

Closes #832

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

README.md

@@ -105,6 +105,13 @@ The `java-version` input supports an exact version or a version range using [Sem
 - major versions, such as: `8`, `11`, `16`, `17`, `21`, `25`
 - more specific versions: `8.0.282+8`, `8.0.232`, `11.0`, `11.0.4`, `17.0`
 - 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`, `latest` resolves the newest GA major version via the Adoptium API and then requests it from the distribution. If that distribution hasn't published the newest 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`.
 
 #### 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([
     [
       {
@@ -744,11 +767,14 @@ 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}]
+    ['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}],
+    ['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

__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')

__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'

dist/cleanup/index.js

@@ -96154,6 +96154,22 @@ function renameWinArchive(javaArchivePath) {
     fs.renameSync(javaArchivePath, javaArchivePathRenamed);
     return javaArchivePathRenamed;
 }
+// Resolve the newest available stable/GA feature (major) release.
+//
+// Some distributions (e.g. Oracle, GraalVM) construct their download URLs from a
+// concrete major version and don't expose an endpoint to list every available
+// release, so a bare `latest` alias can't be resolved from their own metadata.
+// The Adoptium (Temurin) API is used as a proxy for "what is the newest GA major
+// version out there", which those distributions typically publish at the same time.
+async function getLatestMajorVersion(http) {
+    const availableReleasesUrl = 'https://api.adoptium.net/v3/info/available_releases';
+    const response = await http.getJson(availableReleasesUrl);
+    const mostRecent = response.result?.most_recent_feature_release;
+    if (!mostRecent || Number.isNaN(Number(mostRecent))) {
+        throw new Error(`Could not determine the latest available Java major version from ${availableReleasesUrl}`);
+    }
+    return Number(mostRecent);
+}
 
 ;// CONCATENATED MODULE: ./src/gpg.ts
 

dist/setup/index.js

@@ -127146,6 +127146,22 @@ function renameWinArchive(javaArchivePath) {
     external_fs_namespaceObject.renameSync(javaArchivePath, javaArchivePathRenamed);
     return javaArchivePathRenamed;
 }
+// Resolve the newest available stable/GA feature (major) release.
+//
+// Some distributions (e.g. Oracle, GraalVM) construct their download URLs from a
+// concrete major version and don't expose an endpoint to list every available
+// release, so a bare `latest` alias can't be resolved from their own metadata.
+// The Adoptium (Temurin) API is used as a proxy for "what is the newest GA major
+// version out there", which those distributions typically publish at the same time.
+async function getLatestMajorVersion(http) {
+    const availableReleasesUrl = 'https://api.adoptium.net/v3/info/available_releases';
+    const response = await http.getJson(availableReleasesUrl);
+    const mostRecent = response.result?.most_recent_feature_release;
+    if (!mostRecent || Number.isNaN(Number(mostRecent))) {
+        throw new Error(`Could not determine the latest available Java major version from ${availableReleasesUrl}`);
+    }
+    return Number(mostRecent);
+}
 
