Replace StringBuilder#append(String) with StringBuilder#append(char) (#8008)

Author: smola

dd-java-agent/agent-crashtracking/src/main/java/com/datadog/crashtracking/parsers/HotspotCrashLogParser.java

@@ -157,7 +157,7 @@ public CrashLog parse(String crashLog) {
                 pid = line.substring(pidIdx + 4, endIdx);
               }
             } else {
-              message.append(line.substring(2)).append("\n");
+              message.append(line.substring(2)).append('\n');
             }
           }
           break;

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/agent/StringTemplateBuilder.java

@@ -56,7 +56,7 @@ public String evaluate(CapturedContext context, LogProbe.LogStatus status) {
             status.addError(new EvaluationError(ex.getExpr(), ex.getMessage()));
             String msg =
                 ex instanceof RedactedException ? Redaction.REDACTED_VALUE : ex.getMessage();
-            sb.append("{").append(msg).append("}");
+            sb.append('{').append(msg).append('}');
           }
           if (!status.getErrors().isEmpty()) {
             status.setLogTemplateErrors(true);

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/probe/ProbeDefinition.java

@@ -85,7 +85,7 @@ public String concatTags() {
     StringBuilder sb = new StringBuilder();
     for (Tag tag : tags) {
       if (sb.length() > 0) {
-        sb.append(",");
+        sb.append(',');
       }
       sb.append(tag);
     }

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/sink/IntakeBatchHelper.java

@@ -61,7 +61,7 @@ private static int buildPayloadBatch(
       List<String> payloads, int start, int count, StringBuilder sb) {
     int totalSize = 0;
     int elementCount = 0;
-    sb.append("[");
+    sb.append('[');
     for (int i = start; i < start + count; i++) {
       String jsonStr = payloads.get(i);
       totalSize += jsonStr.length();
@@ -71,13 +71,13 @@ private static int buildPayloadBatch(
         break;
       }
       sb.append(jsonStr);
-      sb.append(",");
+      sb.append(',');
       elementCount++;
     }
     if (elementCount > 0) {
       sb.delete(sb.lastIndexOf(","), sb.length());
     }
-    sb.append("]");
+    sb.append(']');
     return elementCount;
   }
 

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/util/StringTokenWriter.java

@@ -31,7 +31,7 @@ public StringTokenWriter(StringBuilder sb, List<EvaluationError> evalErrors) {
   @Override
   public void prologue(Object value, String type) {
     if (inMapEntry && !initial) {
-      sb.append("=");
+      sb.append('=');
     } else if (inCollection && !initial) {
       sb.append(", ");
     }
@@ -85,7 +85,7 @@ public void primitiveArrayElement(String value, String type) {
 
   @Override
   public void collectionPrologue(Object value) {
-    sb.append("[");
+    sb.append('[');
     initial = true;
     inCollection = true;
   }
@@ -98,7 +98,7 @@ public void collectionEpilogue(Object value, boolean isComplete, int size) {
 
   @Override
   public void mapPrologue(Object value) {
-    sb.append("{");
+    sb.append('{');
     initial = true;
     inCollection = true;
   }
@@ -108,14 +108,14 @@ public void mapEntryPrologue(Map.Entry<?, ?> entry) {
     if (!initial) {
       sb.append(", ");
     }
-    sb.append("[");
+    sb.append('[');
     initial = true;
     inMapEntry = true;
   }
 
   @Override
   public void mapEntryEpilogue(Map.Entry<?, ?> entry) {
-    sb.append("]");
+    sb.append(']');
     inMapEntry = false;
   }
 
@@ -127,7 +127,7 @@ public void mapEpilogue(boolean isComplete, int size) {
 
   @Override
   public void objectPrologue(Object value) {
-    sb.append("{");
+    sb.append('{');
     initial = true;
   }
 
@@ -137,12 +137,12 @@ public void objectFieldPrologue(String fieldName, Object value, int maxDepth) {
       sb.append(", ");
     }
     initial = false;
-    sb.append(fieldName).append("=");
+    sb.append(fieldName).append('=');
   }
 
   @Override
   public void objectEpilogue(Object value) {
-    sb.append("}");
+    sb.append('}');
   }
 
   @Override
@@ -167,16 +167,16 @@ public void notCaptured(SerializerWithLimits.NotCapturedReason reason) {
         sb.append("...");
         break;
       case TIMEOUT:
-        sb.append("{").append(TIMEOUT_REASON).append("}");
+        sb.append('{').append(TIMEOUT_REASON).append('}');
         break;
       case FIELD_COUNT:
         sb.append(", ...");
         break;
       case REDACTED_IDENT:
-        sb.append("{").append(REDACTED_IDENT_REASON).append("}");
+        sb.append('{').append(REDACTED_IDENT_REASON).append('}');
         break;
       case REDACTED_TYPE:
-        sb.append("{").append(REDACTED_TYPE_REASON).append("}");
+        sb.append('{').append(REDACTED_TYPE_REASON).append('}');
         break;
       default:
         throw new RuntimeException("Unsupported NotCapturedReason: " + reason);
@@ -185,6 +185,6 @@ public void notCaptured(SerializerWithLimits.NotCapturedReason reason) {
 
