Java漫谈-Long判等

    public boolean equals(Object obj) {
        if (obj instanceof Long) {
            return value == ((Long)obj).longValue();
        }
        return false;
    }

Long a = 1L;
Long b = 3L;
a.equals(b); //这样既可
a.equals(b.longValue()); //无需这样

 public boolean contains(Object o) {
    return indexOf(o) >= 0;
 }

public int indexOf(Object o) {
    if (o == null) {
        for (int i = 0; i < size; i++)
            if (elementData[i]==null)
                return i;
    } else {
        for (int i = 0; i < size; i++)
            if (o.equals(elementData[i]))
                return i;
    }
    return -1;
}