 ;// CONCATENATED MODULE: ./src/gpg.ts
 
@@ -131045,6 +131061,7 @@ class JavaBase {
     architecture;
     packageType;
     stable;
+    latest;
     checkLatest;
     setDefault;
     verifySignature;
@@ -131055,7 +131072,11 @@ class JavaBase {
             allowRetries: true,
             maxRetries: 3
         });
-        ({ version: this.version, stable: this.stable } = this.normalizeVersion(installerOptions.version));
+        ({
+            version: this.version,
+            stable: this.stable,
+            latest: this.latest
+        } = this.normalizeVersion(installerOptions.version));
         this.architecture = installerOptions.architecture || external_os_default().arch();
         this.packageType = installerOptions.packageType;
         this.checkLatest = installerOptions.checkLatest;
@@ -131071,7 +131092,7 @@ class JavaBase {
             throw new Error(`Input 'verify-signature' is not supported for distribution '${this.distribution}'.`);
         }
         let foundJava = this.findInToolcache();
-        if (foundJava && !this.checkLatest) {
+        if (foundJava && !this.checkLatest && !this.latest) {
             info(`Resolved Java ${foundJava.version} from tool-cache`);
         }
         else {
@@ -131249,6 +131270,17 @@ class JavaBase {
     }
     normalizeVersion(version) {
         let stable = true;
+        const latest = false;
+        // Support the `latest` alias (case-insensitive), which floats to the newest
+        // available stable/GA release. It is translated to the SemVer wildcard `x`
+        // so the existing "newest satisfying version wins" resolution applies.
+        if (version.trim().toLowerCase() === 'latest') {
+            return {
+                version: 'x',
+                stable: true,
+                latest: true
+            };
+        }
         if (version.endsWith('-ea')) {
             version = version.replace(/-ea$/, '');
             stable = false;
@@ -131263,7 +131295,8 @@ class JavaBase {
         }
         return {
             version,
-            stable
+            stable,
+            latest
         };
     }
     createVersionNotFoundError(versionOrRange, availableVersions, additionalContext) {
@@ -131337,6 +131370,9 @@ class LocalDistribution extends JavaBase {
         this.jdkFile = jdkFile;
     }
     async setupJava() {
+        if (this.latest) {
+            throw new Error("The 'latest' version alias is not supported for the 'jdkfile' distribution. Please specify a concrete version.");
+        }
         let foundJava = this.findInToolcache();
         if (foundJava) {
             info(`Resolved Java ${foundJava.version} from tool-cache`);
@@ -132352,10 +132388,20 @@ class CorrettoDistribution extends JavaBase {
         if (!this.stable) {
             throw new Error('Early access versions are not supported');
         }
+        const availableVersions = await this.getAvailableVersions();
+        // The `latest` alias is normalized to the SemVer wildcard, but Corretto
+        // matches on an exact major version, so resolve it to the newest available
+        // major from Corretto's own list.
+        if (this.latest) {
+            const latestMajor = availableVersions
+                .map(item => parseInt(item.version, 10))
+                .filter(major => !Number.isNaN(major))
+                .reduce((max, current) => (current > max ? current : max), 0);
+            version = latestMajor.toString();
+        }
         if (version.includes('.')) {
             throw new Error('Only major versions are supported');
         }
-        const availableVersions = await this.getAvailableVersions();
         const matchingVersions = availableVersions
             .filter(item => item.version == version)
             .map(item => {
@@ -132483,6 +132529,13 @@ class OracleDistribution extends JavaBase {
         }
         const platform = this.getPlatform();
         const extension = getDownloadArchiveExtension();
+        // The `latest` alias is normalized to the SemVer wildcard. Oracle builds its
+        // download URLs from a concrete major and has no endpoint to list releases,
+        // so resolve the newest available GA major from the Adoptium API and use it.
+        if (this.latest) {
+            const latestMajor = await getLatestMajorVersion(this.http);
+            range = latestMajor.toString();
+        }
         const isOnlyMajorProvided = !range.includes('.');
         const major = isOnlyMajorProvided ? range : range.split('.')[0];
         const possibleUrls = [];
@@ -132509,6 +132562,11 @@ class OracleDistribution extends JavaBase {
                 throw new Error(`Http request for Oracle JDK failed with status code: ${response.message.statusCode}`);
             }
         }
+        if (this.latest) {
+            const error = this.createVersionNotFoundError(range);
+            error.message += `\nThe latest Java major version (${range}) is not yet available for the Oracle JDK distribution. Please specify a concrete version instead of 'latest'.`;
+            throw error;
+        }
         throw this.createVersionNotFoundError(range);
     }
     getPlatform(platform = process.platform) {
@@ -132907,6 +132965,12 @@ class GraalVMDistribution extends JavaBase {
         if (!this.stable) {
             return this.findEABuildDownloadUrl(`${range}-ea`);
         }
+        // The `latest` alias is normalized to the SemVer wildcard. Oracle GraalVM
+        // builds its download URLs from a concrete major and has no endpoint to list
+        // releases, so resolve the newest available GA major from the Adoptium API.
+        if (this.latest) {
+            range = (await getLatestMajorVersion(this.http)).toString();
+        }
         const { platform, extension, major } = this.validateStableBuildRequest(range);
         const fileUrl = this.constructFileUrl(range, major, platform, arch, extension);
         const response = await this.http.head(fileUrl);
@@ -132955,6 +133019,9 @@ class GraalVMDistribution extends JavaBase {
         if (statusCode === HttpCodes.NotFound) {
             // Create the standard error with additional hint about checking the download URL
             const error = this.createVersionNotFoundError(range);
+            if (this.latest) {
+                error.message += `\nThe latest Java major version (${range}) is not yet available for the ${this.distribution} distribution. Please specify a concrete version instead of 'latest'.`;
+            }
             error.message += `\nPlease check if this version is available at ${GRAALVM_DOWNLOAD_URL} . Pick a version from the list.`;
             throw error;
         }
@@ -133041,6 +133108,12 @@ class GraalVMCommunityDistribution extends GraalVMDistribution {
         if (!this.stable) {
             throw new Error('GraalVM Community does not provide early access builds');
         }
+        // The `latest` alias is normalized to the SemVer wildcard. Resolve the newest
+        // available GA major from the Adoptium API so it can be matched against the
+        // published GraalVM Community releases.
+        if (this.latest) {
+            range = (await getLatestMajorVersion(this.http)).toString();
+        }
         const arch = this.getSupportedArchitecture();
         const { platform, extension } = this.validateStableBuildRequest(range);
         // GraalVM Community asset names embed the platform, architecture and
@@ -133664,7 +133737,11 @@ async function installVersion(version, options, toolchainId = 0) {
         throw new Error(`No supported distribution was found for input ${distributionName}`);
     }
     const result = await distribution.setupJava();
-    await configureToolchains(version, distributionName, result.path, toolchainIds[toolchainId]);
+    // When the `latest` alias is used, the literal input isn't a real version, so
+    // pass the resolved version to the toolchains configuration instead.
+    const isLatest = version.trim().toLowerCase() === 'latest';
+    const toolchainVersion = isLatest ? result.version : version;
+    await configureToolchains(toolchainVersion, distributionName, result.path, toolchainIds[toolchainId]);
     info('');
     info('Java configuration:');
     info(`  Distribution: ${distributionName}`);

