Java 判断相等

long a = (long) 1234567890;
long b = (long) 1234567890;
if (a == b) {
    System.out.println("基本数据类型相等");
}

Long a = (long) 1234567890;
Long b = (long) 1234567890;
if (a != null && a.equals(b)) {
    System.out.println("包装类相等");
}
if (a != null && a.longValue() == b.longValue()) {
    System.out.println("包装类相等");
}

String a1 = null;
String b1 = new String();if (a1 != null && a1.length() > 0 && a1.equals(b1)) {
    System.out.println("对象相等");
}