diff --git a/testng-core/src/main/java/org/testng/JarFileUtils.java b/testng-core/src/main/java/org/testng/JarFileUtils.java
index 5452dfae72..86ad2fbbbe 100644
--- a/testng-core/src/main/java/org/testng/JarFileUtils.java
+++ b/testng-core/src/main/java/org/testng/JarFileUtils.java
@@ -4,6 +4,7 @@
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.file.Files;
 import java.util.Collection;
 import java.util.Enumeration;
 import java.util.List;
@@ -12,7 +13,6 @@
 import java.util.jar.JarFile;
 import org.testng.collections.Lists;
 import org.testng.internal.Utils;
-import org.testng.reporters.Files;
 import org.testng.util.Strings;
 import org.testng.xml.IPostProcessor;
 import org.testng.xml.XmlSuite;
@@ -76,7 +76,7 @@ private boolean testngXmlExistsInJar(File jarFile, List<String> classes) throws
         if (Parser.canParse(jeName.toLowerCase())) {
           InputStream inputStream = jf.getInputStream(je);
           File copyFile = new File(file, jeName);
-          Files.copyFile(inputStream, copyFile);
+          Files.copy(inputStream, copyFile.toPath());
           if (matchesXmlPathInJar(je)) {
             suitePath = copyFile.toString();
           }
diff --git a/testng-core/src/main/java/org/testng/reporters/Files.java b/testng-core/src/main/java/org/testng/reporters/Files.java
index a4f778e6df..8589b76fbb 100644
--- a/testng-core/src/main/java/org/testng/reporters/Files.java
+++ b/testng-core/src/main/java/org/testng/reporters/Files.java
@@ -14,9 +14,16 @@
 import java.io.StringWriter;
 import java.io.Writer;
 import java.nio.charset.StandardCharsets;
+import java.util.stream.Collectors;
 
-public class Files {
+public final class Files {
 
+  private Files() {
+    // defeat instantiation
+  }
+
+  /** @deprecated - This method stands deprecated as of TestNG <code>7.6.0</code> */
+  @Deprecated
   public static String readFile(File f) throws IOException {
     try (InputStream is = new FileInputStream(f)) {
       return readFile(is);
@@ -24,16 +31,13 @@ public static String readFile(File f) throws IOException {
   }
 
   public static String readFile(InputStream is) throws IOException {
-    StringBuilder result = new StringBuilder();
-    BufferedReader br = new BufferedReader(new InputStreamReader(is));
-    String line = br.readLine();
-    while (line != null) {
-      result.append(line).append("\n");
-      line = br.readLine();
-    }
-    return result.toString();
+    return new BufferedReader(new InputStreamReader(is, StandardCharsets.UTF_8))
+        .lines()
+        .collect(Collectors.joining("\n"));
   }
 
+  /** @deprecated - This method stands deprecated as of TestNG <code>7.6.0</code> */
+  @Deprecated
   public static void writeFile(String string, File f) throws IOException {
     f.getParentFile().mkdirs();
     try (FileWriter fw = new FileWriter(f);
@@ -42,6 +46,8 @@ public static void writeFile(String string, File f) throws IOException {
     }
   }
 
+  /** @deprecated - This method stands deprecated as of TestNG <code>7.6.0</code> */
+  @Deprecated
   public static void copyFile(InputStream from, File to) throws IOException {
     if (!to.getParentFile().exists()) {
       to.getParentFile().mkdirs();
@@ -57,6 +63,8 @@ public static void copyFile(InputStream from, File to) throws IOException {
     }
   }
 
