diff --git a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/AbstractCompiler.java b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/AbstractCompiler.java
index 2e3da2fc..579e6280 100644
--- a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/AbstractCompiler.java
+++ b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/AbstractCompiler.java
@@ -46,13 +46,13 @@ public abstract class AbstractCompiler
 
     protected static final String PS = System.getProperty( "path.separator" );
 
-    private CompilerOutputStyle compilerOutputStyle;
+    private final CompilerOutputStyle compilerOutputStyle;
 
-    private String inputFileEnding;
+    private final String inputFileEnding;
 
-    private String outputFileEnding;
+    private final String outputFileEnding;
 
-    private String outputFile;
+    private final String outputFile;
 
     // ----------------------------------------------------------------------
     //
@@ -152,7 +152,7 @@ protected static Set<String> getSourceFilesForSourceRoot( CompilerConfiguration
 
         if ( includes != null && !includes.isEmpty() )
         {
-            String[] inclStrs = includes.toArray( new String[includes.size()] );
+            String[] inclStrs = includes.toArray( new String[0] );
             scanner.setIncludes( inclStrs );
         }
         else
@@ -164,7 +164,7 @@ protected static Set<String> getSourceFilesForSourceRoot( CompilerConfiguration
 
         if ( excludes != null && !excludes.isEmpty() )
         {
-            String[] exclStrs = excludes.toArray( new String[excludes.size()] );
+            String[] exclStrs = excludes.toArray( new String[0] );
             scanner.setExcludes( exclStrs );
         }
 
@@ -213,7 +213,7 @@ protected static String[] getSourceFiles( CompilerConfiguration config )
         }
         else
         {
-            result = sources.toArray( new String[sources.size()] );
+            result = sources.toArray( new String[0] );
         }
 
         return result;
diff --git a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/CompilerMessage.java b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/CompilerMessage.java
index 8f9a0048..5ca5a659 100644
--- a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/CompilerMessage.java
+++ b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/CompilerMessage.java
@@ -339,11 +339,8 @@ public enum Kind
          */
         WARNING( "warning" );
 
-        private String type;
-
-        private Kind( final String type )
+        Kind( String type )
         {
-            this.type = type;
         }
     }
 }
diff --git a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/CompilerOutputStyle.java b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/CompilerOutputStyle.java
index c51a734e..f7e0a280 100644
--- a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/CompilerOutputStyle.java
+++ b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/CompilerOutputStyle.java
@@ -57,7 +57,7 @@ public String toString()
 
     public boolean equals( Object other )
     {
-        if ( other == null || !( other instanceof CompilerOutputStyle ) )
+        if ( !( other instanceof CompilerOutputStyle ) )
         {
             return false;
         }
diff --git a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/StreamPumper.java b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/StreamPumper.java
index 5261806d..fc13661d 100644
--- a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/StreamPumper.java
+++ b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/StreamPumper.java
@@ -36,13 +36,13 @@ public class StreamPumper
 {
     private static final int BUFFER_SIZE = 512;
 
-    private BufferedInputStream stream;
+    private final BufferedInputStream stream;
 
     private boolean endOfStream = false;
 
     private int SLEEP_TIME = 5;
 
-    private OutputStream out;
+    private final OutputStream out;
 
     public StreamPumper( BufferedInputStream is, OutputStream out )
     {
diff --git a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/AbstractSourceInclusionScanner.java b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/AbstractSourceInclusionScanner.java
index 02137c17..44af00a8 100644
--- a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/AbstractSourceInclusionScanner.java
+++ b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/AbstractSourceInclusionScanner.java
@@ -56,7 +56,7 @@ protected String[] scanForSources( File sourceDir, Set<String> sourceIncludes, S
         }
         else
         {
-            includes = sourceIncludes.toArray( new String[sourceIncludes.size()] );
+            includes = sourceIncludes.toArray( new String[0] );
         }
 
