feat: Add set-default option (#1017)

* Add set-default option

This option allows to install an additional JDK without making it the
default one.

I have wanted this for quite a long time as I'm running custom GitHub
Actions with Java, which might require a specific JDK and I don't want
to pollute the JDK that is used by the overall workflow calling the
action.
And I'm apparently not alone as there was a preexisting issue.

Fixes #560

* Dedupe setJavaDefault and document multi-version/toolchain behavior

- Refactor setJavaDefault to delegate shared output/env logic to
  setJavaEnvironment, avoiding duplication between the two.
- Document that set-default applies to all JDKs in a multiline
  java-version, and that installed JDKs remain registered in Maven
  toolchains regardless of set-default.

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

* test: fix Prettier formatting in base-installer test

Resolves the failing 'Basic validation / build' format-check on
__tests__/distributors/base-installer.test.ts (line exceeded print width).

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

---------

Co-authored-by: Bruno Borges <brborges@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/workflows/e2e-versions.yml

@@ -669,3 +669,77 @@ jobs:
           JAVA_PATH: ${{ steps.setup-java.outputs.path }}
         run: bash __tests__/verify-java.sh "17.0.10" "$JAVA_PATH"
         shell: bash
+
+  setup-java-set-default:
+    name: set-default option - ${{ matrix.os }}
+    needs: setup-java-major-versions
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [macos-latest, windows-latest, ubuntu-latest]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+      - name: Setup Java 17 as default
+        uses: ./
+        id: setup-java-17
+        with:
+          distribution: 'temurin'
+          java-version: '17'
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Setup Java 21 without setting as default
+        uses: ./
+        id: setup-java-21
+        with:
+          distribution: 'temurin'
+          java-version: '21'
+          set-default: false
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Verify JAVA_HOME still points to Java 17
+        run: |
+          echo "JAVA_HOME=$JAVA_HOME"
+          echo "Java 17 path=${{ steps.setup-java-17.outputs.path }}"
+          if [ "$JAVA_HOME" != "${{ steps.setup-java-17.outputs.path }}" ]; then
+            echo "JAVA_HOME should still point to Java 17"
+            exit 1
+          fi
+        shell: bash
+      - name: Verify java -version reports Java 17
+        run: |
+          JAVA_VERSION=$(java -version 2>&1 | head -1)
+          echo "java -version: $JAVA_VERSION"
+          if ! echo "$JAVA_VERSION" | grep -q "17"; then
+            echo "Default java should still be version 17"
+            exit 1
+          fi
+        shell: bash
+      - name: Verify JAVA_HOME_21 env var is set
+        run: |
+          $envName = "JAVA_HOME_21_${env:RUNNER_ARCH}"
+          $JavaVersionPath = [Environment]::GetEnvironmentVariable($envName)
+          if (-not $JavaVersionPath) {
+            Write-Host "$envName is not set"
+            exit 1
+          }
+          if (-not (Test-Path "$JavaVersionPath")) {
+            Write-Host "$envName path does not exist: $JavaVersionPath"
+            exit 1
+          }
+          Write-Host "$envName=$JavaVersionPath"
+        shell: pwsh
+      - name: Verify Java 21 outputs are set
+        run: |
+          echo "Java 21 path=${{ steps.setup-java-21.outputs.path }}"
+          echo "Java 21 version=${{ steps.setup-java-21.outputs.version }}"
+          if [ -z "${{ steps.setup-java-21.outputs.path }}" ]; then
+            echo "Java 21 path output should be set"
+            exit 1
+          fi
+          if [ -z "${{ steps.setup-java-21.outputs.version }}" ]; then
+            echo "Java 21 version output should be set"
+            exit 1
+          fi
+        shell: bash

README.md

@@ -41,6 +41,8 @@ For more details,  see the full release notes on the [releases page](https://git
 
   - `check-latest`: Setting this option makes the action to check for the latest available version for the version spec.
 