   @Override
   public void notCaptured(String reason) throws Exception {
-    sb.append("(Error: ").append(reason).append(")");
+    sb.append("(Error: ").append(reason).append(')');
   }
 }

dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/sink/DebuggerSinkTest.java

@@ -322,7 +322,7 @@ public void splitDiagnosticsBatch() {
     DebuggerSink sink = createDebuggerSink(diagnosticUploader, false);
     StringBuilder largeMessageBuilder = new StringBuilder(100_001);
     for (int i = 0; i < 100_000; i++) {
-      largeMessageBuilder.append("f");
+      largeMessageBuilder.append('f');
     }
     String largeMessage = largeMessageBuilder.toString();
     for (int i = 0; i < 100; i++) {
@@ -342,7 +342,7 @@ public void splitDiagnosticsBatchDebuggerTrack() {
     DebuggerSink sink = createDebuggerSink(diagnosticUploader, true);
     StringBuilder largeMessageBuilder = new StringBuilder(100_001);
     for (int i = 0; i < 100_000; i++) {
-      largeMessageBuilder.append("f");
+      largeMessageBuilder.append('f');
     }
     String largeMessage = largeMessageBuilder.toString();
     for (int i = 0; i < 100; i++) {
@@ -362,7 +362,7 @@ public void tooLargeDiagnostic() {
     DebuggerSink sink = createDefaultDebuggerSink();
     StringBuilder tooLargeMessageBuilder = new StringBuilder(MAX_PAYLOAD + 1);
     for (int i = 0; i < MAX_PAYLOAD; i++) {
-      tooLargeMessageBuilder.append("f");
+      tooLargeMessageBuilder.append('f');
     }
     String tooLargeMessage = tooLargeMessageBuilder.toString();
     sink.getProbeDiagnosticsSink().addError(new ProbeId("1", 1), tooLargeMessage);

dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/util/CapturedValueAdapterTest.java

@@ -55,7 +55,7 @@ void collection() throws IOException {
     StringBuilder sb = new StringBuilder();
     for (int i = 0; i < 10; i++) {
       if (i > 0) {
-        sb.append(",");
+        sb.append(',');
       }
       sb.append(String.format(CAPTURED_VALUE_SIMPLE_TEMPLATE, int.class.getTypeName(), i));
     }
@@ -66,7 +66,7 @@ void collection() throws IOException {
     sb = new StringBuilder();
     for (int i = 0; i < 10; i++) {
       if (i > 0) {
-        sb.append(",");
+        sb.append(',');
       }
       sb.append(
           String.format(CAPTURED_VALUE_SIMPLE_TEMPLATE, String.class.getTypeName(), "foo" + i));

dd-java-agent/agent-logging/src/main/java/datadog/trace/logging/simplelogger/SLCompatHelper.java

@@ -108,12 +108,12 @@ private void embedException(StringBuilder buf, Throwable t) {
     if (t != null) {
       buf.append(" [exception:");
       buf.append(t.toString());
-      buf.append(".");
+      buf.append('.');
       for (StackTraceElement element : t.getStackTrace()) {
         buf.append(" at ");
         buf.append(element.toString());
       }
-      buf.append("]");
+      buf.append(']');
     }
   }
 }

dd-java-agent/agent-logs-intake/src/main/java/datadog/trace/logging/intake/LogsDispatcher.java

@@ -66,21 +66,21 @@ public void dispatch(List<Map<String, Object>> messages) {
       }
 
       if (batchCount + 1 > maxBatchRecords || batchLength + bytes.length >= maxBatchBytes) {
-        flush(batch.append("]"));
+        flush(batch.append(']'));
         batch = new StringBuilder("[");
         batchCount = 0;
         batchLength = 0;
       }
 
       if (batchCount != 0) {
-        batch.append(",");
+        batch.append(',');
       }
       batch.append(json);
       batchCount += 1;
       batchLength += bytes.length;
     }
 
-    flush(batch.append("]"));
+    flush(batch.append(']'));
   }
 
   private void flush(StringBuilder batch) {

dd-java-agent/agent-profiling/profiling-ddprof/src/main/java/com/datadog/profiling/ddprof/DatadogProfiler.java

@@ -299,7 +299,7 @@ String cmdStartProfiling(Path file) throws IllegalStateException {
       // wall profiling is enabled.
       cmd.append(",wall=");
       if (getWallCollapsing(configProvider)) {
-        cmd.append("~");
+        cmd.append('~');
       }
       cmd.append(getWallInterval(configProvider)).append('m');
       if (getWallContextFilter(configProvider)) {