fix: fix the warnings from SpotBugs

build.gradle

@@ -5,6 +5,7 @@ plugins {
     id 'jacoco'
     id 'com.github.kt3k.coveralls' version '2.12.0'
     id "me.champeau.jmh" version "0.6.6"
+    id "com.github.spotbugs" version "5.1.2"
 }
 
 group = 'com.nulab-inc'
@@ -31,6 +32,19 @@ dependencies {
     jmh group: 'org.ow2.asm', name: 'asm', version: '9.3'
 }
 
+spotbugs {
+    ignoreFailures = false
+    effort = 'max'
+    reportLevel = 'high'
+}
+
+spotbugsMain {
+    reports {
+        xml.enabled = false
+        html.enabled = true
+    }
+}
+
 task compileModuleInfoJava(type: JavaCompile, dependsOn: compileJava) {
     classpath = files()
     source = 'src/main/java9/module-info.java'

src/main/java/com/nulabinc/zxcvbn/Scoring.java

@@ -4,6 +4,7 @@
 import com.nulabinc.zxcvbn.matchers.Match;
 import com.nulabinc.zxcvbn.matchers.MatchFactory;
 
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.Calendar;
 import java.util.Collections;
@@ -48,12 +49,7 @@ public Strength mostGuessableMatchSequence(CharSequence password, List<Match> ma
             matchesByJ.get(m.j).add(m);
         }
         for(List<Match> lst : matchesByJ) {
-            Collections.sort(lst, new Comparator<Match>() {
-                @Override
-                public int compare(Match m1, Match m2) {
-                    return m1.i - m2.i;
-                }
-            });
+            Collections.sort(lst, new MatchComparator());
         }
         final Optimal optimal = new Optimal(n);
         for (int k = 0; k < n; k++) {
@@ -162,6 +158,15 @@ private static long factorial(int n) {
         return f;
     }
 
+    private static class MatchComparator implements Comparator<Match>, Serializable {
+        private static final long serialVersionUID = 1L;
+
+        @Override
+        public int compare(Match m1, Match m2) {
+            return m1.i - m2.i;
+        }
+    }
+
     private static class Optimal {
 
         public final List<Map<Integer, Match>> m = new ArrayList<>();

src/main/java/com/nulabinc/zxcvbn/Strength.java

@@ -2,6 +2,7 @@
 
 import com.nulabinc.zxcvbn.matchers.Match;
 
+import java.util.ArrayList;
 import java.util.List;
 
 public class Strength {
@@ -17,6 +18,7 @@ public class Strength {
     private long calcTime;
 
     public Strength() {
+        this.sequence = new ArrayList<>();
     }
 
     public CharSequence getPassword() {

src/main/java/com/nulabinc/zxcvbn/Zxcvbn.java

@@ -6,6 +6,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 
 public class Zxcvbn {
 
@@ -35,7 +36,7 @@ public Strength measure(CharSequence password, List<String> sanitizedInputs) {
         if (sanitizedInputs != null && !sanitizedInputs.isEmpty()) {
             lowerSanitizedInputs = new ArrayList<>(sanitizedInputs.size());
             for (String sanitizedInput : sanitizedInputs) {
-                lowerSanitizedInputs.add(sanitizedInput.toLowerCase());
+                lowerSanitizedInputs.add(sanitizedInput.toLowerCase(Locale.getDefault()));
             }
         } else {
             lowerSanitizedInputs = Collections.emptyList();

src/main/java/com/nulabinc/zxcvbn/io/ClasspathResource.java

@@ -4,7 +4,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 
-public class ClasspathResource implements Resource {
+public final class ClasspathResource implements Resource {
 
     private final String path;
 

src/main/java/com/nulabinc/zxcvbn/matchers/BaseMatcher.java

@@ -4,6 +4,7 @@
 import com.nulabinc.zxcvbn.Matcher;
 import com.nulabinc.zxcvbn.WipeableString;
 
+import java.io.Serializable;
 import java.util.*;
 
 public abstract class BaseMatcher implements Matcher {
@@ -19,17 +20,7 @@ protected Context getContext() {
     }
 
     protected List<Match> sorted(List<Match> matches) {
-        Collections.sort(matches, new Comparator<Match>() {
-            @Override
-            public int compare(Match o1, Match o2) {
-                int c = o1.i - o2.i;
-                if (c != 0) {
-                    return c;
-                } else {
-                    return (o1.j - o2.j);
-                }
-            }
-        });
+        Collections.sort(matches, new MatchComparator());
         return matches;
     }
 
@@ -48,4 +39,18 @@ protected CharSequence translate(CharSequence string, Map<Character, Character>
         return result;
     }
 
+    private static class MatchComparator implements Comparator<Match>, Serializable {
+        private static final long serialVersionUID = 1L;
+
+        @Override
+        public int compare(Match o1, Match o2) {
+            int c = o1.i - o2.i;
+            if (c != 0) {
+                return c;
+            } else {
+                return (o1.j - o2.j);
+            }
+        }
+    }
+
 }

src/main/java/com/nulabinc/zxcvbn/matchers/Keyboard.java

@@ -120,7 +120,7 @@ private Map<Position, String> buildPositionTable(final String layout) {
             final int xUnit = tokenSize + 1;
 
             for (String token : tokens) {
-                assert token.length() == tokenSize : String.format("token [%s] length mismatch:\n%s", token, layout);
+                assert token.length() == tokenSize : String.format("token [%s] length mismatch:%n%s", token, layout);
             }
 
             int y = 1;
@@ -131,7 +131,7 @@ private Map<Position, String> buildPositionTable(final String layout) {
                     int index = line.indexOf(token) - slant;
                     int x = index / xUnit;
                     final int remainder = index % xUnit;
-                    assert remainder == 0 : String.format("unexpected x offset [%d] for %s in:\n%s", x, token, layout);
+                    assert remainder == 0 : String.format("unexpected x offset [%d] for %s in:%n%s", x, token, layout);
                     positionTable.put(Position.of(x, y), token);
                 }