关于Java的Byte和Integer的equals及==对比方式的问题

Question

Byte a = 1;
Byte b = new Byte("1");
Byte c = 0x1;
System.out.println(a.equals(1));
System.out.println(a==1);
System.out.println(a.equals(b));
System.out.println(a==b);
System.out.println(c.equals(1));
System.out.println(c==1);
System.out.println("======================");
Integer i = 1;
System.out.println(i.equals(1));
System.out.println(i==1);

如上面的代码，为什么Byte的equals不能直接跟1比？比较结果为false；而Integer却可以？

Answer 1

/**
* Compares this object to the specified object. The result is
* {@code true} if and only if the argument is not
* {@code null} and is an {@code Integer} object that
* contains the same {@code int} value as this object.
*
* @param obj the object to compare with.
* @return {@code true} if the objects are the same;
* {@code false} otherwise.
*/
public boolean equals(Object obj) {
if (obj instanceof Integer) {
return value == ((Integer)obj).intValue();
}
return false;
}

       * Returns an {@code Integer} instance representing the specified
 * {@code int} value.  If a new {@code Integer} instance is not
 * required, this method should generally be used in preference to
 * the constructor {@link #Integer(int)}, as this method is likely
 * to yield significantly better space and time performance by
 * caching frequently requested values.
 *
 * This method will always cache values in the range -128 to 127,
 * inclusive, and may cache other values outside of this range.
 *
 * @param  i an {@code int} value.
 * @return an {@code Integer} instance representing {@code i}.
 * @since  1.5
 */
public static Integer valueOf(int i) {
    if (i >= IntegerCache.low && i <= IntegerCache.high)
        return IntegerCache.cache[i + (-IntegerCache.low)];
    return new Integer(i);
}

       /**
 * Compares this object to the specified object.  The result is
 * {@code true} if and only if the argument is not
 * {@code null} and is a {@code Byte} object that
 * contains the same {@code byte} value as this object.
 *
 * @param obj       the object to compare with
 * @return          {@code true} if the objects are the same;
 *                  {@code false} otherwise.
 */
public boolean equals(Object obj) {
    if (obj instanceof Byte) {
        return value == ((Byte)obj).byteValue();
    }
    return false;
}

    Integer的equals方法是转为int类型 ，Byte的equals是byte类型  ，1是int类型