+  - `set-default`: Set to `false` to install a JDK without making it the default. When `false`, `JAVA_HOME` and `PATH` are not updated, but `JAVA_HOME_<major>_<arch>` is still set so the JDK remains discoverable. Default value: `true`. See [Installing JDK without setting as default](docs/advanced-usage.md#Installing-JDK-without-setting-as-default) for more details.
+
   - `verify-signature`: Verifies downloaded Java package signatures when supported by the selected distribution. Currently supported for `temurin` and `microsoft`. If set to `true` for unsupported distributions, the action fails.
 
   - `verify-signature-public-key`: ASCII-armored GPG public key used to verify the downloaded package signature. Overrides the default bundled key for the selected distribution.

__tests__/distributors/base-installer.test.ts

@@ -563,6 +563,110 @@ describe('setupJava', () => {
     expect(spyCoreExportVariable).not.toHaveBeenCalled();
     expect(spyCoreSetOutput).not.toHaveBeenCalled();
   });
+
+  it('should not set JAVA_HOME and PATH when setDefault is false', async () => {
+    mockJavaBase = new EmptyJavaBase({
+      version: '11',
+      architecture: 'x86',
+      packageType: 'jdk',
+      checkLatest: false,
+      setDefault: false
+    });
+    await expect(mockJavaBase.setupJava()).resolves.toEqual({
+      version: installedJavaVersion,
+      path: javaPath
+    });
+    expect(spyCoreExportVariable).not.toHaveBeenCalledWith(
+      'JAVA_HOME',
+      expect.anything()
+    );
+    expect(spyCoreAddPath).not.toHaveBeenCalled();
+    expect(spyCoreExportVariable).toHaveBeenCalledWith(
+      'JAVA_HOME_11_X86',
+      javaPath
+    );
+    expect(spyCoreSetOutput).toHaveBeenCalledWith(
+      'version',
+      installedJavaVersion
+    );
+    expect(spyCoreSetOutput).toHaveBeenCalledWith('path', javaPath);
+    expect(spyCoreSetOutput).toHaveBeenCalledWith('distribution', 'Empty');
+    expect(spyCoreInfo).toHaveBeenCalledWith(
+      `Installing Java ${installedJavaVersion} (not setting as default)`
+    );
+  });
+
+  it('should set JAVA_HOME and PATH when setDefault is true', async () => {
+    mockJavaBase = new EmptyJavaBase({
+      version: '11',
+      architecture: 'x86',
+      packageType: 'jdk',
+      checkLatest: false,
+      setDefault: true
+    });
+    await expect(mockJavaBase.setupJava()).resolves.toEqual({
+      version: installedJavaVersion,
+      path: javaPath
+    });
+    expect(spyCoreExportVariable).toHaveBeenCalledWith('JAVA_HOME', javaPath);
+    expect(spyCoreAddPath).toHaveBeenCalledWith(path.join(javaPath, 'bin'));
+    expect(spyCoreExportVariable).toHaveBeenCalledWith(
+      'JAVA_HOME_11_X86',
+      javaPath
+    );
+    expect(spyCoreInfo).toHaveBeenCalledWith(
+      `Setting Java ${installedJavaVersion} as the default`
+    );
+  });
+
+  it('should default to setting as default when setDefault is not specified', async () => {
+    mockJavaBase = new EmptyJavaBase({
+      version: '11',
+      architecture: 'x86',
+      packageType: 'jdk',
+      checkLatest: false
+    });
+    await expect(mockJavaBase.setupJava()).resolves.toEqual({
+      version: installedJavaVersion,
+      path: javaPath
+    });
+    expect(spyCoreExportVariable).toHaveBeenCalledWith('JAVA_HOME', javaPath);
+    expect(spyCoreAddPath).toHaveBeenCalledWith(path.join(javaPath, 'bin'));
+    expect(spyCoreInfo).toHaveBeenCalledWith(
+      `Setting Java ${installedJavaVersion} as the default`
+    );
+  });
+
+  it('should download and not set default when setDefault is false', async () => {
+    mockJavaBase = new EmptyJavaBase({
+      version: '11',
+      architecture: 'x64',
+      packageType: 'jdk',
+      checkLatest: false,
+      setDefault: false
+    });
+    await expect(mockJavaBase.setupJava()).resolves.toEqual({
+      version: '11.0.9',
+      path: path.join('toolcache', 'Java_Empty_jdk', '11.0.9', 'x64')
+    });
+    expect(spyCoreExportVariable).not.toHaveBeenCalledWith(
+      'JAVA_HOME',
+      expect.anything()
+    );
+    expect(spyCoreAddPath).not.toHaveBeenCalled();
+    expect(spyCoreExportVariable).toHaveBeenCalledWith(
+      'JAVA_HOME_11_X64',
+      path.join('toolcache', 'Java_Empty_jdk', '11.0.9', 'x64')
+    );
+    expect(spyCoreSetOutput).toHaveBeenCalledWith('version', '11.0.9');
+    expect(spyCoreSetOutput).toHaveBeenCalledWith(
+      'path',
+      path.join('toolcache', 'Java_Empty_jdk', '11.0.9', 'x64')
+    );
+    expect(spyCoreInfo).toHaveBeenCalledWith(
+      'Installing Java 11.0.9 (not setting as default)'
+    );
+  });
 });
 
