diff --git a/AUTHORS b/AUTHORS
index 0b4bdf753..aeda95fcc 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -53,6 +53,7 @@ Isaac Potoczny-Jones
 Ivan Poliakov
 Jacob Haynes (Google)
 Jeff Breidenbach (Google)
+jjYBdx4IL
 Joan Montané (Softcatalà.cat)
 John Connolly (Bug Labs)
 Jonas Petersson (Prisjakt)
diff --git a/core/src/main/java/com/google/zxing/ReaderException.java b/core/src/main/java/com/google/zxing/ReaderException.java
index 871a0d98d..2253d657d 100644
--- a/core/src/main/java/com/google/zxing/ReaderException.java
+++ b/core/src/main/java/com/google/zxing/ReaderException.java
@@ -33,7 +33,7 @@ public abstract class ReaderException extends Exception {
   }
 
   ReaderException(Throwable cause) {
-      super(cause);
+    super(cause);
   }
 
   // Prevent stack traces from being taken
diff --git a/core/src/main/java/com/google/zxing/common/BitMatrix.java b/core/src/main/java/com/google/zxing/common/BitMatrix.java
index c3004a0d0..1a3bba8f4 100755
--- a/core/src/main/java/com/google/zxing/common/BitMatrix.java
+++ b/core/src/main/java/com/google/zxing/common/BitMatrix.java
@@ -63,7 +63,6 @@ public final class BitMatrix implements Cloneable {
   }
 
   public static BitMatrix parse(String stringRepresentation, String setString, String unsetString) {
-    int pos = 0;
     if (stringRepresentation == null) {
       throw new IllegalArgumentException();
     }
@@ -73,8 +72,10 @@ public final class BitMatrix implements Cloneable {
     int rowStartPos = 0;
     int rowLength = -1;
     int nRows = 0;
+    int pos = 0;
     while (pos < stringRepresentation.length()) {
-      if (stringRepresentation.substring(pos, pos + 1).equals("\n") || stringRepresentation.substring(pos, pos + 1).equals("\r")) {
+      if (stringRepresentation.charAt(pos) == '\n' ||
+          stringRepresentation.charAt(pos) == '\r') {
         if (bitsPos > rowStartPos) {
           if(rowLength == -1) {
             rowLength = bitsPos - rowStartPos;
@@ -97,7 +98,8 @@ public final class BitMatrix implements Cloneable {
         bits[bitsPos] = false;
         bitsPos++;
       } else {
-        throw new IllegalArgumentException("illegal character encountered: " + stringRepresentation.substring(pos));
+        throw new IllegalArgumentException(
+            "illegal character encountered: " + stringRepresentation.substring(pos));
       }
     }
 
@@ -105,15 +107,14 @@ public final class BitMatrix implements Cloneable {
     if (bitsPos > rowStartPos) {
       if(rowLength == -1) {
         rowLength = bitsPos - rowStartPos;
-      }
-      else if (bitsPos - rowStartPos != rowLength) {
+      } else if (bitsPos - rowStartPos != rowLength) {
         throw new IllegalArgumentException("row lengths do not match");
       }
       nRows++;
     }
 
     BitMatrix matrix = new BitMatrix(rowLength, nRows);
-    for (int i=0; i<bitsPos; i++) {
+    for (int i = 0; i < bitsPos; i++) {
       if (bits[i]) {
         matrix.set(i % rowLength, i / rowLength);
       }
@@ -161,17 +162,17 @@ public final class BitMatrix implements Cloneable {
   }
 
   /**
-   * <p>XOR for {@link BitMatrix}.</p>
-   * Flip the bit in this {@link BitMatrix} if the corresponding mask bit is set.
+   * Exclusive-or (XOR): Flip the bit in this {@code BitMatrix} if the corresponding
+   * mask bit is set.
    *
-   * @param mask
+   * @param mask XOR mask
    */
   public void xor(BitMatrix mask) {
     if (width != mask.getWidth() || height != mask.getHeight()
         || rowSize != mask.getRowSize()) {
       throw new IllegalArgumentException("input matrix dimensions do not match");
     }
-    BitArray rowArray = new BitArray(width/32+1);
+    BitArray rowArray = new BitArray(width / 32 + 1);
     for (int y = 0; y < height; y++) {
       int offset = y * rowSize;
       int[] row = mask.getRow(y, rowArray).getBitArray();
diff --git a/core/src/test/java/com/google/zxing/aztec/decoder/DecoderTest.java b/core/src/test/java/com/google/zxing/aztec/decoder/DecoderTest.java
index 1babafc13..2df4f202f 100644
--- a/core/src/test/java/com/google/zxing/aztec/decoder/DecoderTest.java
+++ b/core/src/test/java/com/google/zxing/aztec/decoder/DecoderTest.java
@@ -19,11 +19,9 @@ import com.google.zxing.FormatException;
 import com.google.zxing.ResultPoint;
 import com.google.zxing.aztec.AztecDetectorResult;
 import com.google.zxing.common.BitMatrix;
-import com.google.zxing.common.DecoderResult;
 import org.junit.Test;
-import static org.junit.Assert.*;
 
