feat: add java generator

.gitignore

@@ -26,4 +26,6 @@ go.work.sum
 dist
 
 # openfeature cli config
-.openfeature.yaml
+.openfeature.yaml
+
+.idea/

cmd/generate.go

@@ -8,6 +8,7 @@ import (
 	"github.com/open-feature/cli/internal/generators"
 	"github.com/open-feature/cli/internal/generators/csharp"
 	"github.com/open-feature/cli/internal/generators/golang"
+	"github.com/open-feature/cli/internal/generators/java"
 	"github.com/open-feature/cli/internal/generators/nestjs"
 	"github.com/open-feature/cli/internal/generators/nodejs"
 	"github.com/open-feature/cli/internal/generators/python"
@@ -257,6 +258,58 @@ func getGenerateCSharpCmd() *cobra.Command {
 	return csharpCmd
 }
 
+func getGenerateJavaCmd() *cobra.Command {
+	javaCmd := &cobra.Command{
+		Use:   "java",
+		Short: "Generate typesafe Java client.",
+		Long:  `Generate typesafe Java client compatible with the OpenFeature Java SDK.`,
+		Annotations: map[string]string{
+			"stability": string(generators.Alpha),
+		},
+		PreRunE: func(cmd *cobra.Command, args []string) error {
+			return initializeConfig(cmd, "generate.java")
+		},
+		RunE: func(cmd *cobra.Command, args []string) error {
+			manifestPath := config.GetManifestPath(cmd)
+			javaPackageName := config.GetJavaPackageName(cmd)
+			outputPath := config.GetOutputPath(cmd)
+
+			logger.Default.GenerationStarted("Java")
+
+			params := generators.Params[java.Params]{
+				OutputPath: outputPath,
+				Custom: java.Params{
+					JavaPackage: javaPackageName,
+				},
+			}
+
+			flagset, err := flagset.Load(manifestPath)
+			if err != nil {
+				return err
+			}
+
+			generator := java.NewGenerator(flagset)
+			logger.Default.Debug("Executing Java generator")
+			err = generator.Generate(&params)
+			if err != nil {
+				return err
+			}
+
+			logger.Default.GenerationComplete("Java")
+
+			return nil
+
+		},
+	}
+
+	// Add Java specific flags
+	config.AddJavaGenerateFlags(javaCmd)
+
+	addStabilityInfo(javaCmd)
+
+	return javaCmd
+}
+
 func getGenerateGoCmd() *cobra.Command {
 	goCmd := &cobra.Command{
 		Use:   "go",
@@ -355,6 +408,7 @@ func init() {
 	generators.DefaultManager.Register(getGenerateGoCmd)
 	generators.DefaultManager.Register(getGenerateNodeJSCmd)
 	generators.DefaultManager.Register(getGeneratePythonCmd)
-  generators.DefaultManager.Register(getGenerateCSharpCmd)
+	generators.DefaultManager.Register(getGenerateCSharpCmd)
 	generators.DefaultManager.Register(GetGenerateNestJsCmd)
+	generators.DefaultManager.Register(getGenerateJavaCmd)
 }

cmd/generate_test.go

@@ -21,7 +21,7 @@ type generateTestCase struct {
 	outputGolden   string // path to the golden output file
 	outputPath     string // output directory (optional, defaults to "output")
 	outputFile     string // output file name
-	packageName    string // optional, used for Go (package-name) and C# (namespace)
+	packageName    string // optional, used for Go (package-name), Java (package-name) and C# (namespace)
 }
 
 func TestGenerate(t *testing.T) {
@@ -70,6 +70,14 @@ func TestGenerate(t *testing.T) {
 			outputFile:     "OpenFeature.g.cs",
 			packageName:    "TestNamespace", // Using packageName field for namespace
 		},
+		{
+			name:           "Java generation success",
+			command:        "java",
+			manifestGolden: "testdata/success_manifest.golden",
+			outputGolden:   "testdata/success_java.golden",
+			outputFile:     "OpenFeature.java",
+			packageName:    "com.example.openfeature",
+		},
 		// Add more test cases here as needed
 	}
 
@@ -107,6 +115,8 @@ func TestGenerate(t *testing.T) {
 					args = append(args, "--namespace", tc.packageName)
 				} else if tc.command == "go" {
 					args = append(args, "--package-name", tc.packageName)
+				} else if tc.command == "java" {
+					args = append(args, "--package-name", tc.packageName)
 				}
 			}
 
@@ -146,6 +156,17 @@ func readOsFileAndWriteToMemMap(t *testing.T, inputPath string, memPath string,
 	}
 }
 
