java-decompiler: minor optimization (no more empty array creation)

src/org/jetbrains/java/decompiler/struct/attr/StructLineNumberTableAttribute.java

@@ -17,6 +17,7 @@ package org.jetbrains.java.decompiler.struct.attr;
 
 import org.jetbrains.java.decompiler.struct.consts.ConstantPool;
 import org.jetbrains.java.decompiler.util.DataInputFullStream;
+import org.jetbrains.java.decompiler.util.InterpreterUtil;
 
 import java.io.IOException;
 
@@ -29,7 +30,7 @@ import java.io.IOException;
  * Created by Egor on 05.10.2014.
  */
 public class StructLineNumberTableAttribute extends StructGeneralAttribute {
-  private int[] myLineInfo = new int[0];
+  private int[] myLineInfo = InterpreterUtil.EMPTY_INT_ARRAY;
 
   @Override
   public void initContent(ConstantPool pool) throws IOException {
@@ -44,7 +45,7 @@ public class StructLineNumberTableAttribute extends StructGeneralAttribute {
       }
     }
     else if (myLineInfo.length > 0) {
-      myLineInfo = new int[0];
+      myLineInfo = InterpreterUtil.EMPTY_INT_ARRAY;
     }
   }
 

src/org/jetbrains/java/decompiler/util/FastSparseSetFactory.java

@@ -88,6 +88,7 @@ public class FastSparseSetFactory<E> {
 
 
   public static class FastSparseSet<E> implements Iterable<E> {
+    public static final FastSparseSet[] EMPTY_ARRAY = new FastSparseSet[0];
 
     private FastSparseSetFactory<E> factory;
 

src/org/jetbrains/java/decompiler/util/InterpreterUtil.java

@@ -29,6 +29,8 @@ import java.util.zip.ZipFile;
 public class InterpreterUtil {
   public static final boolean IS_WINDOWS = System.getProperty("os.name", "").startsWith("Windows");
 
+  public static final int[] EMPTY_INT_ARRAY = new int[0];
+
   private static final int CHANNEL_WINDOW_SIZE = IS_WINDOWS ? 64 * 1024 * 1024 - (32 * 1024) : 64 * 1024 * 1024;  // magic number for Windows
   private static final int BUFFER_SIZE = 16 * 1024;
 

src/org/jetbrains/java/decompiler/util/SFormsFastMapDirect.java

@@ -38,9 +38,9 @@ public class SFormsFastMapDirect {
   private SFormsFastMapDirect(boolean initialize) {
     if (initialize) {
       for (int i = 2; i >= 0; i--) {
-        @SuppressWarnings("unchecked") FastSparseSet<Integer>[] empty = new FastSparseSet[0];
+        @SuppressWarnings("unchecked") FastSparseSet<Integer>[] empty = FastSparseSet.EMPTY_ARRAY;
         elements[i] = empty;
-        next[i] = new int[0];
+        next[i] = InterpreterUtil.EMPTY_INT_ARRAY;
       }
     }
   }
@@ -99,8 +99,8 @@ public class SFormsFastMapDirect {
         while (pointer != 0);
       }
       else {
-        mapelements[i] = new FastSparseSet[0];
+        mapelements[i] = FastSparseSet.EMPTY_ARRAY;
-        mapnext[i] = new int[0];
+        mapnext[i] = InterpreterUtil.EMPTY_INT_ARRAY;
       }
     }