--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/common/AbstractResultType.java	Thu Apr 12 19:15:42 2018 +0200
@@ -0,0 +1,104 @@
+/** Copyright (C) 2017 by Bundesanstalt für Gewässerkunde
+ * Software engineering by
+ *  Björnsen Beratende Ingenieure GmbH
+ *  Dr. Schumacher Ingenieurbüro für Wasser und Umwelt
+ *
+ * This file is Free Software under the GNU AGPL (>=v3)
+ * and comes with ABSOLUTELY NO WARRANTY! Check out the
+ * documentation coming with Dive4Elements River for details.
+ */
+package org.dive4elements.river.artifacts.common;
+
+import java.text.NumberFormat;
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
+
+import org.apache.commons.lang.StringUtils;
+import org.dive4elements.artifacts.CallContext;
+import org.dive4elements.artifacts.CallMeta;
+import org.dive4elements.river.artifacts.resources.Resources;
+
+/**
+ * @author Domenico Nardi Tironi
+ */
+public abstract class AbstractResultType implements IResultType {
+
+    /* Cache for formatters because Formatter will always create new formats (which is very expensive) */
+    private final Map<Locale, NumberFormat> formatters = new HashMap<>();
+
+    private final String unit;
+
+    private final String csvHeader;
+
+    private final String pdfHeader;
+
+    protected AbstractResultType(final String unit, final String csvHeader, final String pdfHeader) {
+        this.unit = unit;
+        this.csvHeader = csvHeader;
+        this.pdfHeader = pdfHeader;
+
+    }
+
+    @Override
+    public abstract String exportValue(final CallContext context, final Object value);
+
+    protected final String exportStringValue(final Object value) {
+
+        if (value == null)
+            return StringUtils.EMPTY;
+
+        if (!(value instanceof String))
+            throw new IllegalStateException();
+
+        return (String) value;
+    }
+
+    @Override
+    public final double asDouble(final Object value) {
+        if (value == null)
+            return Double.NaN;
+
+        if (!(value instanceof Number))
+            throw new IllegalStateException();
+
+        final Number number = (Number) value;
+        return number.doubleValue();
+    }
+
+    protected final String exportDoubleValue(final CallContext context, final double value) {
+        if (Double.isNaN(value))
+            return StringUtils.EMPTY;
+
+        final NumberFormat formatter = getFormatter(context);
+        return formatter.format(value);
+    }
+
+    private NumberFormat getFormatter(final CallContext context) {
+        final CallMeta meta = context.getMeta();
+        final Locale locale = Resources.getLocale(meta);
+
+        if (!this.formatters.containsKey(locale))
+            this.formatters.put(locale, createFormatter(context));
+
+        return this.formatters.get(locale);
+    }
+
+    protected abstract NumberFormat createFormatter(CallContext context);
+
+    public final String getCsvHeader() {
+        return this.csvHeader;
+    }
+
+    public final String getCsvHeader(final CallMeta meta) {
+        return Resources.getMsg(meta, this.csvHeader, this.csvHeader);
+    }
+
+    public final String getPdfHeader(final CallMeta meta) {
+        return Resources.getMsg(meta, this.pdfHeader, this.pdfHeader);
+    }
+
+    public final String getUnit() {
+        return this.unit;
+    }
+}
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