+// normalizeLines trims trailing whitespace and carriage returns from each line.
+// This helps ensure consistent comparison by ignoring formatting differences like indentation or line endings.
+func normalizeLines(input []string) []string {
+	normalized := make([]string, len(input))
+	for i, line := range input {
+		// Trim right whitespace and convert \r\n or \r to \n
+		normalized[i] = strings.TrimRight(line, " \t\r")
+	}
+	return normalized
+}
+
 func compareOutput(t *testing.T, testFile, memoryOutputPath string, fs afero.Fs) {
 	want, err := os.ReadFile(testFile)
 	if err != nil {
@@ -158,8 +179,8 @@ func compareOutput(t *testing.T, testFile, memoryOutputPath string, fs afero.Fs)
 	}
 
 	// Convert to string arrays by splitting on newlines
-	wantLines := strings.Split(string(want), "\n")
-	gotLines := strings.Split(string(got), "\n")
+	wantLines := normalizeLines(strings.Split(string(want), "\n"))
+	gotLines := normalizeLines(strings.Split(string(got), "\n"))
 
 	if diff := cmp.Diff(wantLines, gotLines); diff != "" {
 		t.Errorf("output mismatch (-want +got):\n%s", diff)

cmd/testdata/success_java.golden

@@ -0,0 +1,154 @@
+// AUTOMATICALLY GENERATED BY OPENFEATURE CLI, DO NOT EDIT.
+package com.example.openfeature;
+
+import dev.openfeature.sdk.Client;
+import dev.openfeature.sdk.EvaluationContext;
+import dev.openfeature.sdk.FlagEvaluationDetails;
+import dev.openfeature.sdk.OpenFeatureAPI;
+
+public final class Generated {
+
+    private Generated() {} // prevent instantiation
+
+    public interface GeneratedClient {
+
+        /**
+         * Discount percentage applied to purchases.
+         * Details:
+         * - Flag key: discountPercentage
+         * - Type: Double
+         * - Default value: 0.15
+         * Returns the flag value
+         */
+        Double discountPercentage(EvaluationContext ctx);
+
+        /**
+         * Discount percentage applied to purchases.
+         * Details:
+         * - Flag key: discountPercentage
+         * - Type: Double
+         * - Default value: 0.15
+         * Returns the evaluation details containing the flag value and metadata
+         */
+        FlagEvaluationDetails<Double> discountPercentageDetails(EvaluationContext ctx);
+
+        /**
+         * Controls whether Feature A is enabled.
+         * Details:
+         * - Flag key: enableFeatureA
+         * - Type: Boolean
+         * - Default value: false
+         * Returns the flag value
+         */
+        Boolean enableFeatureA(EvaluationContext ctx);
+
+        /**
+         * Controls whether Feature A is enabled.
+         * Details:
+         * - Flag key: enableFeatureA
+         * - Type: Boolean
+         * - Default value: false
+         * Returns the evaluation details containing the flag value and metadata
+         */
+        FlagEvaluationDetails<Boolean> enableFeatureADetails(EvaluationContext ctx);
+
+        /**
+         * The message to use for greeting users.
+         * Details:
+         * - Flag key: greetingMessage
+         * - Type: String
+         * - Default value: Hello there!
+         * Returns the flag value
+         */
+        String greetingMessage(EvaluationContext ctx);
+
+        /**
+         * The message to use for greeting users.
+         * Details:
+         * - Flag key: greetingMessage
+         * - Type: String
+         * - Default value: Hello there!
+         * Returns the evaluation details containing the flag value and metadata
+         */
+        FlagEvaluationDetails<String> greetingMessageDetails(EvaluationContext ctx);
+
+        /**
+         * Maximum allowed length for usernames.
+         * Details:
+         * - Flag key: usernameMaxLength
+         * - Type: Integer
+         * - Default value: 50
+         * Returns the flag value
+         */
+        Integer usernameMaxLength(EvaluationContext ctx);
+
+        /**
+         * Maximum allowed length for usernames.
+         * Details:
+         * - Flag key: usernameMaxLength
+         * - Type: Integer
+         * - Default value: 50
+         * Returns the evaluation details containing the flag value and metadata
+         */
+        FlagEvaluationDetails<Integer> usernameMaxLengthDetails(EvaluationContext ctx);
+
+    }
+
+    private static final class OpenFeatureGeneratedClient implements GeneratedClient {
+        private final Client client;
+
+        private OpenFeatureGeneratedClient(Client client) {
+            this.client = client;
+        }
+
+
+        @Override
+        public Double discountPercentage(EvaluationContext ctx) {
+            return client.getDoubleValue("discountPercentage", 0.15, ctx);
+        }
+
+        @Override
+        public FlagEvaluationDetails<Double> discountPercentageDetails(EvaluationContext ctx) {
+            return client.getDoubleDetails("discountPercentage", 0.15, ctx);
+        }
+
+        @Override
+        public Boolean enableFeatureA(EvaluationContext ctx) {
+            return client.getBooleanValue("enableFeatureA", false, ctx);
+        }
+
+        @Override
+        public FlagEvaluationDetails<Boolean> enableFeatureADetails(EvaluationContext ctx) {
+            return client.getBooleanDetails("enableFeatureA", false, ctx);
+        }
+
+        @Override
+        public String greetingMessage(EvaluationContext ctx) {
+            return client.getStringValue("greetingMessage", "Hello there!", ctx);
+        }
+
+        @Override
+        public FlagEvaluationDetails<String> greetingMessageDetails(EvaluationContext ctx) {
+            return client.getStringDetails("greetingMessage", "Hello there!", ctx);
+        }
+
+        @Override
+        public Integer usernameMaxLength(EvaluationContext ctx) {
+            return client.getIntegerValue("usernameMaxLength", 50, ctx);
+        }
+
+        @Override
+        public FlagEvaluationDetails<Integer> usernameMaxLengthDetails(EvaluationContext ctx) {
+            return client.getIntegerDetails("usernameMaxLength", 50, ctx);
+        }
+
+    }
+
+    public static GeneratedClient getClient() {
+        return new OpenFeatureGeneratedClient(OpenFeatureAPI.getInstance().getClient());
+    }
+
+    public static GeneratedClient getClient(String domain) {
+        return new OpenFeatureGeneratedClient(OpenFeatureAPI.getInstance().getClient(domain));
+    }
+}

