8336278: Micro-optimize Replace String.format("%n") to System.lineSeparator

Reviewed-by: dnsimon, shade

Author: wenshao

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/code/CodeUtil.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2010, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -37,7 +37,7 @@
  */
 public class CodeUtil {
 
-    public static final String NEW_LINE = String.format("%n");
+    public static final String NEW_LINE = System.lineSeparator();
 
     public static final int K = 1024;
     public static final int M = 1024 * 1024;

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotMethodData.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -318,7 +318,7 @@ public boolean isProfileMature() {
     @Override
     public String toString() {
         StringBuilder sb = new StringBuilder();
-        String nl = String.format("%n");
+        String nl = System.lineSeparator();
         String nlIndent = String.format("%n%38s", "");
         sb.append("Raw method data for ");
         sb.append(method.format("%H.%n(%p)"));

src/jdk.jfr/share/classes/jdk/jfr/internal/tool/StructuredWriter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,7 +36,7 @@ abstract class StructuredWriter {
     private int column;
     // print first event immediately so tool feels responsive
     private boolean first = true;
-    private String lineSeparator = String.format("%n");
+    private String lineSeparator = System.lineSeparator();
 
     StructuredWriter(PrintWriter p) {
         out = p;