 describe('normalizeVersion', () => {

action.yml

@@ -26,6 +26,10 @@ inputs:
     description: 'Set this option if you want the action to check for the latest available version that satisfies the version spec'
     required: false
     default: false
+  set-default:
+    description: 'Set this option to false if you want to install a JDK but not make it the default. When false, JAVA_HOME and PATH are not updated, but JAVA_HOME_<major>_<arch> is still set.'
+    required: false
+    default: true
   verify-signature:
     description: 'Verify downloaded Java package signatures when supported by the selected distribution'
     required: false

dist/cleanup/index.js

@@ -52241,7 +52241,7 @@ else {
 "use strict";
 
 Object.defineProperty(exports, "__esModule", ({ value: true }));
-exports.DISTRIBUTIONS_ONLY_MAJOR_VERSION = exports.MAVEN_NO_TRANSFER_PROGRESS_LONG_FLAG = exports.MAVEN_NO_TRANSFER_PROGRESS_FLAG = exports.MAVEN_ARGS_ENV = exports.INPUT_SHOW_DOWNLOAD_PROGRESS = exports.INPUT_MVN_TOOLCHAIN_VENDOR = exports.INPUT_MVN_TOOLCHAIN_ID = exports.MVN_TOOLCHAINS_FILE = exports.MVN_SETTINGS_FILE = exports.M2_DIR = exports.STATE_GPG_PRIVATE_KEY_FINGERPRINT = exports.INPUT_JOB_STATUS = exports.INPUT_CACHE_DEPENDENCY_PATH = exports.INPUT_CACHE = exports.INPUT_DEFAULT_GPG_PASSPHRASE = exports.INPUT_DEFAULT_GPG_PRIVATE_KEY = exports.INPUT_GPG_PASSPHRASE = exports.INPUT_GPG_PRIVATE_KEY = exports.INPUT_OVERWRITE_SETTINGS = exports.INPUT_SETTINGS_PATH = exports.INPUT_SERVER_PASSWORD = exports.INPUT_SERVER_USERNAME = exports.INPUT_SERVER_ID = exports.INPUT_VERIFY_SIGNATURE_PUBLIC_KEY = exports.INPUT_VERIFY_SIGNATURE = exports.INPUT_CHECK_LATEST = exports.INPUT_JDK_FILE = exports.INPUT_DISTRIBUTION = exports.INPUT_JAVA_PACKAGE = exports.INPUT_ARCHITECTURE = exports.INPUT_JAVA_VERSION_FILE = exports.INPUT_JAVA_VERSION = exports.MACOS_JAVA_CONTENT_POSTFIX = void 0;
