diff --git a/services/core/java/com/android/server/NsdService.java b/services/core/java/com/android/server/NsdService.java
index d907505..84f40cb 100644
--- a/services/core/java/com/android/server/NsdService.java
+++ b/services/core/java/com/android/server/NsdService.java
@@ -824,7 +824,7 @@
 
         @Override
         public String toString() {
-            StringBuffer sb = new StringBuffer();
+            StringBuilder sb = new StringBuilder();
             sb.append("mChannel ").append(mChannel).append("\n");
             sb.append("mMessenger ").append(mMessenger).append("\n");
             sb.append("mResolvedService ").append(mResolvedService).append("\n");
diff --git a/services/core/java/com/android/server/net/NetworkStatsAccess.java b/services/core/java/com/android/server/net/NetworkStatsAccess.java
index ddc5ef2..7cdc4cc 100644
--- a/services/core/java/com/android/server/net/NetworkStatsAccess.java
+++ b/services/core/java/com/android/server/net/NetworkStatsAccess.java
@@ -111,7 +111,7 @@
         boolean hasCarrierPrivileges = tm != null &&
                 tm.checkCarrierPrivilegesForPackageAnyPhone(callingPackage) ==
                         TelephonyManager.CARRIER_PRIVILEGE_STATUS_HAS_ACCESS;
-        boolean isDeviceOwner = dpmi != null && dpmi.isActiveDeviceOwner(callingUid);
+        final boolean isDeviceOwner = dpmi != null && dpmi.isActiveDeviceOwner(callingUid);
         final int appId = UserHandle.getAppId(callingUid);
         if (hasCarrierPrivileges || isDeviceOwner
                 || appId == Process.SYSTEM_UID || appId == Process.NETWORK_STACK_UID) {
diff --git a/services/core/java/com/android/server/net/NetworkStatsCollection.java b/services/core/java/com/android/server/net/NetworkStatsCollection.java
index 6aefe41..557fa89 100644
--- a/services/core/java/com/android/server/net/NetworkStatsCollection.java
+++ b/services/core/java/com/android/server/net/NetworkStatsCollection.java
@@ -54,6 +54,8 @@
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.ArrayUtils;
+import com.android.internal.util.FastDataInput;
+import com.android.internal.util.FastDataOutput;
 import com.android.internal.util.FileRotator;
 import com.android.internal.util.IndentingPrintWriter;
 
@@ -89,6 +91,9 @@
     /** File header magic number: "ANET" */
     private static final int FILE_MAGIC = 0x414E4554;
 
+    /** Default buffer size from BufferedInputStream */
+    private static final int BUFFER_SIZE = 8192;
+
     private static final int VERSION_NETWORK_INIT = 1;
 
     private static final int VERSION_UID_INIT = 1;
@@ -434,7 +439,8 @@
 
     @Override
     public void read(InputStream in) throws IOException {
-        read((DataInput) new DataInputStream(in));
+        final FastDataInput dataIn = new FastDataInput(in, BUFFER_SIZE);
+        read(dataIn);
     }
 
     private void read(DataInput in) throws IOException {
@@ -473,8 +479,9 @@
 
     @Override
     public void write(OutputStream out) throws IOException {
-        write((DataOutput) new DataOutputStream(out));
-        out.flush();
+        final FastDataOutput dataOut = new FastDataOutput(out, BUFFER_SIZE);
+        write(dataOut);
+        dataOut.flush();
     }
 
     private void write(DataOutput out) throws IOException {