Create app.py

app.py

@@ -0,0 +1,48 @@
+from fastapi import FastAPI, Request
+from fastapi.responses import FileResponse
+from fastapi.middleware.cors import CORSMiddleware
+import subprocess, tempfile, os
+
+app = FastAPI()
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+@app.get("/")
+def serve_frontend():
+    return FileResponse("index.html")
+
+@app.post("/run-java")
+async def run_java(request: Request):
+    data = await request.json()
+    code = data.get("code", "")
+    filename = data.get("filename", "Main.java")
+
+    if not code.strip():
+        return {"output": "❌ No code provided."}
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        filepath = os.path.join(tmpdir, filename)
+        with open(filepath, "w") as f:
+            f.write(code)
+
+        compile_proc = subprocess.run(
+            ["javac", filepath],
+            capture_output=True,
+            text=True
+        )
+        if compile_proc.returncode != 0:
+            return {"output": "Compilation Error:\n" + compile_proc.stderr}
+
+        classname = filename.replace(".java", "")
+        run_proc = subprocess.run(
+            ["java", "-cp", tmpdir, classname],
+            capture_output=True,
+            text=True,
+            timeout=5
+        )
+        return {"output": run_proc.stdout or run_proc.stderr}