+exports.DISTRIBUTIONS_ONLY_MAJOR_VERSION = exports.MAVEN_NO_TRANSFER_PROGRESS_LONG_FLAG = exports.MAVEN_NO_TRANSFER_PROGRESS_FLAG = exports.MAVEN_ARGS_ENV = exports.INPUT_SHOW_DOWNLOAD_PROGRESS = exports.INPUT_MVN_TOOLCHAIN_VENDOR = exports.INPUT_MVN_TOOLCHAIN_ID = exports.MVN_TOOLCHAINS_FILE = exports.MVN_SETTINGS_FILE = exports.M2_DIR = exports.STATE_GPG_PRIVATE_KEY_FINGERPRINT = exports.INPUT_JOB_STATUS = exports.INPUT_CACHE_DEPENDENCY_PATH = exports.INPUT_CACHE = exports.INPUT_DEFAULT_GPG_PASSPHRASE = exports.INPUT_DEFAULT_GPG_PRIVATE_KEY = exports.INPUT_GPG_PASSPHRASE = exports.INPUT_GPG_PRIVATE_KEY = exports.INPUT_OVERWRITE_SETTINGS = exports.INPUT_SETTINGS_PATH = exports.INPUT_SERVER_PASSWORD = exports.INPUT_SERVER_USERNAME = exports.INPUT_SERVER_ID = exports.INPUT_VERIFY_SIGNATURE_PUBLIC_KEY = exports.INPUT_VERIFY_SIGNATURE = exports.INPUT_SET_DEFAULT = exports.INPUT_CHECK_LATEST = exports.INPUT_JDK_FILE = exports.INPUT_DISTRIBUTION = exports.INPUT_JAVA_PACKAGE = exports.INPUT_ARCHITECTURE = exports.INPUT_JAVA_VERSION_FILE = exports.INPUT_JAVA_VERSION = exports.MACOS_JAVA_CONTENT_POSTFIX = void 0;
 exports.MACOS_JAVA_CONTENT_POSTFIX = 'Contents/Home';
 exports.INPUT_JAVA_VERSION = 'java-version';
 exports.INPUT_JAVA_VERSION_FILE = 'java-version-file';
@@ -52250,6 +52250,7 @@ exports.INPUT_JAVA_PACKAGE = 'java-package';
 exports.INPUT_DISTRIBUTION = 'distribution';
 exports.INPUT_JDK_FILE = 'jdkFile';
 exports.INPUT_CHECK_LATEST = 'check-latest';
+exports.INPUT_SET_DEFAULT = 'set-default';
 exports.INPUT_VERIFY_SIGNATURE = 'verify-signature';
 exports.INPUT_VERIFY_SIGNATURE_PUBLIC_KEY = 'verify-signature-public-key';
 exports.INPUT_SERVER_ID = 'server-id';

dist/setup/index.js

@@ -78001,7 +78001,7 @@ function isProbablyGradleDaemonProblem(packageManager, error) {
 "use strict";
 