         ds.setIncludes( includes );
@@ -68,7 +68,7 @@ protected String[] scanForSources( File sourceDir, Set<String> sourceIncludes, S
         }
         else
         {
-            excludes = sourceExcludes.toArray( new String[sourceExcludes.size()] );
+            excludes = sourceExcludes.toArray( new String[0] );
         }
 
         ds.setExcludes( excludes );
diff --git a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/SimpleSourceInclusionScanner.java b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/SimpleSourceInclusionScanner.java
index 967e5672..a420a3a6 100644
--- a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/SimpleSourceInclusionScanner.java
+++ b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/SimpleSourceInclusionScanner.java
@@ -38,9 +38,9 @@
 public class SimpleSourceInclusionScanner
     extends AbstractSourceInclusionScanner
 {
-    private Set<String> sourceIncludes;
+    private final Set<String> sourceIncludes;
 
-    private Set<String> sourceExcludes;
+    private final Set<String> sourceExcludes;
 
     public SimpleSourceInclusionScanner( Set<String> sourceIncludes, Set<String> sourceExcludes )
     {
diff --git a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/StaleSourceScanner.java b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/StaleSourceScanner.java
index dc4f7d7a..d255be5d 100644
--- a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/StaleSourceScanner.java
+++ b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/StaleSourceScanner.java
@@ -42,12 +42,12 @@ public class StaleSourceScanner
 
     public StaleSourceScanner()
     {
-        this( 0, Collections.singleton( "**/*" ), Collections.<String>emptySet() );
+        this( 0, Collections.singleton( "**/*" ), Collections.emptySet() );
     }
 
     public StaleSourceScanner( long lastUpdatedWithinMsecs )
     {
-        this( lastUpdatedWithinMsecs, Collections.singleton( "**/*" ), Collections.<String>emptySet() );
+        this( lastUpdatedWithinMsecs, Collections.singleton( "**/*" ), Collections.emptySet() );
     }
 
     public StaleSourceScanner( long lastUpdatedWithinMsecs, Set<String> sourceIncludes, Set<String> sourceExcludes )
diff --git a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/mapping/SingleTargetSourceMapping.java b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/mapping/SingleTargetSourceMapping.java
index a6273e5b..c68ca279 100644
--- a/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/mapping/SingleTargetSourceMapping.java
+++ b/plexus-compiler-api/src/main/java/org/codehaus/plexus/compiler/util/scan/mapping/SingleTargetSourceMapping.java
@@ -38,9 +38,9 @@
 public class SingleTargetSourceMapping
     implements SourceMapping
 {
-    private String sourceSuffix;
+    private final String sourceSuffix;
 
-    private String outputFile;
+    private final String outputFile;
 
     public SingleTargetSourceMapping( String sourceSuffix, String outputFile )
     {
diff --git a/plexus-compilers/plexus-compiler-javac/src/main/java/org/codehaus/plexus/compiler/javac/JavacCompiler.java b/plexus-compilers/plexus-compiler-javac/src/main/java/org/codehaus/plexus/compiler/javac/JavacCompiler.java
index a0c54090..2a2263d9 100644
--- a/plexus-compilers/plexus-compiler-javac/src/main/java/org/codehaus/plexus/compiler/javac/JavacCompiler.java
+++ b/plexus-compilers/plexus-compiler-javac/src/main/java/org/codehaus/plexus/compiler/javac/JavacCompiler.java
@@ -105,7 +105,7 @@ public class JavacCompiler
 
     private static volatile Class<?> JAVAC_CLASS;
 
-    private List<Class<?>> javaccClasses = new CopyOnWriteArrayList<>();
+    private final List<Class<?>> javaccClasses = new CopyOnWriteArrayList<>();
 
     @Requirement
     private InProcessCompiler inProcessCompiler;
@@ -432,7 +432,7 @@ else if ( !suppressSource( config ) )
             args.add( value );
         }
 
-        return args.toArray( new String[args.size()] );
+        return args.toArray( new String[0] );
     }
 
     /**