diff --git a/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/test/java/org/apache/hadoop/fs/http/server/TestHttpFSServerWebServer.java b/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/test/java/org/apache/hadoop/fs/http/server/TestHttpFSServerWebServer.java
index a05876620e..5250543b71 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/test/java/org/apache/hadoop/fs/http/server/TestHttpFSServerWebServer.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/test/java/org/apache/hadoop/fs/http/server/TestHttpFSServerWebServer.java
@@ -22,7 +22,7 @@
 import java.io.InputStreamReader;
 import java.net.HttpURLConnection;
 import java.net.URL;
-import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.text.MessageFormat;
 
 import org.apache.commons.io.FileUtils;
@@ -61,7 +61,7 @@ public static void beforeClass() throws Exception {
     System.setProperty("httpfs.log.dir", logsDir.getAbsolutePath());
     System.setProperty("httpfs.config.dir", confDir.getAbsolutePath());
     FileUtils.writeStringToFile(new File(confDir, "httpfs-signature.secret"),
-        "foo", Charset.forName("UTF-8"));
+        "foo", StandardCharsets.UTF_8);
   }
 
   @Before
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/datamodel/DiskBalancerCluster.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/datamodel/DiskBalancerCluster.java
index 2f54141cda..8de19aa28a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/datamodel/DiskBalancerCluster.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/datamodel/DiskBalancerCluster.java
@@ -34,6 +34,7 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Locale;
@@ -284,7 +285,7 @@ public void setOutput(String output) {
   public void createSnapshot(String snapShotName) throws IOException {
     String json = this.toJson();
     File outFile = new File(getOutput() + "/" + snapShotName);
-    FileUtils.writeStringToFile(outFile, json);
+    FileUtils.writeStringToFile(outFile, json, StandardCharsets.UTF_8);
   }
 
   /**
diff --git a/hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azure/TestShellDecryptionKeyProvider.java b/hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azure/TestShellDecryptionKeyProvider.java
index 0334c39a5c..f863e66e45 100644
--- a/hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azure/TestShellDecryptionKeyProvider.java
+++ b/hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azure/TestShellDecryptionKeyProvider.java
@@ -21,6 +21,7 @@
 import static org.apache.hadoop.test.PlatformAssumptions.assumeWindows;
 
 import java.io.File;
+import java.nio.charset.StandardCharsets;
 
 import org.apache.commons.io.FileUtils;
 import org.apache.hadoop.conf.Configuration;
@@ -65,7 +66,8 @@ public void testValidScript() throws Exception {
     // Create a simple script which echoes the given key plus the given
     // expected result (so that we validate both script input and output)
     File scriptFile = new File(TEST_ROOT_DIR, "testScript.cmd");
-    FileUtils.writeStringToFile(scriptFile, "@echo %1 " + expectedResult);
+    FileUtils.writeStringToFile(scriptFile, "@echo %1 " + expectedResult,
+            StandardCharsets.UTF_8);
 
     ShellDecryptionKeyProvider provider = new ShellDecryptionKeyProvider();
     Configuration conf = new Configuration();
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/utils/PublishedConfigurationOutputter.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/utils/PublishedConfigurationOutputter.java
index 88ecf2c7f0..8bdc102892 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/utils/PublishedConfigurationOutputter.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/utils/PublishedConfigurationOutputter.java
@@ -32,6 +32,7 @@
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.StringWriter;
+import java.nio.charset.StandardCharsets;
 import java.util.Properties;
 
 /**
@@ -61,7 +62,7 @@ public void save(File dest) throws IOException {
   }
 */
   public void save(File dest) throws IOException {
-    FileUtils.writeStringToFile(dest, asString(), Charsets.UTF_8);
+    FileUtils.writeStringToFile(dest, asString(), StandardCharsets.UTF_8);
   }
 
   /**
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/DockerClientConfigHandler.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/DockerClientConfigHandler.java
index 98bdbddbd5..13c576b22b 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/DockerClientConfigHandler.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/DockerClientConfigHandler.java
@@ -39,6 +39,7 @@
 import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.util.Iterator;
 
 /**
@@ -178,6 +179,6 @@ public static void writeDockerCredentialsToPath(File outConfigFile,
     rootNode.put(CONFIG_AUTHS_KEY, registryUrlNode);
     String json =
         mapper.writerWithDefaultPrettyPrinter().writeValueAsString(rootNode);
-    FileUtils.writeStringToFile(outConfigFile, json, Charset.defaultCharset());
+    FileUtils.writeStringToFile(outConfigFile, json, StandardCharsets.UTF_8);
   }
 }
\ No newline at end of file
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/test/java/org/apache/hadoop/yarn/util/TestProcfsBasedProcessTree.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/test/java/org/apache/hadoop/yarn/util/TestProcfsBasedProcessTree.java
index 215e5b089d..7349d22a1e 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/test/java/org/apache/hadoop/yarn/util/TestProcfsBasedProcessTree.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/test/java/org/apache/hadoop/yarn/util/TestProcfsBasedProcessTree.java
@@ -30,6 +30,7 @@
 import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import java.util.Random;
 import java.util.Vector;
@@ -154,7 +155,8 @@ public void testProcessTree() throws Exception {
         + " $(($1-1))\n" + "else\n" + " echo $$ > " + lowestDescendant + "\n"
         + "(sleep 300&\n"
         + "echo $! > " + lostDescendant + ")\n"
-        + " while true\n do\n" + "  sleep 5\n" + " done\n" + "fi");
+        + " while true\n do\n" + "  sleep 5\n" + " done\n" + "fi",
+            StandardCharsets.UTF_8);
 
