Make public and reuse IOUtils.EMPTY_BYTE_ARRAY.

Author: Gary Gregory

src/changes/changes.xml

@@ -169,6 +169,9 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="ggregory" type="add" due-to="Gary Gregory">
         Add and use IOUtils.byteArray(*).
       </action>
+      <action dev="ggregory" type="add" due-to="Gary Gregory">
+        Make public and reuse IOUtils.EMPTY_BYTE_ARRAY.
+      </action>
       <!-- UPDATES -->
       <action dev="ggregory" type="update" due-to="Dependabot">
         Update junit-jupiter from 5.6.2 to 5.7.0 #153.

src/main/java/org/apache/commons/io/IOUtils.java

@@ -105,7 +105,12 @@ public class IOUtils {
     // Writer. Each method should take at least one of these as a parameter,
     // or return one of them.
 
-    private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
+    /** 
+     * A singleton empty byte array.
+     *
+     *  @since 2.9.0
+     */
+    public static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
 
     /**
      * The default buffer size ({@value}) to use in copy methods.

src/main/java/org/apache/commons/io/output/AbstractByteArrayOutputStream.java

@@ -61,9 +61,6 @@ public abstract class AbstractByteArrayOutputStream extends OutputStream {
 
     static final int DEFAULT_SIZE = 1024;
 
-    /** A singleton empty byte array. */
-    private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
-
     /** The list of buffers, which grows and never reduces. */
     private final List<byte[]> buffers = new ArrayList<>();
     /** The index of the current buffer. */
@@ -363,7 +360,7 @@ protected interface InputStreamConstructor<T extends InputStream> {
     protected byte[] toByteArrayImpl() {
         int remaining = count;
         if (remaining == 0) {
-            return EMPTY_BYTE_ARRAY;
+            return IOUtils.EMPTY_BYTE_ARRAY;
         }
         final byte[] newbuf = IOUtils.byteArray(remaining);
         int pos = 0;

src/test/java/org/apache/commons/io/CharsetsTestCase.java

@@ -22,6 +22,7 @@
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.util.SortedMap;
+
 import org.junit.jupiter.api.Test;
 
 /**

src/test/java/org/apache/commons/io/FileUtilsDeleteDirectoryBaseTestCase.java

@@ -22,6 +22,7 @@
 
 import java.io.File;
 import java.nio.file.Files;
+
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 

src/test/java/org/apache/commons/io/file/PathUtilsDeleteFileTest.java

@@ -22,12 +22,14 @@
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assumptions.assumeFalse;
+
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.LinkOption;
 import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+
 import org.apache.commons.io.file.Counters.PathCounters;
 import org.apache.commons.lang3.SystemUtils;
 import org.junit.jupiter.api.AfterEach;

src/test/java/org/apache/commons/io/function/IOFunctionTest.java

@@ -17,7 +17,8 @@
 
 package org.apache.commons.io.function;
 
-import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
@@ -26,8 +27,7 @@
 import java.util.function.Function;
 import java.util.function.Supplier;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
+import org.junit.jupiter.api.Test;
 
 public class IOFunctionTest {
 

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

@@ -68,7 +68,7 @@ public void testReadArray() throws Exception {
         compare("limit = -1", helloWorld, IOUtils.toByteArray(bounded));
 
         bounded = new BoundedInputStream(new ByteArrayInputStream(helloWorld), 0);
-        compare("limit = 0", new byte[0], IOUtils.toByteArray(bounded));
+        compare("limit = 0", IOUtils.EMPTY_BYTE_ARRAY, IOUtils.toByteArray(bounded));
 
         bounded = new BoundedInputStream(new ByteArrayInputStream(helloWorld), helloWorld.length);
         compare("limit = length", helloWorld, IOUtils.toByteArray(bounded));

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

@@ -118,7 +118,7 @@ public void testResetting() throws Exception {
 
     @Test
     public void testZeroLength1() throws Exception {
-        final ByteArrayInputStream bais = new ByteArrayInputStream(new byte[0]);
+        final ByteArrayInputStream bais = new ByteArrayInputStream(IOUtils.EMPTY_BYTE_ARRAY);
         try (final CountingInputStream cis = new CountingInputStream(bais)) {
 
             final int found = cis.read();
@@ -129,7 +129,7 @@ public void testZeroLength1() throws Exception {
 
     @Test
     public void testZeroLength2() throws Exception {
-        final ByteArrayInputStream bais = new ByteArrayInputStream(new byte[0]);
+        final ByteArrayInputStream bais = new ByteArrayInputStream(IOUtils.EMPTY_BYTE_ARRAY);
         try (final CountingInputStream cis = new CountingInputStream(bais)) {
 
             final byte[] result = new byte[10];
@@ -142,7 +142,7 @@ public void testZeroLength2() throws Exception {
 
     @Test
     public void testZeroLength3() throws Exception {
-        final ByteArrayInputStream bais = new ByteArrayInputStream(new byte[0]);
+        final ByteArrayInputStream bais = new ByteArrayInputStream(IOUtils.EMPTY_BYTE_ARRAY);
         try (final CountingInputStream cis = new CountingInputStream(bais)) {
 
             final byte[] result = new byte[10];

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

@@ -16,12 +16,15 @@
  */
 package org.apache.commons.io.input;
 
-import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.io.IOException;
 import java.io.InputStream;
 
-import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.api.Test;
 
 public class MarkShieldInputStreamTest {