8334742: Change java.time month/day field types to 'byte'

src/java.base/share/classes/java/time/LocalDate.java

@@ -182,11 +182,11 @@ public final class LocalDate
     /**
      * @serial The month-of-year.
      */
-    private final short month;
+    private final byte month;
     /**
      * @serial The day-of-month.
      */
-    private final short day;
+    private final byte day;
 
     //-----------------------------------------------------------------------
     /**
@@ -490,8 +490,8 @@ private static LocalDate resolvePreviousValid(int year, int month, int day) {
      */
     private LocalDate(int year, int month, int dayOfMonth) {
         this.year = year;
-        this.month = (short) month;
-        this.day = (short) dayOfMonth;
+        this.month = (byte) month;
+        this.day = (byte) dayOfMonth;
     }
 
     //-----------------------------------------------------------------------

src/java.base/share/classes/java/time/MonthDay.java

@@ -146,11 +146,11 @@ public final class MonthDay
     /**
      * @serial The month-of-year, not null.
      */
-    private final int month;
+    private final byte month;
     /**
      * @serial The day-of-month.
      */
-    private final int day;
+    private final byte day;
 
     //-----------------------------------------------------------------------
     /**
@@ -319,8 +319,8 @@ public static MonthDay parse(CharSequence text, DateTimeFormatter formatter) {
      * @param dayOfMonth  the day-of-month to represent, validated from 1 to 29-31
      */
     private MonthDay(int month, int dayOfMonth) {
-        this.month = month;
-        this.day = dayOfMonth;
+        this.month = (byte) month;
+        this.day = (byte) dayOfMonth;
     }
 
     //-----------------------------------------------------------------------

src/java.base/share/classes/java/time/YearMonth.java

@@ -153,7 +153,7 @@ public final class YearMonth
     /**
      * @serial The month-of-year, not null.
      */
-    private final int month;
+    private final byte month;
 
     //-----------------------------------------------------------------------
     /**
@@ -306,7 +306,7 @@ public static YearMonth parse(CharSequence text, DateTimeFormatter formatter) {
      */
     private YearMonth(int year, int month) {
         this.year = year;
-        this.month = month;
+        this.month = (byte) month;
     }
 
     /**

src/java.base/share/classes/java/time/chrono/HijrahDate.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2025, 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
@@ -137,11 +137,11 @@ public final class HijrahDate
     /**
      * The month-of-year.
      */
-    private final transient int monthOfYear;
+    private final transient byte monthOfYear;
     /**
      * The day-of-month.
      */
-    private final transient int dayOfMonth;
+    private final transient byte dayOfMonth;
 
     //-------------------------------------------------------------------------
     /**
@@ -273,8 +273,8 @@ private HijrahDate(HijrahChronology chrono, int prolepticYear, int monthOfYear,
 
         this.chrono = chrono;
         this.prolepticYear = prolepticYear;
-        this.monthOfYear = monthOfYear;
-        this.dayOfMonth = dayOfMonth;
+        this.monthOfYear = (byte) monthOfYear;
+        this.dayOfMonth = (byte) dayOfMonth;
     }
 
     /**
@@ -287,8 +287,8 @@ private HijrahDate(HijrahChronology chrono, long epochDay) {
 
         this.chrono = chrono;
         this.prolepticYear = dateInfo[0];
-        this.monthOfYear = dateInfo[1];
-        this.dayOfMonth = dateInfo[2];
+        this.monthOfYear = (byte) dateInfo[1];
+        this.dayOfMonth = (byte) dateInfo[2];
     }
 
     //-----------------------------------------------------------------------