docs/commands/openfeature_generate.md

@@ -28,6 +28,7 @@ openfeature generate [flags]
 * [openfeature](openfeature.md)	 - CLI for OpenFeature.
 * [openfeature generate csharp](openfeature_generate_csharp.md)	 - Generate typesafe C# client.
 * [openfeature generate go](openfeature_generate_go.md)	 - Generate typesafe accessors for OpenFeature.
+* [openfeature generate java](openfeature_generate_java.md)	 - Generate typesafe Java client.
 * [openfeature generate nestjs](openfeature_generate_nestjs.md)	 - Generate typesafe NestJS decorators.
 * [openfeature generate nodejs](openfeature_generate_nodejs.md)	 - Generate typesafe Node.js client.
 * [openfeature generate python](openfeature_generate_python.md)	 - Generate typesafe Python client.

docs/commands/openfeature_generate_java.md

@@ -0,0 +1,37 @@
+<!-- markdownlint-disable-file -->
+<!-- WARNING: THIS DOC IS AUTO-GENERATED. DO NOT EDIT! -->
+## openfeature generate java
+
+Generate typesafe Java client.
+
+
+> **Stability**: alpha
+
+### Synopsis
+
+Generate typesafe Java client compatible with the OpenFeature Java SDK.
+
+```
+openfeature generate java [flags]
+```
+
+### Options
+
+```
+  -h, --help                  help for java
+      --package-name string   Name of the generated Java package (default "com.example.openfeature")
+```
+
+### Options inherited from parent commands
+
+```
+      --debug             Enable debug logging
+  -m, --manifest string   Path to the flag manifest (default "flags.json")
+      --no-input          Disable interactive prompts
+  -o, --output string     Path to where the generated files should be saved
+```
+
+### SEE ALSO
+
+* [openfeature generate](openfeature_generate.md)	 - Generate typesafe OpenFeature accessors.
+

internal/config/flags.go

@@ -13,6 +13,7 @@ const (
 	GoPackageFlagName   = "package-name"
 	CSharpNamespaceName = "namespace"
 	OverrideFlagName    = "override"
+	JavaPackageFlagName = "package-name"
 )
 
 // Default values for flags
@@ -21,6 +22,7 @@ const (
 	DefaultOutputPath      = ""
 	DefaultGoPackageName   = "openfeature"
 	DefaultCSharpNamespace = "OpenFeature"
+	DefaultJavaPackageName = "com.example.openfeature"
 )
 
 // AddRootFlags adds the common flags to the given command
@@ -45,6 +47,11 @@ func AddCSharpGenerateFlags(cmd *cobra.Command) {
 	cmd.Flags().String(CSharpNamespaceName, DefaultCSharpNamespace, "Namespace for the generated C# code")
 }
 
+// AddJavaGenerateFlags adds the Java generator specific flags to the given command
+func AddJavaGenerateFlags(cmd *cobra.Command) {
+	cmd.Flags().String(JavaPackageFlagName, DefaultJavaPackageName, "Name of the generated Java package")
+}
+
 // AddInitFlags adds the init command specific flags
 func AddInitFlags(cmd *cobra.Command) {
 	cmd.Flags().Bool(OverrideFlagName, false, "Override an existing configuration")
@@ -74,6 +81,12 @@ func GetCSharpNamespace(cmd *cobra.Command) string {
 	return namespace
 }
 
+// GetJavaPackageName gets the Java package name from the given command
+func GetJavaPackageName(cmd *cobra.Command) string {
+	javaPackageName, _ := cmd.Flags().GetString(JavaPackageFlagName)
+	return javaPackageName
+}
+
 // GetNoInput gets the no-input flag from the given command
 func GetNoInput(cmd *cobra.Command) bool {
 	noInput, _ := cmd.Flags().GetBool(NoInputFlagName)