Add Java language server support

docs/installation.md

@@ -71,6 +71,12 @@ To build Hide from source, follow these steps:
     npm install -g typescript-language-server
     ```
 
+    For Java, install the [Eclipse JDT Language Server](https://projects.eclipse.org/projects/eclipse.jdt.ls). Ensure the `jdtls` binary is available on your `PATH`. For example, using Homebrew:
+
+    ```bash
+    brew install jdtls
+    ```
+
     For Go, install the `gopls` package:
 
     ```bash

docs/quickstart.md

@@ -203,7 +203,7 @@ print(file)
 #129 |     )
 ```
 
-It turns out there was a typo in my patch but Hide noticed it and highlighted the line with the error. Like a normal IDE, Hide runs continuous diagnostics on the code using LSP servers and highlights errors. Currently, Hide provides diagnostics for Python, JavaScript, TypeScript, and Go, and we can add more languages if needed. Let us know in the GitHub Issues if you need support for other languages.
+It turns out there was a typo in my patch but Hide noticed it and highlighted the line with the error. Like a normal IDE, Hide runs continuous diagnostics on the code using LSP servers and highlights errors. Currently, Hide provides diagnostics for Python, Java, JavaScript, TypeScript, and Go, and we can add more languages if needed. Let us know in the GitHub Issues if you need support for other languages.
 
 !!! note
 

openapi.yaml

@@ -412,7 +412,7 @@ components:
           type: array
           items:
             type: string
-            enum: [Go, JavaScript, Python, TypeScript]
+            enum: [Go, Java, JavaScript, Python, TypeScript]
         devcontainer:
           $ref: '#/components/schemas/DevContainerConfig'
 

pkg/lsp/service.go

@@ -22,6 +22,7 @@ type (
 
 var LspServerExecutables = map[LanguageId]Command{
 	Go:         NewCommand("gopls", []string{}),
+	Java:       NewCommand("jdtls", []string{}),
 	Python:     NewCommand("pyright-langserver", []string{"--stdio"}),
 	JavaScript: NewCommand("typescript-language-server", []string{"--stdio"}),
 	TypeScript: NewCommand("typescript-language-server", []string{"--stdio"}),

pkg/lsp/utils.go

@@ -12,6 +12,7 @@ import (
 // For reference see https://github.com/go-enry/go-enry/blob/master/data/languageInfo.go
 const (
 	Go         = LanguageId("Go")
+	Java       = LanguageId("Java")
 	JavaScript = LanguageId("JavaScript")
 	Python     = LanguageId("Python")
 	TypeScript = LanguageId("TypeScript")

pkg/lsp/v2/languages/java_lsp.go

@@ -0,0 +1,66 @@
+package lang
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	protocol "github.com/tliron/glsp/protocol_3_16"
+)
+
+var _ Adapter = (*jdtls)(nil)
+
+type jdtls struct{}
+
+type jdtlsVersion struct {
+	Version string `json:"version"`
+}
+
+func (a *jdtls) Name() ServerName {
+	return "jdtls"
+}
+
+func (a *jdtls) FetchLatestServerVersion(ctx context.Context, delegate Delegate) (interface{}, error) {
+	// jdtls does not expose a simple version endpoint. We rely on the binary
+	// being present on PATH and treat it as "latest".
+	return jdtlsVersion{Version: "latest"}, nil
+}
+
+func (a *jdtls) FetchServerBinary(ctx context.Context, version interface{}, delegate Delegate) (*Binary, error) {
+	path, err := exec.LookPath("jdtls")
+	if err != nil {
+		return nil, fmt.Errorf("jdtls language server not found in PATH: %w", err)
+	}
+
+	dataDir := filepath.Join(delegate.ProjectRootPath(), ".jdtls")
+	if err := os.MkdirAll(dataDir, 0o755); err != nil {
+		return nil, fmt.Errorf("failed to create jdtls data directory: %w", err)
+	}
+
+	return &Binary{
+		Name: a.Name(),
+		Path: path,
+		Arguments: []string{
+			"-data", dataDir,
+		},
+	}, nil
+}
+
+func (a *jdtls) InitializationOptions(ctx context.Context, delegate Delegate) json.RawMessage {
+	return nil
+}
+
+func (a *jdtls) WorkspaceConfiguration(ctx context.Context, delegate Delegate) (json.RawMessage, error) {
+	return nil, nil
+}
+
+func (a *jdtls) CodeActions() ([]protocol.CodeActionKind, error) {
+	return nil, nil
+}
+
+func (a *jdtls) Languages() []LanguageID {
+	return []LanguageID{Java}
+}

pkg/lsp/v2/languages/languages.go

@@ -6,6 +6,7 @@ type LanguageID = string
 // For reference see https://github.com/go-enry/go-enry/blob/master/data/languageInfo.go
 const (
 	Go         LanguageID = "Go"
+	Java       LanguageID = "Java"
 	JavaScript LanguageID = "JavaScript"
 	Python     LanguageID = "Python"
 	TypeScript LanguageID = "TypeScript"
@@ -15,5 +16,5 @@ const (
 )
 
 var Adapters = []Adapter{
-	new(gopls), new(tsserver),
+	new(gopls), new(tsserver), new(jdtls),
 }

pkg/project/manager.go

@@ -28,7 +28,7 @@ const MaxDiagnosticsDelay = time.Second * 1
 type CreateProjectRequest struct {
 	Repository   model.Repository     `json:"repository" validate:"required"`
 	DevContainer *devcontainer.Config `json:"devcontainer,omitempty"`
-	Languages    []lsp.LanguageId     `json:"languages,omitempty" validate:"dive,oneof=Go JavaScript Python TypeScript"`
+	Languages    []lsp.LanguageId     `json:"languages,omitempty" validate:"dive,oneof=Go Java JavaScript Python TypeScript"`
 }
 
 type TaskResult struct {

pkg/project/v2/manager.go

@@ -25,7 +25,7 @@ type Repository struct {
 type CreateProjectRequest struct {
 	Repository   Repository           `json:"repository" validate:"required"`
 	DevContainer *devcontainer.Config `json:"devcontainer,omitempty"`
-	Languages    []lang.LanguageID    `json:"languages,omitempty" validate:"dive,oneof=Go JavaScript Python TypeScript"`
+	Languages    []lang.LanguageID    `json:"languages,omitempty" validate:"dive,oneof=Go Java JavaScript Python TypeScript"`
 }
 
 type Manager interface {