+  /** @deprecated - This method stands deprecated as of TestNG <code>7.6.0</code> */
+  @Deprecated
   public static String streamToString(InputStream is) throws IOException {
     if (is != null) {
       Writer writer = new StringWriter();
diff --git a/testng-core/src/main/java/org/testng/reporters/jq/Main.java b/testng-core/src/main/java/org/testng/reporters/jq/Main.java
index 7af3b0f54a..a020810b97 100644
--- a/testng-core/src/main/java/org/testng/reporters/jq/Main.java
+++ b/testng-core/src/main/java/org/testng/reporters/jq/Main.java
@@ -90,7 +90,7 @@ public void generateReport(
             if (is == null) {
               throw new AssertionError("Couldn't find resource: " + fileName);
             }
-            Files.copyFile(is, new File(outputDirectory, fileName));
+            java.nio.file.Files.copy(is, new File(outputDirectory, fileName).toPath());
           }
         }
         all = Files.readFile(header);
@@ -102,8 +102,7 @@ public void generateReport(
   }
 
   private InputStream load(String fileName) {
-    String path;
-    path = Main.TESTNG_RESOURCE_PREFIX + fileName;
+    String path = Main.TESTNG_RESOURCE_PREFIX + fileName;
     return getClass().getResourceAsStream(path);
   }
 }
diff --git a/testng-core/src/main/java/org/testng/reporters/jq/ResultsByClass.java b/testng-core/src/main/java/org/testng/reporters/jq/ResultsByClass.java
index 81ca29710b..342a1d42bd 100644
--- a/testng-core/src/main/java/org/testng/reporters/jq/ResultsByClass.java
+++ b/testng-core/src/main/java/org/testng/reporters/jq/ResultsByClass.java
@@ -1,6 +1,5 @@
 package org.testng.reporters.jq;
 
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Set;
@@ -10,15 +9,9 @@
 
 public class ResultsByClass {
   public static final Comparator<ITestResult> METHOD_NAME_COMPARATOR =
-      new Comparator<ITestResult>() {
+      Comparator.comparing(arg0 -> arg0.getMethod().getMethodName());
 
-        @Override
-        public int compare(ITestResult arg0, ITestResult arg1) {
-          return arg0.getMethod().getMethodName().compareTo(arg1.getMethod().getMethodName());
-        }
-      };
-
-  private ListMultiMap<Class<?>, ITestResult> m_results = Maps.newListMultiMap();
+  private final ListMultiMap<Class<?>, ITestResult> m_results = Maps.newListMultiMap();
 
   public void addResult(Class<?> c, ITestResult tr) {
     m_results.put(c, tr);
@@ -26,7 +19,7 @@ public void addResult(Class<?> c, ITestResult tr) {
 
   public List<ITestResult> getResults(Class<?> c) {
     List<ITestResult> result = m_results.get(c);
-    Collections.sort(result, METHOD_NAME_COMPARATOR);
+    result.sort(METHOD_NAME_COMPARATOR);
     return result;
   }
 
diff --git a/testng-core/src/test/java/test/commandline/CommandLineOverridesXml.java b/testng-core/src/test/java/test/commandline/CommandLineOverridesXml.java
index c81cd57b97..b647dd01e3 100644
--- a/testng-core/src/test/java/test/commandline/CommandLineOverridesXml.java
+++ b/testng-core/src/test/java/test/commandline/CommandLineOverridesXml.java
@@ -4,6 +4,7 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Arrays;
@@ -89,8 +90,8 @@ public void ensureNoNullPointerExceptionIsThrown() throws IOException {
 
   private static String createTemporarySuiteAndGetItsPath() throws IOException {
     Path file = Files.createTempFile("testng", ".xml");
-    org.testng.reporters.Files.writeFile(
-        buildSuiteContentThatRefersToInvalidTestClass(), file.toFile());
+    Files.write(
+        file, buildSuiteContentThatRefersToInvalidTestClass().getBytes(StandardCharsets.UTF_8));
     return file.toFile().getAbsolutePath();
   }
 
