Use Objects.requireNonNull()

Update Javadoc for existing calls.

Author: Gary Gregory

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

@@ -18,6 +18,7 @@
 
 import java.io.Serializable;
 import java.util.Locale;
+import java.util.Objects;
 
 /**
  * Byte Order Mark (BOM) representation - see {@link org.apache.commons.io.input.BOMInputStream}.
@@ -67,28 +68,28 @@ public class ByteOrderMark implements Serializable {
     private final int[] bytes;
 
     /**
-     * Constructs a new BOM.
+     * Constructs a new instance.
      *
      * @param charsetName The name of the charset the BOM represents
      * @param bytes The BOM's bytes
-     * @throws IllegalArgumentException if the charsetName is null or
-     * zero length
-     * @throws IllegalArgumentException if the bytes are null or zero
-     * length
+     * @throws IllegalArgumentException if the charsetName is zero length
+     * @throws IllegalArgumentException if the bytes are zero length
      */
     public ByteOrderMark(final String charsetName, final int... bytes) {
-        if (charsetName == null || charsetName.isEmpty()) {
+        Objects.requireNonNull(charsetName, "charsetName");
+        Objects.requireNonNull(bytes, "bytes");
+        if (charsetName.isEmpty()) {
             throw new IllegalArgumentException("No charsetName specified");
         }
-        if (bytes == null || bytes.length == 0) {
+        if (bytes.length == 0) {
             throw new IllegalArgumentException("No bytes specified");
         }
         this.charsetName = charsetName;
         this.bytes = bytes.clone();
     }
 
     /**
-     * Indicates if this BOM's bytes equals another.
+     * Indicates if this instance's bytes equals another.
      *
      * @param obj The object to compare to
      * @return true if the bom's bytes are equal, otherwise
@@ -99,7 +100,7 @@ public boolean equals(final Object obj) {
         if (!(obj instanceof ByteOrderMark)) {
             return false;
         }
-        final ByteOrderMark bom = (ByteOrderMark)obj;
+        final ByteOrderMark bom = (ByteOrderMark) obj;
         if (bytes.length != bom.length()) {
             return false;
         }
@@ -129,7 +130,7 @@ public int get(final int pos) {
     public byte[] getBytes() {
         final byte[] copy = IOUtils.byteArray(bytes.length);
         for (int i = 0; i < bytes.length; i++) {
-            copy[i] = (byte)bytes[i];
+            copy[i] = (byte) bytes[i];
         }
         return copy;
     }

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

@@ -27,6 +27,7 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
+import java.util.Objects;
 import java.util.StringTokenizer;
 
 /**
@@ -262,25 +263,22 @@ public FileSystemUtils() {
      *  is zero or less
      * @return the amount of free drive space on the drive or volume
      * @throws IllegalArgumentException if the path is invalid
-     * @throws IllegalStateException if an error occurred in initialisation
+     * @throws IllegalStateException if an error occurred in initialization
      * @throws IOException if an error occurs when finding the free space
      */
     long freeSpaceOS(final String path, final int os, final boolean kb, final Duration timeout) throws IOException {
-        if (path == null) {
-            throw new IllegalArgumentException("Path must not be null");
-        }
+        Objects.requireNonNull(path, "path");
         switch (os) {
-            case WINDOWS:
-                return kb ? freeSpaceWindows(path, timeout) / FileUtils.ONE_KB : freeSpaceWindows(path, timeout);
-            case UNIX:
-                return freeSpaceUnix(path, kb, false, timeout);
-            case POSIX_UNIX:
-                return freeSpaceUnix(path, kb, true, timeout);
-            case OTHER:
-                throw new IllegalStateException("Unsupported operating system");
-            default:
-                throw new IllegalStateException(
-                  "Exception caught when determining operating system");
+        case WINDOWS:
+            return kb ? freeSpaceWindows(path, timeout) / FileUtils.ONE_KB : freeSpaceWindows(path, timeout);
+        case UNIX:
+            return freeSpaceUnix(path, kb, false, timeout);
+        case POSIX_UNIX:
+            return freeSpaceUnix(path, kb, true, timeout);
+        case OTHER:
+            throw new IllegalStateException("Unsupported operating system");
+        default:
+            throw new IllegalStateException("Exception caught when determining operating system");
         }
     }
 

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

@@ -19,6 +19,7 @@
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.charset.Charset;
+import java.util.Objects;
 
 /**
  * Dumps data in hexadecimal format.
@@ -74,22 +75,17 @@ public class HexDump {
      *         the data to stream
      * @throws ArrayIndexOutOfBoundsException if the index is
      *         outside the data array's bounds
-     * @throws IllegalArgumentException if the output stream is null
+     * @throws NullPointerException if the output stream is null
      */
-
     public static void dump(final byte[] data, final long offset,
                             final OutputStream stream, final int index)
-            throws IOException, ArrayIndexOutOfBoundsException,
-            IllegalArgumentException {
-
+            throws IOException, ArrayIndexOutOfBoundsException {
+        Objects.requireNonNull(stream, "stream");
         if (index < 0 || index >= data.length) {
             throw new ArrayIndexOutOfBoundsException(
                     "illegal index: " + index + " into array of length "
                     + data.length);
         }
-        if (stream == null) {
-            throw new IllegalArgumentException("cannot write to nullstream");
-        }
         long display_offset = offset + index;
         final StringBuilder buffer = new StringBuilder(74);
 

src/main/java/org/apache/commons/io/comparator/ReverseFileComparator.java

@@ -19,6 +19,7 @@
 import java.io.File;
 import java.io.Serializable;
 import java.util.Comparator;
+import java.util.Objects;
 
