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This compliant solution requires that the values read are 32-bit unsigned integers. It reads an unsigned integer value using the readInt() method. The readInt() method assumes signed values and returns a signed int; the return value is converted to a long with sign extension. The code uses an & operation to mask off the upper 32 bits of the long; , producing a value in the range of a 32-bit unsigned integer, as intended. The mask size should be chosen to match the size of the unsigned integer values being read.

public static long getInteger(DataInputStream is) throws IOException {
  return is.readInt() & 0xFFFFFFFFL; // maskMask with 32 one-bits
}

As a general principle, you should always be aware of the signedness of the data you are reading.

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Treating unsigned data as though it were signed produces incorrect values and can lead to lost or misinterpreted data.

Automated Detection

Automated detection is infeasible in the general case.

Bibliography

[API 2006]	Class DataInputStream: method readInt
[Harold 1997]	Chapter 2, "Primitive Data Types, Cross-Platform Issues, Unsigned Integers"
[Hitchens 2002]	Section 2.4.5, "Accessing Unsigned Data"
[Seacord 2015]	Image Modified NUM03-J. Use integer types that can fully represent the possible range of unsigned data LiveLesson

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