diff --git a/testng-core/src/test/java/test/dataprovider/InterceptorTest.java b/testng-core/src/test/java/test/dataprovider/InterceptorTest.java
index 7cbb0ad929..8217066281 100644
--- a/testng-core/src/test/java/test/dataprovider/InterceptorTest.java
+++ b/testng-core/src/test/java/test/dataprovider/InterceptorTest.java
@@ -4,12 +4,13 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.util.Collections;
 import org.testng.IDataProviderInterceptor;
 import org.testng.TestNG;
 import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;
-import org.testng.reporters.Files;
 import test.SimpleBaseTest;
 import test.TestHelper;
 import test.dataprovider.issue2111.CountingListener;
@@ -61,7 +62,7 @@ public void ensureInterceptorIsInvokedViaListenersTag(Class<?> testClass) throws
             + "</suite>";
     xml = String.format(xml, testClass.getName());
     File suiteFile = File.createTempFile("testng", ".xml");
-    Files.writeFile(xml, suiteFile);
+    Files.write(suiteFile.toPath(), xml.getBytes(StandardCharsets.UTF_8));
     TestNG testng = create();
     testng.setTestSuites(Collections.singletonList(suiteFile.getAbsolutePath()));
     CountingListener counter = new CountingListener();
diff --git a/testng-core/src/test/java/test/groups/issue1834/IssueTest.java b/testng-core/src/test/java/test/groups/issue1834/IssueTest.java
index 09cb839075..d510cac6d5 100644
--- a/testng-core/src/test/java/test/groups/issue1834/IssueTest.java
+++ b/testng-core/src/test/java/test/groups/issue1834/IssueTest.java
@@ -4,10 +4,11 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.util.Collections;
 import org.testng.TestNG;
 import org.testng.annotations.Test;
-import org.testng.reporters.Files;
 import test.SimpleBaseTest;
 import test.TestHelper;
 
@@ -16,7 +17,7 @@ public class IssueTest extends SimpleBaseTest {
   @Test(description = "GITHUB-1834")
   public void ensureDependenciesDefinedInSuiteAreHonored() throws IOException {
     File file = File.createTempFile("1834", ".xml");
-    Files.writeFile(asSuite(), file);
+    Files.write(file.toPath(), asSuite().getBytes(StandardCharsets.UTF_8));
     TestNG testng = create();
     testng.setTestSuites(Collections.singletonList(file.getAbsolutePath()));
     OutputGatheringListener listener = new OutputGatheringListener();
diff --git a/testng-core/src/test/java/test/override/OverrideTest.java b/testng-core/src/test/java/test/override/OverrideTest.java
index 3d00f31d64..8b6b3670e6 100644
--- a/testng-core/src/test/java/test/override/OverrideTest.java
+++ b/testng-core/src/test/java/test/override/OverrideTest.java
@@ -2,13 +2,14 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.util.Collections;
 import org.testng.Assert;
 import org.testng.TestListenerAdapter;
 import org.testng.TestNG;
 import org.testng.TestNGException;
 import org.testng.annotations.Test;
-import org.testng.reporters.Files;
 import test.SimpleBaseTest;
 import test.TestHelper;
 
@@ -26,7 +27,7 @@ private static File createTempFile(String content) {
 
       // Delete temp file when program exits.
       result.deleteOnExit();
-      Files.writeFile(content, result);
+      Files.write(result.toPath(), content.getBytes(StandardCharsets.UTF_8));
 
       return result;
     } catch (IOException e) {
diff --git a/testng-core/src/test/java/test/yaml/YamlTest.java b/testng-core/src/test/java/test/yaml/YamlTest.java
index 85d639f373..3d5f6fc33f 100644
--- a/testng-core/src/test/java/test/yaml/YamlTest.java
+++ b/testng-core/src/test/java/test/yaml/YamlTest.java
@@ -6,6 +6,7 @@
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.Collection;
 import java.util.regex.Matcher;
@@ -15,7 +16,6 @@
 import org.testng.annotations.Test;
 import org.testng.internal.Yaml;
 import org.testng.internal.YamlParser;
-import org.testng.reporters.Files;
 import org.testng.xml.SuiteXmlParser;
 import org.testng.xml.XmlSuite;
 import org.testng.xml.internal.Parser;
@@ -55,7 +55,7 @@ public void testParameterInclusion() throws IOException {
     assertThat(count).isEqualTo(5);
     File newSuite = File.createTempFile("suite", ".xml");
     newSuite.deleteOnExit();
-    Files.writeFile(yaml.toString(), newSuite);
+    Files.write(newSuite.toPath(), yaml.toString().getBytes(StandardCharsets.UTF_8));
     assertThat(parser.parse(newSuite.getAbsolutePath(), new FileInputStream(file), false))
         .isEqualTo(xmlSuite);
   }