-public class DecoderTest {
+public final class DecoderTest {
 
   private static final ResultPoint[] NO_POINTS = new ResultPoint[0];
 
@@ -36,8 +34,8 @@ public class DecoderTest {
    *	at com.google.zxing.aztec.decoder.Decoder.decode(Decoder.java:77)
    *	at com.google.zxing.aztec.decoder.DecoderTest.testDecodeBug1(DecoderTest.java:66)</pre>
    */
-  @Test
-  public void testDecodeTooManyErrors() {
+  @Test(expected = FormatException.class)
+  public void testDecodeTooManyErrors() throws FormatException {
     BitMatrix matrix = BitMatrix.parse(""
         + "X X . X . . . X X . . . X . . X X X . X . X X X X X . \n"
         + "X X . . X X . . . . . X X . . . X X . . . X . X . . X \n"
@@ -68,15 +66,11 @@ public class DecoderTest {
         + "X X . X . X . . . X . X . . . . X X . X . . X X . . . \n",
         "X ", ". ");
     AztecDetectorResult r = new AztecDetectorResult(matrix, NO_POINTS, true, 16, 4);
-    try {
-      DecoderResult res = new Decoder().decode(r);
-      fail();
-    } catch (FormatException ex) {
-    }
+    new Decoder().decode(r);
   }
 
-  @Test
-  public void testDecodeTooManyErrors2() {
+  @Test(expected = FormatException.class)
+  public void testDecodeTooManyErrors2() throws FormatException {
     BitMatrix matrix = BitMatrix.parse(""
         + ". X X . . X . X X . . . X . . X X X . . . X X . X X . \n"
         + "X X . X X . . X . . . X X . . . X X . X X X . X . X X \n"
@@ -107,11 +101,7 @@ public class DecoderTest {
         + "X X . . . X X . . X . X . . . . X X . X . . X . X . X \n",
         "X ", ". ");
     AztecDetectorResult r = new AztecDetectorResult(matrix, NO_POINTS, true, 16, 4);
-    try {
-      DecoderResult res = new Decoder().decode(r);
-      fail();
-    } catch (FormatException ex) {
-    }
+    new Decoder().decode(r);
   }
 
 }
diff --git a/core/src/test/java/com/google/zxing/aztec/encoder/EncoderTest.java b/core/src/test/java/com/google/zxing/aztec/encoder/EncoderTest.java
index aaf45e2ae..5331ad14b 100644
--- a/core/src/test/java/com/google/zxing/aztec/encoder/EncoderTest.java
+++ b/core/src/test/java/com/google/zxing/aztec/encoder/EncoderTest.java
@@ -27,17 +27,14 @@ import com.google.zxing.common.BitArray;
 import com.google.zxing.common.BitMatrix;
 import com.google.zxing.common.DecoderResult;
 import org.junit.Assert;
-import org.junit.Ignore;
 import org.junit.Test;
 
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
-import java.security.SecureRandom;
 import java.util.EnumMap;
 import java.util.Map;
 import java.util.Random;
 import java.util.regex.Pattern;
-import org.junit.Before;
 
 /**
  * Aztec 2D generator unit tests.
@@ -49,12 +46,6 @@ public final class EncoderTest extends Assert {
 
   private static final Pattern DOTX = Pattern.compile("[^.X]");
   private static final ResultPoint[] NO_POINTS = new ResultPoint[0];
-  private static Random random;
-
-  @Before
-  public void beforeTest() {
-    random = new Random(0);
-  }
 
