8300864: Declare some fields in java.io as final

Reviewed-by: rriggs, lancea

Author: minborg

src/java.base/share/classes/java/io/BufferedInputStream.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1994, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1994, 2023, 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
@@ -55,7 +55,7 @@
  */
 public class BufferedInputStream extends FilterInputStream {
 
-    private static int DEFAULT_BUFFER_SIZE = 8192;
+    private static final int DEFAULT_BUFFER_SIZE = 8192;
 
     /**
      * As this class is used early during bootstrap, it's motivated to use

src/java.base/share/classes/java/io/BufferedReader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2023, 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
@@ -85,8 +85,8 @@ public class BufferedReader extends Reader {
     /** The skipLF flag when the mark was set */
     private boolean markedSkipLF = false;
 
-    private static int defaultCharBufferSize = 8192;
-    private static int defaultExpectedLineLength = 80;
+    private static final int DEFAULT_CHAR_BUFFER_SIZE = 8192;
+    private static final int DEFAULT_EXPECTED_LINE_LENGTH = 80;
 
     /**
      * Creates a buffering character-input stream that uses an input buffer of
@@ -113,7 +113,7 @@ public BufferedReader(Reader in, int sz) {
      * @param  in   A Reader
      */
     public BufferedReader(Reader in) {
-        this(in, defaultCharBufferSize);
+        this(in, DEFAULT_CHAR_BUFFER_SIZE);
     }
 
     /** Checks to make sure that the stream has not been closed */
@@ -414,7 +414,7 @@ private String implReadLine(boolean ignoreLF, boolean[] term) throws IOException
             }
 
             if (s == null)
-                s = new StringBuilder(defaultExpectedLineLength);
+                s = new StringBuilder(DEFAULT_EXPECTED_LINE_LENGTH);
             s.append(cb, startChar, i - startChar);
         }
     }

src/java.base/share/classes/java/io/ExpiringCache.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2023, 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
@@ -28,21 +28,21 @@
 
 package java.io;
 
-import java.util.Iterator;
 import java.util.Map;
 import java.util.LinkedHashMap;
 import java.util.Set;
 
 class ExpiringCache {
-    private long millisUntilExpiration;
-    private Map<String,Entry> map;
+
+    private static final int QUERY_OVERFLOW = 300;
+    private static final int MAX_ENTRIES = 200;
+    private final long millisUntilExpiration;
+    private final Map<String,Entry> map;
     // Clear out old entries every few queries
     private int queryCount;
-    private int queryOverflow = 300;
-    private int MAX_ENTRIES = 200;
 
     static class Entry {
-        private long   timestamp;
+        private long timestamp;
         private String val;
 
         Entry(long timestamp, String val) {
@@ -72,7 +72,7 @@ protected boolean removeEldestEntry(Map.Entry<String,Entry> eldest) {
     }
 
     synchronized String get(String key) {
-        if (++queryCount >= queryOverflow) {
+        if (++queryCount >= QUERY_OVERFLOW) {
             cleanup();
         }
         Entry entry = entryFor(key);
@@ -83,7 +83,7 @@ synchronized String get(String key) {
     }
 
     synchronized void put(String key, String val) {
-        if (++queryCount >= queryOverflow) {
+        if (++queryCount >= QUERY_OVERFLOW) {
             cleanup();
         }
         Entry entry = entryFor(key);