From 7afd9570c522fad998d2eb056fde172e894cb7c4 Mon Sep 17 00:00:00 2001
From: Achal Talati <achal.talati@oracle.com>
Date: Fri, 31 Oct 2025 11:47:10 +0530
Subject: [PATCH] Fixed notebook issue when scanner input stream closes itself
 on no input from the user

---
 .../nbcode/java/notebook/CustomInputStream.java      | 12 +++++++++---
 .../nbcode/java/notebook/CustomInputStreamTest.java  |  7 ++++---
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/nbcode/notebooks/src/org/netbeans/modules/nbcode/java/notebook/CustomInputStream.java b/nbcode/notebooks/src/org/netbeans/modules/nbcode/java/notebook/CustomInputStream.java
index 031f5f01..0d5ffd55 100644
--- a/nbcode/notebooks/src/org/netbeans/modules/nbcode/java/notebook/CustomInputStream.java
+++ b/nbcode/notebooks/src/org/netbeans/modules/nbcode/java/notebook/CustomInputStream.java
@@ -16,6 +16,7 @@
 package org.netbeans.modules.nbcode.java.notebook;
 
 import java.io.ByteArrayInputStream;
+import java.io.EOFException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.lang.ref.WeakReference;
@@ -53,14 +54,16 @@ public synchronized int read(byte[] b, int off, int len) throws IOException {
                 NbCodeLanguageClient client = this.client.get();
                 if (client == null) {
                     LOG.log(Level.WARNING, "client is null");
-                    return -1;
+                    throw new EOFException("User input dismissed");
                 }
                 CompletableFuture<String> future = client.showInputBox(new ShowInputBoxParams(USER_PROMPT_REQUEST, "", true));
                 String userInput = future.get();
 
                 if (userInput == null) {
                     LOG.log(Level.WARNING, "User input is null");
-                    return -1;
+                    // Workaround: jshell closes the input stream when -1 is returned and provides no way to reset it.
+                    // This hack bypasses that behavior to prevent the stream from being closed.
+                    throw new EOFException("User input dismissed");
                 }
 
                 byte[] inputBytes = (userInput + System.lineSeparator()).getBytes(StandardCharsets.UTF_8);
@@ -80,6 +83,9 @@ public synchronized int read(byte[] b, int off, int len) throws IOException {
     public int read() throws IOException {
         byte[] oneByte = new byte[1];
         int n = read(oneByte, 0, 1);
-        return (n == -1) ? -1 : oneByte[0] & 0xFF;
+        if (n == -1) {
+            throw new EOFException("User input dismissed");
+        }
+        return oneByte[0] & 0xFF;
     }
 }
diff --git a/nbcode/notebooks/test/unit/src/org/netbeans/modules/nbcode/java/notebook/CustomInputStreamTest.java b/nbcode/notebooks/test/unit/src/org/netbeans/modules/nbcode/java/notebook/CustomInputStreamTest.java
index 23b391d6..b081c07c 100644
--- a/nbcode/notebooks/test/unit/src/org/netbeans/modules/nbcode/java/notebook/CustomInputStreamTest.java
+++ b/nbcode/notebooks/test/unit/src/org/netbeans/modules/nbcode/java/notebook/CustomInputStreamTest.java
@@ -1,10 +1,11 @@
 package org.netbeans.modules.nbcode.java.notebook;
 
+import java.io.EOFException;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.util.concurrent.CompletableFuture;
-import java.util.function.Consumer;
 import org.junit.After;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -33,10 +34,10 @@ public void tearDown() {
     @Test
     public void testReadNoClient() throws IOException {
         inputStream = new CustomInputStream(null);
-        assertEquals(-1, inputStream.read());
+        Assert.assertThrows(EOFException.class, ()-> inputStream.read());            
 
         byte[] buffer = new byte[10];
-        assertEquals(-1, inputStream.read(buffer, 0, 10));
+        Assert.assertThrows(EOFException.class, ()-> inputStream.read(buffer, 0, 10));
     }
 
     @Test