 Object.defineProperty(exports, "__esModule", ({ value: true }));
-exports.DISTRIBUTIONS_ONLY_MAJOR_VERSION = exports.MAVEN_NO_TRANSFER_PROGRESS_LONG_FLAG = exports.MAVEN_NO_TRANSFER_PROGRESS_FLAG = exports.MAVEN_ARGS_ENV = exports.INPUT_SHOW_DOWNLOAD_PROGRESS = exports.INPUT_MVN_TOOLCHAIN_VENDOR = exports.INPUT_MVN_TOOLCHAIN_ID = exports.MVN_TOOLCHAINS_FILE = exports.MVN_SETTINGS_FILE = exports.M2_DIR = exports.STATE_GPG_PRIVATE_KEY_FINGERPRINT = exports.INPUT_JOB_STATUS = exports.INPUT_CACHE_DEPENDENCY_PATH = exports.INPUT_CACHE = exports.INPUT_DEFAULT_GPG_PASSPHRASE = exports.INPUT_DEFAULT_GPG_PRIVATE_KEY = exports.INPUT_GPG_PASSPHRASE = exports.INPUT_GPG_PRIVATE_KEY = exports.INPUT_OVERWRITE_SETTINGS = exports.INPUT_SETTINGS_PATH = exports.INPUT_SERVER_PASSWORD = exports.INPUT_SERVER_USERNAME = exports.INPUT_SERVER_ID = exports.INPUT_VERIFY_SIGNATURE_PUBLIC_KEY = exports.INPUT_VERIFY_SIGNATURE = exports.INPUT_CHECK_LATEST = exports.INPUT_JDK_FILE = exports.INPUT_DISTRIBUTION = exports.INPUT_JAVA_PACKAGE = exports.INPUT_ARCHITECTURE = exports.INPUT_JAVA_VERSION_FILE = exports.INPUT_JAVA_VERSION = exports.MACOS_JAVA_CONTENT_POSTFIX = void 0;
+exports.DISTRIBUTIONS_ONLY_MAJOR_VERSION = exports.MAVEN_NO_TRANSFER_PROGRESS_LONG_FLAG = exports.MAVEN_NO_TRANSFER_PROGRESS_FLAG = exports.MAVEN_ARGS_ENV = exports.INPUT_SHOW_DOWNLOAD_PROGRESS = exports.INPUT_MVN_TOOLCHAIN_VENDOR = exports.INPUT_MVN_TOOLCHAIN_ID = exports.MVN_TOOLCHAINS_FILE = exports.MVN_SETTINGS_FILE = exports.M2_DIR = exports.STATE_GPG_PRIVATE_KEY_FINGERPRINT = exports.INPUT_JOB_STATUS = exports.INPUT_CACHE_DEPENDENCY_PATH = exports.INPUT_CACHE = exports.INPUT_DEFAULT_GPG_PASSPHRASE = exports.INPUT_DEFAULT_GPG_PRIVATE_KEY = exports.INPUT_GPG_PASSPHRASE = exports.INPUT_GPG_PRIVATE_KEY = exports.INPUT_OVERWRITE_SETTINGS = exports.INPUT_SETTINGS_PATH = exports.INPUT_SERVER_PASSWORD = exports.INPUT_SERVER_USERNAME = exports.INPUT_SERVER_ID = exports.INPUT_VERIFY_SIGNATURE_PUBLIC_KEY = exports.INPUT_VERIFY_SIGNATURE = exports.INPUT_SET_DEFAULT = exports.INPUT_CHECK_LATEST = exports.INPUT_JDK_FILE = exports.INPUT_DISTRIBUTION = exports.INPUT_JAVA_PACKAGE = exports.INPUT_ARCHITECTURE = exports.INPUT_JAVA_VERSION_FILE = exports.INPUT_JAVA_VERSION = exports.MACOS_JAVA_CONTENT_POSTFIX = void 0;
 exports.MACOS_JAVA_CONTENT_POSTFIX = 'Contents/Home';
 exports.INPUT_JAVA_VERSION = 'java-version';
 exports.INPUT_JAVA_VERSION_FILE = 'java-version-file';
@@ -78010,6 +78010,7 @@ exports.INPUT_JAVA_PACKAGE = 'java-package';
 exports.INPUT_DISTRIBUTION = 'distribution';
 exports.INPUT_JDK_FILE = 'jdkFile';
 exports.INPUT_CHECK_LATEST = 'check-latest';
+exports.INPUT_SET_DEFAULT = 'set-default';
 exports.INPUT_VERIFY_SIGNATURE = 'verify-signature';
 exports.INPUT_VERIFY_SIGNATURE_PUBLIC_KEY = 'verify-signature-public-key';
 exports.INPUT_SERVER_ID = 'server-id';
@@ -78325,6 +78326,10 @@ class JavaBase {
         this.architecture = installerOptions.architecture || os_1.default.arch();
         this.packageType = installerOptions.packageType;
         this.checkLatest = installerOptions.checkLatest;
+        this.setDefault =
+            installerOptions.setDefault !== undefined
+                ? installerOptions.setDefault
+                : true;
         this.verifySignature = (_a = installerOptions.verifySignature) !== null && _a !== void 0 ? _a : false;
         this.verifySignaturePublicKey = installerOptions.verifySignaturePublicKey;
     }
@@ -78445,8 +78450,14 @@ class JavaBase {
             if (process.platform === 'darwin' && fs.existsSync(macOSPostfixPath)) {