src/distributions/base-installer.ts

@@ -19,6 +19,7 @@ export abstract class JavaBase {
   protected architecture: string;
   protected packageType: string;
   protected stable: boolean;
+  protected latest: boolean;
   protected checkLatest: boolean;
   protected setDefault: boolean;
   protected verifySignature: boolean;
@@ -33,9 +34,11 @@ export abstract class JavaBase {
       maxRetries: 3
     });
 
-    ({version: this.version, stable: this.stable} = this.normalizeVersion(
-      installerOptions.version
-    ));
+    ({
+      version: this.version,
+      stable: this.stable,
+      latest: this.latest
+    } = this.normalizeVersion(installerOptions.version));
     this.architecture = installerOptions.architecture || os.arch();
     this.packageType = installerOptions.packageType;
     this.checkLatest = installerOptions.checkLatest;
@@ -62,7 +65,7 @@ export abstract class JavaBase {
     }
 
     let foundJava = this.findInToolcache();
-    if (foundJava && !this.checkLatest) {
+    if (foundJava && !this.checkLatest && !this.latest) {
       core.info(`Resolved Java ${foundJava.version} from tool-cache`);
     } else {
       core.info('Trying to resolve the latest version from remote');
@@ -263,6 +266,18 @@ export abstract class JavaBase {
 
