PDFBOX-5660: optimize, as suggested by Valery Bokov; closes #253

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1928453 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

pdfbox/src/main/java/org/apache/pdfbox/pdmodel/font/PDTrueTypeFontEmbedder.java

@@ -23,6 +23,8 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
+
 import org.apache.fontbox.ttf.HorizontalMetricsTable;
 import org.apache.fontbox.ttf.TrueTypeFont;
 import org.apache.pdfbox.cos.COSArray;
@@ -79,9 +81,9 @@ private void setWidths(COSDictionary font, GlyphList glyphList) throws IOExcepti
         HorizontalMetricsTable hmtx = ttf.getHorizontalMetrics();
 
         Map<Integer, String> codeToName = getFontEncoding().getCodeToNameMap();
-
-        int firstChar = Collections.min(codeToName.keySet());
-        int lastChar = Collections.max(codeToName.keySet());
+        Set<Integer> codes = codeToName.keySet();
+        int firstChar = Collections.min(codes);
+        int lastChar = Collections.max(codes);
 
         List<Integer> widths = new ArrayList<>(lastChar - firstChar + 1);
         for (int i = 0; i < lastChar - firstChar + 1; i++)