 /**
  * Reverses the result of comparing two {@link File} objects using the delegate {@link Comparator}.
@@ -36,10 +37,7 @@ class ReverseFileComparator extends AbstractFileComparator implements Serializab
      * @param delegate The comparator to delegate to.
      */
     public ReverseFileComparator(final Comparator<File> delegate) {
-        if (delegate == null) {
-            throw new IllegalArgumentException("Delegate comparator is missing");
-        }
-        this.delegate = delegate;
+        this.delegate = Objects.requireNonNull(delegate, "delegate");
     }
 
     /**

src/main/java/org/apache/commons/io/filefilter/AbstractFileFilter.java

@@ -39,13 +39,6 @@
  */
 public abstract class AbstractFileFilter implements IOFileFilter, PathVisitor {
 
-    static <T> T requireNonNull(final T obj, final String message) {
-        if (obj == null) {
-            throw new IllegalArgumentException(message);
-        }
-        return obj;
-    }
-
     static FileVisitResult toDefaultFileVisitResult(final boolean accept) {
         return accept ? FileVisitResult.CONTINUE : FileVisitResult.TERMINATE;
     }

src/main/java/org/apache/commons/io/filefilter/DelegateFileFilter.java

@@ -20,6 +20,7 @@
 import java.io.FileFilter;
 import java.io.FilenameFilter;
 import java.io.Serializable;
+import java.util.Objects;
 
 /**
  * This class turns a Java FileFilter or FilenameFilter into an IO FileFilter.
@@ -42,7 +43,7 @@ public class DelegateFileFilter extends AbstractFileFilter implements Serializab
      * @param fileFilter  the filter to decorate
      */
     public DelegateFileFilter(final FileFilter fileFilter) {
-        requireNonNull(fileFilter, "filter");
+        Objects.requireNonNull(fileFilter, "filter");
         this.fileFilter = fileFilter;
         this.filenameFilter = null;
     }
@@ -53,7 +54,7 @@ public DelegateFileFilter(final FileFilter fileFilter) {
      * @param filenameFilter  the filter to decorate
      */
     public DelegateFileFilter(final FilenameFilter filenameFilter) {
-        requireNonNull(filenameFilter, "filter");
+        Objects.requireNonNull(filenameFilter, "filter");
         this.filenameFilter = filenameFilter;
         this.fileFilter = null;
     }

src/main/java/org/apache/commons/io/filefilter/FileFilterUtils.java

@@ -234,15 +234,13 @@ public static IOFileFilter fileFileFilter() {
      *
      * @return a subset of {@code files} that is accepted by the
      *         file filter.
-     * @throws IllegalArgumentException if the filter is {@code null}
+     * @throws NullPointerException if the filter is {@code null}
      *         or {@code files} contains a {@code null} value.
      *
      * @since 2.0
      */
     public static File[] filter(final IOFileFilter filter, final File... files) {
-        if (filter == null) {
-            throw new IllegalArgumentException("file filter is null");
-        }
+        Objects.requireNonNull(filter, "filter");
         if (files == null) {
             return FileUtils.EMPTY_FILE_ARRAY;
         }
@@ -291,15 +289,12 @@ public static File[] filter(final IOFileFilter filter, final Iterable<File> file
      * @param <R> the return type.
      * @param <A> the mutable accumulation type of the reduction operation (often hidden as an implementation detail)
      * @return a subset of files from the stream that is accepted by the filter.
-     * @throws IllegalArgumentException if the filter is {@code null}.
+     * @throws NullPointerException if the filter is {@code null}.
      */
     private static <R, A> R filterFiles(final IOFileFilter filter, final Stream<File> stream,
         final Collector<? super File, A, R> collector) {
-        //Objects.requireNonNull(filter, "filter");
+        Objects.requireNonNull(filter, "filter");
         Objects.requireNonNull(collector, "collector");
-        if (filter == null) {
-            throw new IllegalArgumentException("file filter is null");
-        }
         if (stream == null) {
             return Stream.<File>empty().collect(collector);
         }
@@ -723,20 +718,15 @@ public static IOFileFilter suffixFileFilter(final String suffix, final IOCase io
      *
      * @param filters The file filters
      * @return The list of file filters
-     * @throws IllegalArgumentException if the filters are null or contain a
+     * @throws NullPointerException if the filters are null or contain a
      *         null value.
      * @since 2.0
      */
     public static List<IOFileFilter> toList(final IOFileFilter... filters) {
-        if (filters == null) {
-            throw new IllegalArgumentException("The filters must not be null");
-        }
+        Objects.requireNonNull(filters, "filters");
         final List<IOFileFilter> list = new ArrayList<>(filters.length);
         for (int i = 0; i < filters.length; i++) {
-            if (filters[i] == null) {
-                throw new IllegalArgumentException("The filter[" + i + "] is null");
-            }
-            list.add(filters[i]);
+            list.add(Objects.requireNonNull(filters[i], "filters[i]"));
         }
         return list;
     }

src/main/java/org/apache/commons/io/filefilter/MagicNumberFileFilter.java

@@ -28,6 +28,7 @@
 import java.nio.file.Path;
 import java.nio.file.attribute.BasicFileAttributes;
 import java.util.Arrays;
+import java.util.Objects;
 