   // real life tests
 
@@ -513,7 +504,7 @@ public final class EncoderTest extends Assert {
   }
 
   private static Random getPseudoRandom() {
-    return random;
+    return new Random(0xDEADBEEF);
   }
 
   private static void testModeMessage(boolean compact, int layers, int words, String expected) {
diff --git a/core/src/test/java/com/google/zxing/common/BitArrayTestCase.java b/core/src/test/java/com/google/zxing/common/BitArrayTestCase.java
index 872188c09..e86406dd9 100644
--- a/core/src/test/java/com/google/zxing/common/BitArrayTestCase.java
+++ b/core/src/test/java/com/google/zxing/common/BitArrayTestCase.java
@@ -101,7 +101,7 @@ public final class BitArrayTestCase extends Assert {
   
   @Test
   public void testGetNextSet5() {
-    Random r = new SecureRandom(new byte[] {(byte) 0xDE, (byte) 0xAD, (byte) 0xBE, (byte) 0xEF});
+    Random r = new Random(0xDEADBEEF);
     for (int i = 0; i < 10; i++) {
       BitArray array = new BitArray(1 + r.nextInt(100));
       int numSet = r.nextInt(20);
diff --git a/core/src/test/java/com/google/zxing/common/BitMatrixTestCase.java b/core/src/test/java/com/google/zxing/common/BitMatrixTestCase.java
index 60cd3f93b..0b43278b2 100644
--- a/core/src/test/java/com/google/zxing/common/BitMatrixTestCase.java
+++ b/core/src/test/java/com/google/zxing/common/BitMatrixTestCase.java
@@ -173,7 +173,9 @@ public final class BitMatrixTestCase extends Assert {
     try {
       assertEquals(centerMatrix, BitMatrix.parse("   \n xy\n   \n", "x", " "));
       fail();
-    } catch (IllegalArgumentException ex) {}
+    } catch (IllegalArgumentException ex) {
+      // good
+    }
 
     assertEquals(emptyMatrix24, BitMatrix.parse("  \n  \n  \n  \n", "x", " "));
 
@@ -222,12 +224,16 @@ public final class BitMatrixTestCase extends Assert {
     try {
       emptyMatrix.clone().xor(badMatrix);
       fail();
-    } catch(IllegalArgumentException ex) {}
+    } catch(IllegalArgumentException ex) {
+      // good
+    }
 
     try {
       badMatrix.clone().xor(emptyMatrix);
       fail();
-    } catch(IllegalArgumentException ex) {}
+    } catch(IllegalArgumentException ex) {
+      // good
+    }
   }
 
   private static void testXOR(BitMatrix dataMatrix, BitMatrix flipMatrix, BitMatrix expectedMatrix) {
diff --git a/core/src/test/java/com/google/zxing/common/reedsolomon/ReedSolomonTestCase.java b/core/src/test/java/com/google/zxing/common/reedsolomon/ReedSolomonTestCase.java
index f86d35efa..0e85564dd 100644
--- a/core/src/test/java/com/google/zxing/common/reedsolomon/ReedSolomonTestCase.java
+++ b/core/src/test/java/com/google/zxing/common/reedsolomon/ReedSolomonTestCase.java
@@ -501,7 +501,7 @@ public final class ReedSolomonTestCase extends Assert {
   }
 
   private static Random getPseudoRandom() {
-    return new SecureRandom(new byte[] {(byte) 0xDE, (byte) 0xAD, (byte) 0xBE, (byte) 0xEF});
+    return new Random(0xDEADBEEF);
   }
 
 }
\ No newline at end of file
diff --git a/core/src/test/java/com/google/zxing/pdf417/decoder/ec/AbstractErrorCorrectionTestCase.java b/core/src/test/java/com/google/zxing/pdf417/decoder/ec/AbstractErrorCorrectionTestCase.java
index 06d7221c4..b017f6130 100644
--- a/core/src/test/java/com/google/zxing/pdf417/decoder/ec/AbstractErrorCorrectionTestCase.java
+++ b/core/src/test/java/com/google/zxing/pdf417/decoder/ec/AbstractErrorCorrectionTestCase.java
@@ -49,7 +49,7 @@ abstract class AbstractErrorCorrectionTestCase extends Assert {
   }
 
   static Random getRandom() {
-    return new Random(0);
+    return new Random(0xDEADBEEF);
   }
 
 }
\ No newline at end of file