Handle user dismissal of input box in notebook instead of closing input stream

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;
     }
 }

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