   protected normalizeVersion(version: string) {
     let stable = true;
+    const latest = false;
+
+    // Support the `latest` alias (case-insensitive), which floats to the newest
+    // available stable/GA release. It is translated to the SemVer wildcard `x`
+    // so the existing "newest satisfying version wins" resolution applies.
+    if (version.trim().toLowerCase() === 'latest') {
+      return {
+        version: 'x',
+        stable: true,
+        latest: true
+      };
+    }
 
     if (version.endsWith('-ea')) {
       version = version.replace(/-ea$/, '');
@@ -281,7 +296,8 @@ export abstract class JavaBase {
 
     return {
       version,
-      stable
+      stable,
+      latest
     };
   }
 

src/distributions/corretto/installer.ts

@@ -59,10 +59,22 @@ export class CorrettoDistribution extends JavaBase {
     if (!this.stable) {
       throw new Error('Early access versions are not supported');
     }
+    const availableVersions = await this.getAvailableVersions();
+
+    // The `latest` alias is normalized to the SemVer wildcard, but Corretto
+    // matches on an exact major version, so resolve it to the newest available
+    // major from Corretto's own list.
+    if (this.latest) {
+      const latestMajor = availableVersions
+        .map(item => parseInt(item.version, 10))
+        .filter(major => !Number.isNaN(major))
+        .reduce((max, current) => (current > max ? current : max), 0);
+      version = latestMajor.toString();
+    }
+
     if (version.includes('.')) {
       throw new Error('Only major versions are supported');
     }
-    const availableVersions = await this.getAvailableVersions();
     const matchingVersions = availableVersions
       .filter(item => item.version == version)
       .map(item => {

src/distributions/graalvm/installer.ts

@@ -16,6 +16,7 @@ import {
   extractJdkFile,
   getDownloadArchiveExtension,
   getGitHubHttpHeaders,
+  getLatestMajorVersion,
   getNextPageUrlFromLinkHeader,
   isVersionSatisfies,
   MAX_PAGINATION_PAGES,
@@ -119,6 +120,13 @@ export class GraalVMDistribution extends JavaBase {
       return this.findEABuildDownloadUrl(`${range}-ea`);
     }
 
+    // The `latest` alias is normalized to the SemVer wildcard. Oracle GraalVM
+    // builds its download URLs from a concrete major and has no endpoint to list
+    // releases, so resolve the newest available GA major from the Adoptium API.
+    if (this.latest) {
+      range = (await getLatestMajorVersion(this.http)).toString();
+    }
+
     const {platform, extension, major} = this.validateStableBuildRequest(range);
 
     const fileUrl = this.constructFileUrl(
@@ -203,6 +211,9 @@ export class GraalVMDistribution extends JavaBase {
     if (statusCode === HttpCodes.NotFound) {
       // Create the standard error with additional hint about checking the download URL
       const error = this.createVersionNotFoundError(range);
+      if (this.latest) {
+        error.message += `\nThe latest Java major version (${range}) is not yet available for the ${this.distribution} distribution. Please specify a concrete version instead of 'latest'.`;
+      }
       error.message += `\nPlease check if this version is available at ${GRAALVM_DOWNLOAD_URL} . Pick a version from the list.`;
       throw error;
     }
@@ -353,6 +364,13 @@ export class GraalVMCommunityDistribution extends GraalVMDistribution {
       throw new Error('GraalVM Community does not provide early access builds');
     }
 
+    // The `latest` alias is normalized to the SemVer wildcard. Resolve the newest
+    // available GA major from the Adoptium API so it can be matched against the
+    // published GraalVM Community releases.
+    if (this.latest) {
+      range = (await getLatestMajorVersion(this.http)).toString();
+    }
+
     const arch = this.getSupportedArchitecture();
     const {platform, extension} = this.validateStableBuildRequest(range);
     // GraalVM Community asset names embed the platform, architecture and