                 foundJava.path = macOSPostfixPath;
             }
+            if (this.setDefault) {
                 core.info(`Setting Java ${foundJava.version} as the default`);
                 this.setJavaDefault(foundJava.version, foundJava.path);
+            }
+            else {
+                core.info(`Installing Java ${foundJava.version} (not setting as default)`);
+                this.setJavaEnvironment(foundJava.version, foundJava.path);
+            }
             return foundJava;
         });
     }
@@ -78547,9 +78558,12 @@ class JavaBase {
         return error;
     }
     setJavaDefault(version, toolPath) {
-        const majorVersion = version.split('.')[0];
         core.exportVariable('JAVA_HOME', toolPath);
         core.addPath(path_1.default.join(toolPath, 'bin'));
+        this.setJavaEnvironment(version, toolPath);
+    }
+    setJavaEnvironment(version, toolPath) {
+        const majorVersion = version.split('.')[0];
         core.setOutput('distribution', this.distribution);
         core.setOutput('path', toolPath);
         core.setOutput('version', version);
@@ -80048,8 +80062,14 @@ class LocalDistribution extends base_installer_1.JavaBase {
             if (process.platform === 'darwin' && fs_1.default.existsSync(macOSPostfixPath)) {
                 foundJava.path = macOSPostfixPath;
             }
-            core.info(`Setting Java ${foundJava.version} as default`);
+            if (this.setDefault) {
+                core.info(`Setting Java ${foundJava.version} as the default`);
                 this.setJavaDefault(foundJava.version, foundJava.path);
+            }
+            else {
+                core.info(`Installing Java ${foundJava.version} (not setting as default)`);
+                this.setJavaEnvironment(foundJava.version, foundJava.path);
+            }
             return foundJava;
         });
     }
@@ -81532,6 +81552,7 @@ function run() {
             const cache = core.getInput(constants.INPUT_CACHE);
             const cacheDependencyPath = core.getInput(constants.INPUT_CACHE_DEPENDENCY_PATH);
             const checkLatest = (0, util_1.getBooleanInput)(constants.INPUT_CHECK_LATEST, false);
+            const setDefault = (0, util_1.getBooleanInput)(constants.INPUT_SET_DEFAULT, true);
             const verifySignature = (0, util_1.getBooleanInput)(constants.INPUT_VERIFY_SIGNATURE, false);
             const verifySignaturePublicKey = core.getInput(constants.INPUT_VERIFY_SIGNATURE_PUBLIC_KEY) || undefined;
             let toolchainIds = core.getMultilineInput(constants.INPUT_MVN_TOOLCHAIN_ID);
@@ -81546,6 +81567,7 @@ function run() {
                 architecture,
                 packageType,
                 checkLatest,
+                setDefault,
                 verifySignature,
                 verifySignaturePublicKey,
                 distributionName,
@@ -81582,11 +81604,12 @@ function run() {
 run();
 function installVersion(version, options, toolchainId = 0) {
     return __awaiter(this, void 0, void 0, function* () {
-        const { distributionName, jdkFile, architecture, packageType, checkLatest, verifySignature, verifySignaturePublicKey, toolchainIds } = options;
+        const { distributionName, jdkFile, architecture, packageType, checkLatest, setDefault, verifySignature, verifySignaturePublicKey, toolchainIds } = options;
         const installerOptions = {
             architecture,
             packageType,
             checkLatest,
+            setDefault,
             verifySignature,
             verifySignaturePublicKey,
             version

