hexDump to the StringBuilder instead of return String.

Author: js-labs

src/main/java/org/jsl/collider/Util.java

@@ -18,95 +18,91 @@
 package org.jsl.collider;
 
 import java.nio.ByteBuffer;
-import java.util.Arrays;
 
 public class Util
 {
-    private static final char [] HD =
-    {
-        '0', '1', '2', '3', '4', '5', '6', '7',
-        '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
-    };
+    private static final char [] HD = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
 
-    public static String formatDelay( long startTime, long endTime )
+    public static String formatDelay(long startTime, long endTime)
     {
         final long delay = ((endTime - startTime) / 1000);
         if (delay > 0)
-            return String.format( "%d.%06d", delay/1000000, delay%1000000 );
+            return String.format("%d.%06d", delay/1000000, delay%1000000);
         return "0.0";
     }
 
-    public static String hexDump( ByteBuffer bb )
+    public static void hexDump(ByteBuffer byteBuffer, StringBuilder sb, int maxLines)
     {
-        int pos = bb.position();
-        int limit = bb.limit();
+        int pos = byteBuffer.position();
+        int limit = byteBuffer.limit();
         if (pos == limit)
-            return "<empty>";
+        {
+            sb.append("<empty>");
+            return;
+        }
 
-        if (limit > 0xFFFF)
-            limit = 0xFFFF;
+        int c = ((limit - pos) / 16);
+        if (c > maxLines)
+            limit = (pos + (maxLines * 16));
 
-        final StringBuilder sb = new StringBuilder();
-        /*         "0000: 00 01 02 03 04 05 06 07-08 09 0A 0B 0C 0D 0E 0F | ................" */
-        sb.append( "       0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F [" );
-        sb.append( pos );
-        sb.append( ", " );
-        sb.append( limit );
-        sb.append( "]\n" );
-
-        final char [] buf = new char[73];
-        Arrays.fill( buf, ' ' );
-        buf[4] = ':';
-        buf[29] = '-';
-        buf[54] = '|';
-        buf[72] = '\n';
-
-        loop: while (pos < limit)
+        /*        "0000: 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F | ................" */
+        sb.append("       0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F [");
+        sb.append(pos);
+        sb.append(", ");
+        sb.append(limit);
+        sb.append("]\n");
+
+        while (pos < limit)
         {
-            final int pp = (pos - bb.position());
-            buf[0] = HD[(pp >> 12) & 0xF];
-            buf[1] = HD[(pp >> 8) & 0xF];
-            buf[2] = HD[(pp >> 4) & 0xF];
-            buf[3] = HD[pp & 0xF];
-
-            int hp = 6;
-            int cp = 56;
-            for (int idx=0;;)
+            int p = (pos - byteBuffer.position());
+            sb.append(HD[(p >> 12) & 0x0F]);
+            sb.append(HD[(p >> 8) & 0x0F]);
+            sb.append(HD[(p >> 4) & 0x0F]);
+            sb.append(HD[p & 0x0F]);
+            sb.append(": ");
+
+            int n = Math.min((limit - pos), 16);
+            p = pos;
+            for (c=n; c>0; c--, p++)
+            {
+                final int v = (((int)byteBuffer.get(p)) & 0xFF);
+                sb.append(HD[(v >> 4)]);
+                sb.append(HD[v & 0x0F]);
+                sb.append(' ');
+            }
+
+            for (c=(16-n); c>0; c--)
+                sb.append("   ");
+
+            sb.append("| ");
+
+            p = pos;
+            for (c=n; c>0; c--, p++)
             {
-                final int v = bb.get( pos );
-                buf[hp++] = HD[(v >> 4) & 0xF];
-                buf[hp] = HD[v & 0xF];
-                hp+= 2;
-
-                buf[cp++] = ((v >= 32) && (v < 128)) ? (char)v : '.';
-
-                pos++;
-
-                if (++idx == 16)
-                    break;
-
-                if (pos == limit)
-                {
-                    for (; idx<16; idx++)
-                    {
-                        buf[hp++] = ' ';
-                        buf[hp] = ' ';
-                        hp += 2;
-                        buf[cp++] = ' ';
-                    }
-                    sb.append( buf );
-                    break loop;
-                }
+                final int v = byteBuffer.get(p);
+                final char vc = ((v >= 32) ? (char)v : '.');
+                sb.append(vc);
             }
 
-            sb.append( buf );
+            sb.append('\n');
+            pos += n;
         }
+    }
 
+    public static String hexDump(ByteBuffer byteBuffer, int maxLines)
+    {
+        final StringBuilder sb = new StringBuilder();
+        hexDump(byteBuffer, sb, maxLines);
         return sb.toString();
     }
 
-    public static String hexDump( RetainableByteBuffer bb )
+    public static String hexDump(ByteBuffer byteBuffer)
+    {
+        return hexDump(byteBuffer, 10);
+    }
+
+    public static String hexDump(RetainableByteBuffer bb)
     {
-        return hexDump( bb.getNioByteBuffer() );
+        return hexDump(bb.getNioByteBuffer());
     }
 }