diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/ParametricRuleViolation.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/ParametricRuleViolation.java
index 1e8e4c68f5..2936a05b78 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/ParametricRuleViolation.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/ParametricRuleViolation.java
@@ -79,7 +79,7 @@ public class ParametricRuleViolation<T extends Node> implements RuleViolation {
 
     protected String expandVariables(String message) {
 
-        if (message.indexOf("${") < 0) {
+        if (!message.contains("${")) {
             return message;
         }
 
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/util/database/SourceObject.java b/pmd-core/src/main/java/net/sourceforge/pmd/util/database/SourceObject.java
index 5f73974de8..3c9135fec9 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/util/database/SourceObject.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/util/database/SourceObject.java
@@ -131,21 +131,21 @@ public class SourceObject {
         LOG.entering(CLASS_NAME, "getSuffixFromType", this);
         if (null == type || type.isEmpty()) {
             return "";
-        } else if (type.toUpperCase(Locale.ROOT).indexOf("JAVA") >= 0) {
+        } else if (type.toUpperCase(Locale.ROOT).contains("JAVA")) {
             return ".java";
-        } else if (type.toUpperCase(Locale.ROOT).indexOf("TRIGGER") >= 0) {
+        } else if (type.toUpperCase(Locale.ROOT).contains("TRIGGER")) {
             return ".trg";
-        } else if (type.toUpperCase(Locale.ROOT).indexOf("FUNCTION") >= 0) {
+        } else if (type.toUpperCase(Locale.ROOT).contains("FUNCTION")) {
             return ".fnc";
-        } else if (type.toUpperCase(Locale.ROOT).indexOf("PROCEDURE") >= 0) {
+        } else if (type.toUpperCase(Locale.ROOT).contains("PROCEDURE")) {
             return ".prc";
-        } else if (type.toUpperCase(Locale.ROOT).indexOf("PACKAGE_BODY") >= 0) {
+        } else if (type.toUpperCase(Locale.ROOT).contains("PACKAGE_BODY")) {
             return ".pkb";
-        } else if (type.toUpperCase(Locale.ROOT).indexOf("PACKAGE") >= 0) {
+        } else if (type.toUpperCase(Locale.ROOT).contains("PACKAGE")) {
             return ".pks";
-        } else if (type.toUpperCase(Locale.ROOT).indexOf("TYPE_BODY") >= 0) {
+        } else if (type.toUpperCase(Locale.ROOT).contains("TYPE_BODY")) {
             return ".tpb";
-        } else if (type.toUpperCase(Locale.ROOT).indexOf("TYPE") >= 0) {
+        } else if (type.toUpperCase(Locale.ROOT).contains("TYPE")) {
             return ".tps";
         } else {
             return "";
diff --git a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/AbstractPoorMethodCall.java b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/AbstractPoorMethodCall.java
index 32321dc766..b869265b19 100644
--- a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/AbstractPoorMethodCall.java
+++ b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/AbstractPoorMethodCall.java
@@ -75,7 +75,7 @@ public abstract class AbstractPoorMethodCall extends AbstractJavaRule {
         String[] methodNames = methodNames();
 
         for (String element : methodNames) {
-            if (methodCall.indexOf(element) != -1) {
+            if (methodCall.contains(element)) {
                 return true;
             }
         }
diff --git a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/bestpractices/JUnitTestsShouldIncludeAssertRule.java b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/bestpractices/JUnitTestsShouldIncludeAssertRule.java
index aac15c9d87..52807c1119 100644
--- a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/bestpractices/JUnitTestsShouldIncludeAssertRule.java
+++ b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/bestpractices/JUnitTestsShouldIncludeAssertRule.java
@@ -210,7 +210,7 @@ public class JUnitTestsShouldIncludeAssertRule extends AbstractJUnitRule {
                 Node name = pe.getFirstDescendantOfType(ASTName.class);
                 if (name != null) {
                     String img = name.getImage();
-                    if (img.indexOf(".") == -1) {
+                    if (!img.contains(".")) {
                         return false;
                     }
                     String[] tokens = img.split("\\.");
diff --git a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/design/PositionalIteratorRule.java b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/design/PositionalIteratorRule.java
index 945f95f8b9..c5b4a4b461 100644
--- a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/design/PositionalIteratorRule.java
+++ b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/design/PositionalIteratorRule.java
@@ -18,14 +18,14 @@ public class PositionalIteratorRule extends AbstractJavaRule {
     public Object visit(ASTWhileStatement node, Object data) {
         if (hasNameAsChild(node.getChild(0))) {
             String exprName = getName(node.getChild(0));
-            if (exprName.indexOf(".hasNext") != -1 && node.getNumChildren() > 1) {
+            if (exprName.contains(".hasNext") && node.getNumChildren() > 1) {
 
                 Node loopBody = node.getChild(1);
                 List<String> names = new ArrayList<>();
                 collectNames(getVariableName(exprName), names, loopBody);
                 int nextCount = 0;
                 for (String name : names) {
-                    if (name.indexOf(".next") != -1) {
+                    if (name.contains(".next")) {
                         nextCount++;
                     }
                 }
diff --git a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/design/SignatureDeclareThrowsExceptionRule.java b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/design/SignatureDeclareThrowsExceptionRule.java
index 489fb4a8c6..ad4a01a476 100644
--- a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/design/SignatureDeclareThrowsExceptionRule.java
+++ b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/design/SignatureDeclareThrowsExceptionRule.java
@@ -103,7 +103,7 @@ public class SignatureDeclareThrowsExceptionRule extends AbstractJavaRule {
 
     @Override
     public Object visit(ASTImportDeclaration node, Object o) {
-        if (node.getImportedName().indexOf("junit") != -1) {
+        if (node.getImportedName().contains("junit")) {
             junitImported = true;
         }
         return super.visit(node, o);
diff --git a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/performance/InefficientEmptyStringCheckRule.java b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/performance/InefficientEmptyStringCheckRule.java
index f7ae7eeb75..63ad694116 100644
--- a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/performance/InefficientEmptyStringCheckRule.java
+++ b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/performance/InefficientEmptyStringCheckRule.java
@@ -46,7 +46,7 @@ public class InefficientEmptyStringCheckRule extends AbstractInefficientZeroChec
     @Override
     public boolean isTargetMethod(JavaNameOccurrence occ) {
         if (occ.getNameForWhichThisIsAQualifier() != null
-                && occ.getNameForWhichThisIsAQualifier().getImage().indexOf("trim") != -1) {
+                && occ.getNameForWhichThisIsAQualifier().getImage().contains("trim")) {
             Node pExpression = occ.getLocation().getParent().getParent();
             if (pExpression.getNumChildren() > 2 && "length".equals(pExpression.getChild(2).getImage())) {
                 return true;
diff --git a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/performance/InefficientStringBufferingRule.java b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/performance/InefficientStringBufferingRule.java
index cf832d2882..9cf762af10 100644
--- a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/performance/InefficientStringBufferingRule.java
+++ b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/performance/InefficientStringBufferingRule.java
@@ -181,7 +181,7 @@ public class InefficientStringBufferingRule extends AbstractJavaRule {
             return false;
         }
         ASTName n = s.getFirstDescendantOfType(ASTName.class);
-        if (n == null || n.getImage().indexOf(methodName) == -1
+        if (n == null || !n.getImage().contains(methodName)
                 || !(n.getNameDeclaration() instanceof VariableNameDeclaration)) {
             return false;
         }