docs/advanced-usage.md

@@ -16,6 +16,7 @@
 - [Installing custom Java package type](#Installing-custom-Java-package-type)
   - [JavaFX Maven project](#JavaFX-Maven-project)
 - [Installing custom Java architecture](#Installing-custom-Java-architecture)
+- [Installing JDK without setting as default](#Installing-JDK-without-setting-as-default)
 - [Installing custom Java distribution from local file](#Installing-Java-from-local-file)
 - [Testing against different Java distributions](#Testing-against-different-Java-distributions)
 - [Testing against different platforms](#Testing-against-different-platforms)
@@ -297,6 +298,34 @@ steps:
 - run: java --version
 ```
 
+## Installing JDK without setting as default
+
+When installing multiple JDKs, the last one installed becomes the default (`JAVA_HOME`, `PATH`). Use the `set-default` option to install a JDK without overriding the default. The installed JDK is still discoverable via the `JAVA_HOME_<major>_<arch>` environment variable (e.g. `JAVA_HOME_21_X64`).
+
+```yaml
+steps:
+- uses: actions/checkout@v6
+- uses: actions/setup-java@v5
+  with:
+    distribution: 'temurin'
+    java-version: '17'
+- uses: actions/setup-java@v5
+  id: setup-java-21
+  with:
+    distribution: 'temurin'
+    java-version: '21'
+    set-default: false
+- run: |
+    echo "Default java:"
+    java -version
+    echo "Java 21 home: $JAVA_HOME_21_X64"
+    echo "Java 21 path from output: ${{ steps.setup-java-21.outputs.path }}"
+```
+
+In this example, `JAVA_HOME` and `java` on `PATH` point to Java 17, while Java 21 is available via `JAVA_HOME_21_X64` or the step output `path`.
+
+> **Note:** When a single step installs multiple JDKs via a multiline `java-version`, the `set-default` value applies to all of them. With `set-default: false`, none of those JDKs become the default; each remains discoverable through its `JAVA_HOME_<major>_<arch>` variable. Regardless of `set-default`, installed JDKs are still registered in the Maven toolchains file, so they can be selected via Maven toolchains.
+
 ## Installing Java from local file
 If your use-case requires a custom distribution or a version that is not provided by setup-java, you can download it manually and setup-java will take care of the installation and caching on the VM:
 

src/constants.ts

@@ -6,6 +6,7 @@ export const INPUT_JAVA_PACKAGE = 'java-package';
 export const INPUT_DISTRIBUTION = 'distribution';
 export const INPUT_JDK_FILE = 'jdkFile';
 export const INPUT_CHECK_LATEST = 'check-latest';
+export const INPUT_SET_DEFAULT = 'set-default';
 export const INPUT_VERIFY_SIGNATURE = 'verify-signature';
 export const INPUT_VERIFY_SIGNATURE_PUBLIC_KEY = 'verify-signature-public-key';
 export const INPUT_SERVER_ID = 'server-id';

src/distributions/base-installer.ts

@@ -20,6 +20,7 @@ export abstract class JavaBase {
   protected packageType: string;
   protected stable: boolean;
   protected checkLatest: boolean;
+  protected setDefault: boolean;
   protected verifySignature: boolean;
   protected verifySignaturePublicKey: string | undefined;
 
@@ -38,6 +39,10 @@ export abstract class JavaBase {
     this.architecture = installerOptions.architecture || os.arch();
     this.packageType = installerOptions.packageType;
     this.checkLatest = installerOptions.checkLatest;
+    this.setDefault =
+      installerOptions.setDefault !== undefined