src/distributions/local/installer.ts

@@ -22,6 +22,12 @@ export class LocalDistribution extends JavaBase {
   }
 
   public async setupJava(): Promise<JavaInstallerResults> {
+    if (this.latest) {
+      throw new Error(
+        "The 'latest' version alias is not supported for the 'jdkfile' distribution. Please specify a concrete version."
+      );
+    }
+
     let foundJava = this.findInToolcache();
 
     if (foundJava) {

src/distributions/oracle/installer.ts

@@ -13,6 +13,7 @@ import {
 import {
   extractJdkFile,
   getDownloadArchiveExtension,
+  getLatestMajorVersion,
   renameWinArchive
 } from '../../util.js';
 import {HttpCodes} from '@actions/http-client';
@@ -73,6 +74,14 @@ export class OracleDistribution extends JavaBase {
     const platform = this.getPlatform();
     const extension = getDownloadArchiveExtension();
 
+    // The `latest` alias is normalized to the SemVer wildcard. Oracle builds its
+    // download URLs from a concrete major and has no endpoint to list releases,
+    // so resolve the newest available GA major from the Adoptium API and use it.
+    if (this.latest) {
+      const latestMajor = await getLatestMajorVersion(this.http);
+      range = latestMajor.toString();
+    }
+
     const isOnlyMajorProvided = !range.includes('.');
     const major = isOnlyMajorProvided ? range : range.split('.')[0];
 
@@ -113,6 +122,12 @@ export class OracleDistribution extends JavaBase {
       }
     }
 
+    if (this.latest) {
+      const error = this.createVersionNotFoundError(range);
+      error.message += `\nThe latest Java major version (${range}) is not yet available for the Oracle JDK distribution. Please specify a concrete version instead of 'latest'.`;
+      throw error;
+    }
+
     throw this.createVersionNotFoundError(range);
   }
 

src/setup-java.ts

@@ -186,8 +186,14 @@ async function installVersion(
   }
 
   const result = await distribution.setupJava();
+
+  // When the `latest` alias is used, the literal input isn't a real version, so
+  // pass the resolved version to the toolchains configuration instead.
+  const isLatest = version.trim().toLowerCase() === 'latest';
+  const toolchainVersion = isLatest ? result.version : version;
+
   await toolchains.configureToolchains(
-    version,
+    toolchainVersion,
     distributionName,
     result.path,
     toolchainIds[toolchainId]

src/util.ts

@@ -6,6 +6,7 @@ import * as cache from '@actions/cache';
 import * as core from '@actions/core';
 
 import * as tc from '@actions/tool-cache';
+import * as httpm from '@actions/http-client';
 import {
   INPUT_JOB_STATUS,
   DISTRIBUTIONS_ONLY_MAJOR_VERSION
@@ -382,3 +383,33 @@ export function renameWinArchive(javaArchivePath: string): string {
   fs.renameSync(javaArchivePath, javaArchivePathRenamed);
   return javaArchivePathRenamed;
 }
+
+interface IAdoptiumAvailableReleases {
+  most_recent_feature_release: number;
+}
+
+// Resolve the newest available stable/GA feature (major) release.
+//
+// Some distributions (e.g. Oracle, GraalVM) construct their download URLs from a
+// concrete major version and don't expose an endpoint to list every available
+// release, so a bare `latest` alias can't be resolved from their own metadata.
+// The Adoptium (Temurin) API is used as a proxy for "what is the newest GA major
+// version out there", which those distributions typically publish at the same time.
+export async function getLatestMajorVersion(
+  http: httpm.HttpClient
+): Promise<number> {
+  const availableReleasesUrl =
+    'https://api.adoptium.net/v3/info/available_releases';
+
+  const response =
+    await http.getJson<IAdoptiumAvailableReleases>(availableReleasesUrl);
+
+  const mostRecent = response.result?.most_recent_feature_release;
+  if (!mostRecent || Number.isNaN(Number(mostRecent))) {
+    throw new Error(
+      `Could not determine the latest available Java major version from ${availableReleasesUrl}`
+    );
+  }
+
+  return Number(mostRecent);
+}