diff --git a/src/schule/ngb/zm/charts/LineChart.java b/src/schule/ngb/zm/charts/LineChart.java
index 94fcfa1..633e0fe 100644
--- a/src/schule/ngb/zm/charts/LineChart.java
+++ b/src/schule/ngb/zm/charts/LineChart.java
@@ -1,30 +1,19 @@
 package schule.ngb.zm.charts;
 
 import schule.ngb.zm.shapes.Rectangle;
+import schule.ngb.zm.util.Validator;
 
 import java.awt.BasicStroke;
 import java.awt.Graphics2D;
 import java.awt.geom.AffineTransform;
 import java.util.Collection;
+import java.util.NoSuchElementException;
 import java.util.SortedMap;
 import java.util.TreeMap;
 
 public class LineChart extends Rectangle {
 
-	private class LineChartValue {
-
-		double x;
-
-		double value;
-
-		public LineChartValue( double x, double value ) {
-			this.x = x;
-			this.value = value;
-		}
-
-	}
-
-	protected SortedMap<Double, LineChartValue> values;
+	protected SortedMap<Double, ChartValue> values;
 
 	protected boolean drawLines = true;
 
@@ -35,7 +24,7 @@ public class LineChart extends Rectangle {
 	public LineChart( double x, double y, double width, double height, double[] pCoordinates, double[] pValues ) {
 		super(x, y, width, height);
 
-		this.values = new TreeMap<Double, LineChartValue>();
+		this.values = new TreeMap<>();
 		if( pCoordinates != null || pValues != null ) {
 			if( pCoordinates == null ) {
 				pCoordinates = new double[0];
@@ -56,7 +45,7 @@ public class LineChart extends Rectangle {
 	}
 
 	public void addValue( double pCoordinate, double pValue ) {
-		values.put(pCoordinate, new LineChartValue(pCoordinate, pValue));
+		values.put(pCoordinate, new BasicChartValue(pCoordinate, pValue));
 	}
 
 	public void removeValue( double x ) {
@@ -64,11 +53,19 @@ public class LineChart extends Rectangle {
 	}
 
 	public double getValue( double x ) {
-		return values.get(x).value;
+		ChartValue value = values.get(x);
+		if( value == null )
+			throw new NoSuchElementException(String.format("No chart value for x-value <%f> found.", x));
+		return value.getValue();
 	}
 
 	public void setValue( double x, double pValue ) {
-		values.get(x).value = pValue;
+		ChartValue value = values.get(x);
+		if( value != null ) {
+			value.setValue(pValue);
+		} else {
+			this.addValue(x, pValue);
+		}
 	}
 
 	@Override
@@ -76,10 +73,10 @@ public class LineChart extends Rectangle {
 		double xMax = values.lastKey();
 		double yMax = Double.MIN_VALUE;
 
-		Collection<LineChartValue> val = values.values();
-		for( LineChartValue lcv : val ) {
-			if( lcv.value > yMax ) {
-				yMax = lcv.value;
+		Collection<ChartValue> val = values.values();
+		for( ChartValue lcv : val ) {
+			if( lcv.getValue() > yMax ) {
+				yMax = lcv.getValue();
 			}
 		}
 
@@ -91,12 +88,12 @@ public class LineChart extends Rectangle {
 
 		drawAxes(graphics, xUnit, yUnit);
 
-		LineChartValue lastLcv = null;
-		for( LineChartValue lcv : val ) {
+		ChartValue lastLcv = null;
+		for( ChartValue lcv : val ) {
 			if( drawLines && lastLcv != null ) {
 				graphics.setColor(getStrokeColor().getJavaColor());
 				graphics.setStroke(createStroke());
-				graphics.drawLine((int)(lastLcv.x*xUnit), (int)(height - lastLcv.value*yUnit), (int)(lcv.x*xUnit), (int)(height - lcv.value*yUnit));
+				graphics.drawLine((int)(lastLcv.getX()*xUnit), (int)(height - lastLcv.getValue()*yUnit), (int)(lcv.getX()*xUnit), (int)(height - lcv.getValue()*yUnit));
 				drawDot(graphics, lastLcv, xUnit, yUnit);
 			}
 
@@ -107,10 +104,10 @@ public class LineChart extends Rectangle {
 		graphics.setTransform(originalTransform);
 	}
 
-	private void drawDot( Graphics2D graphics, LineChartValue lcv, double xUnit, double yUnit ) {
+	private void drawDot( Graphics2D graphics, ChartValue lcv, double xUnit, double yUnit ) {
 		int dotSize = (int) round(strokeWeight * 2);
 		graphics.setColor(getFillColor().getJavaColor());
-		graphics.fillRect((int)(lcv.x*xUnit - dotSize), (int)(height - lcv.value*yUnit - dotSize), dotSize+dotSize, dotSize+dotSize);
+		graphics.fillRect((int)(lcv.getX()*xUnit - dotSize), (int)(height - lcv.getValue()*yUnit - dotSize), dotSize+dotSize, dotSize+dotSize);
 	}
 
 	private void drawAxes( Graphics2D graphics, double xUnit, double yUnit ) {