+        ? installerOptions.setDefault
+        : true;
     this.verifySignature = installerOptions.verifySignature ?? false;
     this.verifySignaturePublicKey = installerOptions.verifySignaturePublicKey;
   }
@@ -179,8 +184,15 @@ export abstract class JavaBase {
       foundJava.path = macOSPostfixPath;
     }
 
+    if (this.setDefault) {
       core.info(`Setting Java ${foundJava.version} as the default`);
       this.setJavaDefault(foundJava.version, foundJava.path);
+    } else {
+      core.info(
+        `Installing Java ${foundJava.version} (not setting as default)`
+      );
+      this.setJavaEnvironment(foundJava.version, foundJava.path);
+    }
 
     return foundJava;
   }
@@ -312,9 +324,13 @@ export abstract class JavaBase {
   }
 
   protected setJavaDefault(version: string, toolPath: string) {
-    const majorVersion = version.split('.')[0];
     core.exportVariable('JAVA_HOME', toolPath);
     core.addPath(path.join(toolPath, 'bin'));
+    this.setJavaEnvironment(version, toolPath);
+  }
+
+  protected setJavaEnvironment(version: string, toolPath: string) {
+    const majorVersion = version.split('.')[0];
     core.setOutput('distribution', this.distribution);
     core.setOutput('path', toolPath);
     core.setOutput('version', version);

src/distributions/base-models.ts

@@ -3,6 +3,7 @@ export interface JavaInstallerOptions {
   architecture: string;
   packageType: string;
   checkLatest: boolean;
+  setDefault?: boolean;
   verifySignature?: boolean;
   verifySignaturePublicKey?: string;
 }

src/distributions/local/installer.ts

@@ -69,9 +69,15 @@ export class LocalDistribution extends JavaBase {
       foundJava.path = macOSPostfixPath;
     }
 
-    core.info(`Setting Java ${foundJava.version} as default`);
+    if (this.setDefault) {
-
+      core.info(`Setting Java ${foundJava.version} as the default`);
       this.setJavaDefault(foundJava.version, foundJava.path);
+    } else {
+      core.info(
+        `Installing Java ${foundJava.version} (not setting as default)`
+      );
+      this.setJavaEnvironment(foundJava.version, foundJava.path);
+    }
     return foundJava;
   }
 

src/setup-java.ts

@@ -29,6 +29,7 @@ async function run() {
       constants.INPUT_CACHE_DEPENDENCY_PATH
     );
     const checkLatest = getBooleanInput(constants.INPUT_CHECK_LATEST, false);
+    const setDefault = getBooleanInput(constants.INPUT_SET_DEFAULT, true);
     const verifySignature = getBooleanInput(
       constants.INPUT_VERIFY_SIGNATURE,
       false
@@ -51,6 +52,7 @@ async function run() {
       architecture,
       packageType,
       checkLatest,
+      setDefault,
       verifySignature,
       verifySignaturePublicKey,
       distributionName,
@@ -110,6 +112,7 @@ async function installVersion(
     architecture,
     packageType,
     checkLatest,
+    setDefault,
     verifySignature,
     verifySignaturePublicKey,
     toolchainIds
@@ -119,6 +122,7 @@ async function installVersion(
     architecture,
     packageType,
     checkLatest,
+    setDefault,
     verifySignature,
     verifySignaturePublicKey,
     version
@@ -155,6 +159,7 @@ interface installerInputsOptions {
   architecture: string;
   packageType: string;
   checkLatest: boolean;
+  setDefault: boolean;
   verifySignature: boolean;
   verifySignaturePublicKey: string | undefined;
   distributionName: string;