diff --git a/java/java-runtime/src/com/intellij/rt/execution/junit/FileComparisonFailure.java b/java/java-runtime/src/com/intellij/rt/execution/junit/FileComparisonFailure.java
index b6b728192713..a540eceacad8 100644
--- a/java/java-runtime/src/com/intellij/rt/execution/junit/FileComparisonFailure.java
+++ b/java/java-runtime/src/com/intellij/rt/execution/junit/FileComparisonFailure.java
@@ -25,12 +25,14 @@ public class FileComparisonFailure extends ComparisonFailure implements KnownExc
   private final String myFilePath;
   private final String myActualFilePath;
 
-  public FileComparisonFailure(String message, String expected, String actual, String filePath) {
-    this(message, expected, actual, filePath, null);
+  public FileComparisonFailure(String message, /*@NotNull */String expected, /*@NotNull */String actual, String expectedFilePath) {
+    this(message, expected, actual, expectedFilePath, null);
   }
 
-  public FileComparisonFailure(String message, String expected, String actual, String expectedFilePath, String actualFilePath) {
+  public FileComparisonFailure(String message, /*@NotNull */String expected, /*@NotNull */String actual, String expectedFilePath, String actualFilePath) {
     super(message, expected, actual);
+    if (expected == null) throw new NullPointerException("'expected' must not be null");
+    if (actual == null) throw new NullPointerException("'actual' must not be null");
     myExpected = expected;
     myActual = actual;
     myFilePath = expectedFilePath;
@@ -60,7 +62,7 @@ public class FileComparisonFailure extends ComparisonFailure implements KnownExc
   private static class MyPacketFactory extends ComparisonDetailsExtractor {
     private final String myFilePath;
 
-    public MyPacketFactory(ComparisonFailure assertion, String expected, String actual, String filePath) {
+    MyPacketFactory(ComparisonFailure assertion, String expected, String actual, String filePath) {
       super(assertion, expected, actual);
       myFilePath = filePath;
     }
diff --git a/platform/platform-tests/testSrc/com/intellij/openapi/editor/EditorPaintingTest.java b/platform/platform-tests/testSrc/com/intellij/openapi/editor/EditorPaintingTest.java
index 72bcca058e93..5e4173fbb4a2 100644
--- a/platform/platform-tests/testSrc/com/intellij/openapi/editor/EditorPaintingTest.java
+++ b/platform/platform-tests/testSrc/com/intellij/openapi/editor/EditorPaintingTest.java
@@ -198,7 +198,7 @@ public class EditorPaintingTest extends AbstractEditorTest {
     }
   }
 
-  private void fail(String message, File expectedResultsFile, BufferedImage actualImage) throws IOException {
+  private void fail(@NotNull String message, @NotNull File expectedResultsFile, BufferedImage actualImage) throws IOException {
     File savedImage = FileUtil.createTempFile(getName(), ".png", false);
     addTmpFileToKeep(savedImage);
     ImageIO.write(actualImage, "png", savedImage);
diff --git a/platform/testFramework/src/com/intellij/testFramework/EditorTestUtil.java b/platform/testFramework/src/com/intellij/testFramework/EditorTestUtil.java
index 33dd5fbb1aa5..5d72a50f04be 100644
--- a/platform/testFramework/src/com/intellij/testFramework/EditorTestUtil.java
+++ b/platform/testFramework/src/com/intellij/testFramework/EditorTestUtil.java
@@ -251,7 +251,8 @@ public class EditorTestUtil {
    *
    * @see #extractCaretAndSelectionMarkers(Document, boolean)
    */
-  public static CaretAndSelectionState extractCaretAndSelectionMarkers(Document document) {
+  @NotNull
+  public static CaretAndSelectionState extractCaretAndSelectionMarkers(@NotNull Document document) {
     return extractCaretAndSelectionMarkers(document, true);
   }
 
@@ -261,7 +262,8 @@ public class EditorTestUtil {
    *
    * @param processBlockSelection if <code>true</code>, &lt;block&gt; and &lt;/block&gt; tags describing a block selection state will also be extracted.
    */
-  public static CaretAndSelectionState extractCaretAndSelectionMarkers(final Document document, final boolean processBlockSelection) {
+  @NotNull
+  public static CaretAndSelectionState extractCaretAndSelectionMarkers(@NotNull Document document, final boolean processBlockSelection) {
     return new WriteCommandAction<CaretAndSelectionState>(null) {
       @Override
       public void run(@NotNull Result<CaretAndSelectionState> actionResult) {
@@ -271,9 +273,8 @@ public class EditorTestUtil {
   }
 
   @NotNull
-  public static CaretAndSelectionState extractCaretAndSelectionMarkersImpl(Document document, boolean processBlockSelection) {
+  public static CaretAndSelectionState extractCaretAndSelectionMarkersImpl(@NotNull Document document, boolean processBlockSelection) {
     List<CaretInfo> carets = ContainerUtil.newArrayList();
-    TextRange blockSelection = null;
     String fileText = document.getText();
 