     Thread t = new RogueTaskThread();
     t.start();
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/test/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/resources/TestCGroupsResourceCalculator.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/test/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/resources/TestCGroupsResourceCalculator.java
index a2ad11fc88..0158bc2503 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/test/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/resources/TestCGroupsResourceCalculator.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/test/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/resources/TestCGroupsResourceCalculator.java
@@ -26,6 +26,7 @@
 import org.junit.Test;
 
 import java.io.File;
+import java.nio.charset.StandardCharsets;
 
 import static org.mockito.Mockito.*;
 
@@ -62,7 +63,7 @@ public void testNoMemoryCGgroupMount() throws Exception {
           new File(procfs, CGroupsResourceCalculator.CGROUP),
           "7:devices:/yarn/container_1\n" +
               "6:cpuacct,cpu:/yarn/container_1\n" +
-              "5:pids:/yarn/container_1\n");
+              "5:pids:/yarn/container_1\n", StandardCharsets.UTF_8);
       CGroupsResourceCalculator calculator =
           new CGroupsResourceCalculator(
               "1234", basePath,
@@ -84,7 +85,7 @@ public void testCGgroupNotFound() throws Exception {
           "7:devices:/yarn/container_1\n" +
               "6:cpuacct,cpu:/yarn/container_1\n" +
               "5:pids:/yarn/container_1\n" +
-              "4:memory:/yarn/container_1\n");
+              "4:memory:/yarn/container_1\n", StandardCharsets.UTF_8);
 
       CGroupsResourceCalculator calculator =
           new CGroupsResourceCalculator(
@@ -118,12 +119,12 @@ public void testCPUParsing() throws Exception {
           "7:devices:/yarn/container_1\n" +
               "6:cpuacct,cpu:/yarn/container_1\n" +
               "5:pids:/yarn/container_1\n" +
-              "4:memory:/yarn/container_1\n");
+              "4:memory:/yarn/container_1\n", StandardCharsets.UTF_8);
       FileUtils.writeStringToFile(
           new File(cgcpuacctContainerDir, CGroupsResourceCalculator.CPU_STAT),
           "Can you handle this?\n" +
               "user 5415\n" +
-              "system 3632");
+              "system 3632", StandardCharsets.UTF_8);
       CGroupsResourceCalculator calculator =
           new CGroupsResourceCalculator(
               "1234", basePath,
@@ -159,10 +160,10 @@ public void testMemoryParsing() throws Exception {
       FileUtils.writeStringToFile(
           new File(procfs, CGroupsResourceCalculator.CGROUP),
               "6:cpuacct,cpu:/yarn/container_1\n" +
-              "4:memory:/yarn/container_1\n");
+              "4:memory:/yarn/container_1\n", StandardCharsets.UTF_8);
       FileUtils.writeStringToFile(
           new File(cgMemoryContainerDir, CGroupsResourceCalculator.MEM_STAT),
-          "418496512\n");
+          "418496512\n", StandardCharsets.UTF_8);
 
       CGroupsResourceCalculator calculator =
           new CGroupsResourceCalculator(
@@ -182,7 +183,7 @@ public void testMemoryParsing() throws Exception {
       // Test the case where memsw is available
       FileUtils.writeStringToFile(
           new File(cgMemoryContainerDir, CGroupsResourceCalculator.MEMSW_STAT),
-          "418496513\n");
+          "418496513\n", StandardCharsets.UTF_8);
       calculator.updateProcessTree();
       Assert.assertEquals("Incorrect swap usage",
           418496513,
@@ -206,7 +207,7 @@ public void testCPUParsingRoot() throws Exception {
       FileUtils.writeStringToFile(
           new File(cgcpuacctRootDir, CGroupsResourceCalculator.CPU_STAT),
               "user 5415\n" +
-              "system 3632");
+              "system 3632", StandardCharsets.UTF_8);
       CGroupsResourceCalculator calculator =
           new CGroupsResourceCalculator(
               null, basePath,
@@ -241,7 +242,7 @@ public void testMemoryParsingRoot() throws Exception {
     try {
       FileUtils.writeStringToFile(
           new File(cgMemoryRootDir, CGroupsResourceCalculator.MEM_STAT),
-          "418496512\n");
+              "418496512\n", StandardCharsets.UTF_8);
 
       CGroupsResourceCalculator calculator =
           new CGroupsResourceCalculator(
@@ -262,7 +263,7 @@ public void testMemoryParsingRoot() throws Exception {
       // Test the case where memsw is available
       FileUtils.writeStringToFile(
           new File(cgMemoryRootDir, CGroupsResourceCalculator.MEMSW_STAT),
-          "418496513\n");
+          "418496513\n", StandardCharsets.UTF_8);
       calculator.updateProcessTree();
       Assert.assertEquals("Incorrect swap usage",
           418496513,