Fix NullPointer exceptions in SemanticPropsUtil

stratosphere-java/src/main/java/eu/stratosphere/api/java/functions/SemanticPropUtil.java

@@ -80,9 +80,11 @@ public class SemanticPropUtil {
 			return;
 		}
 		for (String s : cf) {
+			if (s != null) {
 				readConstantSet(sm, s, inType, outType, 0);
 			}
 		}
+	}
 
 	private static void readConstantSet(SemanticProperties sp, String s, TypeInformation<?> inType, TypeInformation<?> outType, int input) {
 		if (s.equals("*")) {
@@ -150,9 +152,11 @@ public class SemanticPropUtil {
 		}
 
 		for (String s : cff) {
+			if (s != null) {
 				readConstantSet(dm, s, inType, outType, 0);
 			}
 		}
+	}
 
 	private static void parseConstantFieldsSecond(String[] cfs, DualInputSemanticProperties dm, TypeInformation<?> inType, TypeInformation<?> outType) {
 		if (cfs == null) {
@@ -160,9 +164,11 @@ public class SemanticPropUtil {
 		}
 		
 		for (String s : cfs) {
+			if (s != null) {
 				readConstantSet(dm, s, inType, outType, 1);
 			}
 		}
+	}
 
 	private static void parseConstantFieldsFirstExcept(String[] cffe, DualInputSemanticProperties dm, TypeInformation<?> inType, TypeInformation<?> outType) {
 		if (cffe == null) {
@@ -170,6 +176,10 @@ public class SemanticPropUtil {
 		}
 
 		for (String str : cffe) {
+			if (str == null) {
+				continue;
+			}
+			
 			FieldSet fs = readFieldSetFromString(str, inType, outType);
 	
 			for (int i = 0; i < outType.getArity(); i++) {
@@ -186,6 +196,10 @@ public class SemanticPropUtil {
 		}
 
 		for (String str : cfse) {
+			if (str == null) {
+				continue;
+			}
+			
 			FieldSet fs = readFieldSetFromString(str, inType, outType);
 	
 			for (int i = 0; i < outType.getArity(); i++) {
@@ -202,10 +216,12 @@ public class SemanticPropUtil {
 		}
 
 		for (String str : rf) {
+			if (str != null) {
 				FieldSet fs = readFieldSetFromString(str, inType, outType);
 				dm.addReadFields1(fs);
 			}
 		}
+	}
 
 	private static void parseReadFieldsSecond(String[] rf, DualInputSemanticProperties dm, TypeInformation<?> inType, TypeInformation<?> outType) {
 		if (rf == null) {
@@ -213,10 +229,12 @@ public class SemanticPropUtil {
 		}
 
 		for (String str : rf) {
+			if (str != null) {
 				FieldSet fs = readFieldSetFromString(str, inType, outType);
 				dm.addReadFields2(fs);
 			}
 		}
+	}
 
 
 	private static boolean isValidField(TypeInformation<?> type, int field) {
@@ -229,6 +247,7 @@ public class SemanticPropUtil {
 		}
 
 		for (String str : cfe) {
+			if (str != null) {
 				FieldSet fs = readFieldSetFromString(str, inType, outType);
 		
 				for (int i = 0; i < outType.getArity(); i++) {
@@ -238,6 +257,7 @@ public class SemanticPropUtil {
 				}
 			}
 		}
+	}
 
 	private static FieldSet readFieldSetFromString(String s, TypeInformation<?> inType, TypeInformation<?> outType) {
 		Matcher matcher = FIELD_SET_CHECK_PATTERN.matcher(s);
@@ -265,10 +285,12 @@ public class SemanticPropUtil {
 		}
 
 		for (String str : rf) {
+			if (str != null) {
 				FieldSet fs = readFieldSetFromString(str, inType, outType);
 				sm.addReadFields(fs);
 			}
 		}
+	}
 
 	public static SingleInputSemanticProperties getSemanticPropsSingleFromString(String[] constantSet, String[] constantSetExcept, String[] readSet, TypeInformation<?> inType, TypeInformation<?> outType) {
 		SingleInputSemanticProperties result = new SingleInputSemanticProperties();