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.io.RandomAccessFileMode;
@@ -159,12 +160,12 @@ public MagicNumberFileFilter(final byte[] magicNumber) {
      * @param magicNumbers the magic number to look for in the file.
      * @param offset the byte offset in the file to start comparing bytes.
      *
-     * @throws IllegalArgumentException if {@code magicNumber} is
-     *         {@code null}, or contains no bytes, or {@code offset}
+     * @throws IllegalArgumentException if {@code magicNumber}
+     *         contains no bytes, or {@code offset}
      *         is a negative number.
      */
     public MagicNumberFileFilter(final byte[] magicNumbers, final long offset) {
-        requireNonNull(magicNumbers, "magicNumbers");
+        Objects.requireNonNull(magicNumbers, "magicNumbers");
         if (magicNumbers.length == 0) {
             throw new IllegalArgumentException("The magic number must contain at least one byte");
         }
@@ -218,11 +219,11 @@ public MagicNumberFileFilter(final String magicNumber) {
      * @param offset the byte offset in the file to start comparing bytes.
      *
      * @throws IllegalArgumentException if {@code magicNumber} is
-     *         {@code null} or the empty String, or {@code offset} is
+     *         the empty String, or {@code offset} is
      *         a negative number.
      */
     public MagicNumberFileFilter(final String magicNumber, final long offset) {
-        requireNonNull(magicNumber, "magicNumber");
+        Objects.requireNonNull(magicNumber, "magicNumber");
         if (magicNumber.isEmpty()) {
             throw new IllegalArgumentException("The magic number must contain at least one byte");
         }

src/main/java/org/apache/commons/io/filefilter/NameFileFilter.java

@@ -90,11 +90,11 @@ public NameFileFilter(final List<String> names) {
      *
      * @param names  the names to allow, must not be null
      * @param ioCase  how to handle case sensitivity, null means case-sensitive
-     * @throws IllegalArgumentException if the name list is null
+     * @throws NullPointerException if the name list is null
      * @throws ClassCastException if the list does not contain Strings
      */
     public NameFileFilter(final List<String> names, final IOCase ioCase) {
-        requireNonNull(names, "names");
+        Objects.requireNonNull(names, "names");
         this.names = names.toArray(EMPTY_STRING_ARRAY);
         this.ioCase = toIOCase(ioCase);
     }
@@ -128,12 +128,10 @@ public NameFileFilter(final String... names) {
      *
      * @param name  the name to allow, must not be null
      * @param ioCase  how to handle case sensitivity, null means case-sensitive
-     * @throws IllegalArgumentException if the name is null
+     * @throws NullPointerException if the name is null
      */
     public NameFileFilter(final String name, final IOCase ioCase) {
-        if (name == null) {
-            throw new IllegalArgumentException("The wildcard must not be null");
-        }
+        Objects.requireNonNull(name, "name");
         this.names = new String[] {name};
         this.ioCase = toIOCase(ioCase);
     }
@@ -143,12 +141,10 @@ public NameFileFilter(final String name, final IOCase ioCase) {
      *
      * @param names  the names to allow, must not be null
      * @param ioCase  how to handle case sensitivity, null means case-sensitive
-     * @throws IllegalArgumentException if the names array is null
+     * @throws NullPointerException if the names array is null
      */
     public NameFileFilter(final String[] names, final IOCase ioCase) {
-        if (names == null) {
-            throw new IllegalArgumentException("The array of names must not be null");
-        }
+        Objects.requireNonNull(names, "names");
         this.names = names.clone();
         this.ioCase = toIOCase(ioCase);
     }

src/main/java/org/apache/commons/io/filefilter/NotFileFilter.java

@@ -21,6 +21,7 @@
 import java.nio.file.FileVisitResult;
 import java.nio.file.Path;
 import java.nio.file.attribute.BasicFileAttributes;
+import java.util.Objects;
 
 /**
  * This filter produces a logical NOT of the filters specified.
@@ -39,10 +40,10 @@ public class NotFileFilter extends AbstractFileFilter implements Serializable {
      * Constructs a new file filter that NOTs the result of another filter.
      *
      * @param filter the filter, must not be null
-     * @throws IllegalArgumentException if the filter is null
+     * @throws NullPointerException if the filter is null
      */
     public NotFileFilter(final IOFileFilter filter) {
-        requireNonNull(filter, "filter");
+        Objects.requireNonNull(filter, "filter");
         this.filter = filter;
     }