Resolve "NPE in SclUtilities.getAnyLN() if lnInst is null"

Closes #64 (closed)

fr.centralesupelec.edf.riseclipse.iec61850.scl/src/fr/centralesupelec/edf/riseclipse/iec61850/scl/util/SclUtilities.java

@@ -21,6 +21,7 @@
 package fr.centralesupelec.edf.riseclipse.iec61850.scl.util;
 
 import java.util.List;
+import java.util.Objects;
 import java.util.stream.Collectors;
 
 import org.apache.commons.lang3.tuple.Pair;
@@ -59,6 +60,9 @@ public class SclUtilities {
     }
 
     public static Pair< IED, Integer > getIED( @NonNull SCL scl, @NonNull String iedName ) {
+        // protect against NPE
+        if( scl == null ) return Pair.of( null, 0 );
+        
         List< IED > res =
                 scl
                 .getIED()
@@ -73,6 +77,9 @@ public class SclUtilities {
     }
 
     public static Pair< AccessPoint, Integer > getAccessPoint( @NonNull IED ied, @NonNull String apName ) {
+        // protect against NPE
+        if( ied == null ) return Pair.of( null, 0 );
+        
         List< AccessPoint > res =
                 ied
                 .getAccessPoint()
@@ -87,9 +94,11 @@ public class SclUtilities {
     }
 
     public static Pair< LDevice, Integer > getLDevice( @NonNull AccessPoint accessPoint, @NonNull String ldInst ) {
-        if( accessPoint.getServer() == null ) {
-            return Pair.of( null, 0 );
-        }
+        // protect against NPE
+        if( ldInst                  == null ) return Pair.of( null, 0 );
+        if( accessPoint             == null ) return Pair.of( null, 0 );
+        if( accessPoint.getServer() == null ) return Pair.of( null, 0 );
+        
         List< LDevice > res = 
                 accessPoint
                 .getServer()
@@ -105,6 +114,10 @@ public class SclUtilities {
     }
 
     public static Pair< LDevice, Integer > getLDevice( @NonNull IED ied, @NonNull String ldInst ) {
+        // protect against NPE
+        if( ldInst                  == null ) return Pair.of( null, 0 );
+        if( ied                     == null ) return Pair.of( null, 0 );
+        
         List< LDevice > res = 
                 ied
                 .getAccessPoint()
@@ -127,11 +140,16 @@ public class SclUtilities {
         if( "LLN0".equals( lnClass )) {
             return Pair.of( lDevice.getLN0(), ( lDevice.getLN0() == null ) ? 0 : 1  );
         }
+        
+        // Null checks must be done as annotation-based null analysis is not enabled (issue #64)
+        if( lnClass == null ) return Pair.of( null, 0 );
+        if( lnInst == null )  return Pair.of( null, 0 );
+        
         List< LN > res =
                 lDevice
                 .getLN()
                 .stream()
-                .filter( ln ->  lnClass.equals( ln.getLnClass() ) && lnInst.equals( ln.getInst() ) && prefix.equals( ln.getPrefix() ))
+                .filter( ln -> lnClass.equals( ln.getLnClass() ) && lnInst.equals( ln.getInst() ) && Objects.equals( prefix, ln.getPrefix() ))
                 .collect( Collectors.toList() );
         if( res.size() != 1 ) {
             return Pair.of( null, res.size() );