     RangeMarker blockSelectionStartMarker = null;
@@ -354,6 +355,7 @@ public class EditorTestUtil {
     if (carets.isEmpty()) {
       carets.add(new CaretInfo(null, null));
     }
+    TextRange blockSelection = null;
     if (blockSelectionStartMarker != null) {
       blockSelection = new TextRange(blockSelectionStartMarker.getStartOffset(), blockSelectionEndMarker.getStartOffset());
     }
diff --git a/platform/testFramework/src/com/intellij/testFramework/fixtures/impl/CodeInsightTestFixtureImpl.java b/platform/testFramework/src/com/intellij/testFramework/fixtures/impl/CodeInsightTestFixtureImpl.java
index e96aee74fb41..4423c4b3bdc8 100644
--- a/platform/testFramework/src/com/intellij/testFramework/fixtures/impl/CodeInsightTestFixtureImpl.java
+++ b/platform/testFramework/src/com/intellij/testFramework/fixtures/impl/CodeInsightTestFixtureImpl.java
@@ -1891,6 +1891,7 @@ public class CodeInsightTestFixtureImpl extends BaseFixture implements CodeInsig
 
   private static class SelectionAndCaretMarkupLoader {
     private final String filePath;
+    @NotNull
     private final String newFileText;
     private final EditorTestUtil.CaretAndSelectionState caretState;
 
diff --git a/platform/util/src/com/intellij/openapi/util/io/StreamUtil.java b/platform/util/src/com/intellij/openapi/util/io/StreamUtil.java
index 319191e523dd..83b31097be7f 100644
--- a/platform/util/src/com/intellij/openapi/util/io/StreamUtil.java
+++ b/platform/util/src/com/intellij/openapi/util/io/StreamUtil.java
@@ -25,6 +25,8 @@ import java.io.*;
 import java.nio.charset.Charset;
 
 public class StreamUtil {
+  private static final Logger LOG = Logger.getInstance(StreamUtil.class);
+
   private StreamUtil() {
   }
 
@@ -34,9 +36,8 @@ public class StreamUtil {
    * @param inputStream source stream
    * @param outputStream destination stream
    * @return bytes copied
-   * @throws IOException
    */
-  public static int copyStreamContent(InputStream inputStream, OutputStream outputStream) throws IOException {
+  public static int copyStreamContent(@NotNull InputStream inputStream, @NotNull OutputStream outputStream) throws IOException {
     final byte[] buffer = new byte[10 * 1024];
     int count;
     int total = 0;
@@ -47,7 +48,8 @@ public class StreamUtil {
     return total;
   }
 
-  public static byte[] loadFromStream(InputStream inputStream) throws IOException {
+  @NotNull
+  public static byte[] loadFromStream(@NotNull InputStream inputStream) throws IOException {
     final UnsyncByteArrayOutputStream outputStream = new UnsyncByteArrayOutputStream();
     try {
       copyStreamContent(inputStream, outputStream);
@@ -61,31 +63,37 @@ public class StreamUtil {
   /**
    * @deprecated depends on the default encoding, use StreamUtil#readText(java.io.InputStream, String) instead
    */
-  public static String readText(InputStream inputStream) throws IOException {
+  @NotNull
+  public static String readText(@NotNull InputStream inputStream) throws IOException {
     final byte[] data = loadFromStream(inputStream);
     return new String(data);
   }
 
-  public static String readText(InputStream inputStream, @NotNull String encoding) throws IOException {
+  @NotNull
+  public static String readText(@NotNull InputStream inputStream, @NotNull String encoding) throws IOException {
     final byte[] data = loadFromStream(inputStream);
     return new String(data, encoding);
   }
-  public static String readText(InputStream inputStream, @NotNull Charset encoding) throws IOException {
+  @NotNull
+  public static String readText(@NotNull InputStream inputStream, @NotNull Charset encoding) throws IOException {
     final byte[] data = loadFromStream(inputStream);
     return new String(data, encoding);
   }
 
-  public static String convertSeparators(String s) {
+  @NotNull
+  public static String convertSeparators(@NotNull String s) {
     return StringFactory.createShared(convertSeparators(s.toCharArray()));
   }
 
-  public static char[] readTextAndConvertSeparators(Reader reader) throws IOException {
+  @NotNull
+  public static char[] readTextAndConvertSeparators(@NotNull Reader reader) throws IOException {
     char[] buffer = readText(reader);
 
     return convertSeparators(buffer);
   }
 
-  private static char[] convertSeparators(char[] buffer) {
+  @NotNull
+  private static char[] convertSeparators(@NotNull char[] buffer) {
     int dst = 0;
     char prev = ' ';
     for (char c : buffer) {
@@ -113,11 +121,13 @@ public class StreamUtil {
     return result;
   }
 
-  public static String readTextFrom(Reader reader) throws IOException {
+  @NotNull
+  public static String readTextFrom(@NotNull Reader reader) throws IOException {
     return StringFactory.createShared(readText(reader));
   }
 
-  private static char[] readText(Reader reader) throws IOException {
+  @NotNull
+  private static char[] readText(@NotNull Reader reader) throws IOException {
     CharArrayWriter writer = new CharArrayWriter();
 
     char[] buffer = new char[2048];
@@ -140,7 +150,4 @@ public class StreamUtil {
       }
     }
   }
-
-  private static final Logger LOG = Logger.getInstance(StreamUtil.class);
-
 }