ReaderInputStream.Builder.setCharsetEncoder(null) should reset to a

default object, not throw an NPE.

Author: garydgregory

src/changes/changes.xml

@@ -70,6 +70,9 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="ggregory" type="fix" due-to="Shai Shapira, Gary Gregory" issue="IO-798">
         DeferredFileOutputStream throws exception when system temp dir is a symlink.
       </action>
+      <action dev="ggregory" type="fix" due-to="Gary Gregory">
+        ReaderInputStream.Builder.setCharsetEncoder(null) should reset to a default object, not throw an NPE.
+      </action>
       <!-- ADD -->
       <action dev="ggregory" type="add" due-to="Gary Gregory">
         Add CharSequenceInputStream.Builder.

src/main/java/org/apache/commons/io/input/ReaderInputStream.java

@@ -123,6 +123,10 @@ public ReaderInputStream get() throws IOException {
             return new ReaderInputStream(checkOrigin().getReader(getCharset()), charsetEncoder, getBufferSize());
         }
 
+        CharsetEncoder getCharsetEncoder() {
+            return charsetEncoder;
+        }
+
         @Override
         public Builder setCharset(final Charset charset) {
             charsetEncoder = charset.newEncoder();
@@ -132,12 +136,12 @@ public Builder setCharset(final Charset charset) {
         /**
          * Sets the charset encoder.
          *
-         * @param charsetEncoder the charset encoder.
+         * @param charsetEncoder the charset encoder, null resets to a default encoder.
          * @return this
          */
         public Builder setCharsetEncoder(final CharsetEncoder charsetEncoder) {
-            this.charsetEncoder = charsetEncoder;
-            super.setCharset(charsetEncoder.charset());
+            this.charsetEncoder = CharsetEncoders.toCharsetEncoder(charsetEncoder);
+            super.setCharset(this.charsetEncoder.charset());
             return this;
         }
 

src/test/java/org/apache/commons/io/input/ReaderInputStreamTest.java

@@ -18,6 +18,7 @@
 
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -241,6 +242,11 @@ public void testReadZeroEmptyString() throws Exception {
         }
     }
 
+    @Test
+    public void testResetCharsetEncoder() {
+        assertNotNull(ReaderInputStream.builder().setReader(new StringReader("\uD800")).setCharsetEncoder(null).getCharsetEncoder());
+    }
+
     @Test
     public void testUTF16WithSingleByteRead() throws IOException {
         testWithSingleByteRead(TEST_STRING, UTF_16);