We encountered a resultset.getInt() being passed into a setter method designed to receive a long. Naturally this worked, however yesterday the bigint being queried returned a number greater than Integer.MAX_VALUE. I would like to inspect code base for this pattern
// target method
public void foo(long l){}
// client code
foo(7);
Related
So I am trying to get into app development and following this guys yt-tutorial (yt-vid from The Net Ninja). However I stumbled over the following error:
Non-nullable instance field ‘{0}’ must be initialized. (error on dart.dev explained). The whole code is shown in this image
img coding: comparison mine with yt:
The issue I am facing is that I don't understand the origin of that error. I understand that you can't use a variable that was not initialized yet and that this error is trying to tell you that before you run the code and run into an exception in runtime.
I also know that I can fix this using "late" in front of the variables, but as far as I'm concerned that's just "ignoring" the error.
So my main question is: why do I have this error while the yt doesn't even though we have (except for some names and assignments) the same code?
I appreciate every answer and hope you have a great day
the links:
error on dart.dev explained
You should change your User class to:
class User {
String username;
int age;
User(this.username, this.age);
}
By doing so, the variables will be initialized with values (since we are then able to use this values in the constructor body) as part of initialization of the object.
Dart does object creation in two steps:
Initialize object.
Run constructor body.
So when the constructor body is running, the object must be initialized with values (well, the non-nullable values at least). To do so, we have a code block which is executed before { } like:
class User {
String username;
int age;
User(String username, int age)
: this.username = username,
this.age = age;
}
But since this is kinda redundant, we have the shortcut form as I first suggested.
When initializing an object, we are not allowed to use variables from the object since the object is ongoing its creation.
I am implementing a Pub/Sub to BigQuery pipeline. It looks similar to How to create read transform using ParDo and DoFn in Apache Beam, but here, I have already a PCollection created.
I am following what is described in the Apache Beam documentation to implement a ParDo operation to prepare a table row using the following pipeline:
static class convertToTableRowFn extends DoFn<PubsubMessage, TableRow> {
#ProcessElement
public void processElement(ProcessContext c) {
PubsubMessage message = c.element();
// Retrieve data from message
String rawData = message.getData();
Instant timestamp = new Instant(new Date());
// Prepare TableRow
TableRow row = new TableRow().set("message", rawData).set("ts_reception", timestamp);
c.output(row);
}
}
// Read input from Pub/Sub
pipeline.apply("Read from Pub/Sub",PubsubIO.readMessagesWithAttributes().fromTopic(topicPath))
.apply("Prepare raw data for insertion", ParDo.of(new convertToTableRowFn()))
.apply("Insert in Big Query", BigQueryIO.writeTableRows().to(BQTable));
I found the DoFn function in a gist.
I keep getting the following error:
The method apply(String, PTransform<? super PCollection<PubsubMessage>,OutputT>) in the type PCollection<PubsubMessage> is not applicable for the arguments (String, ParDo.SingleOutput<PubsubMessage,TableRow>)
I always understood that a ParDo/DoFn operations is a element-wise PTransform operation, am I wrong ? I never got this type of error in Python, so I'm a bit confused about why this is happening.
You're right, ParDos are element-wise transforms and your approach looks correct.
What you're seeing is the compilation error. Something like this happens when the argument type of the apply() method that was inferred by java compiler doesn't match the type of the actual input, e.g. convertToTableRowFn.
From the error you're seeing it looks like java infers that the second parameter for apply() is of type PTransform<? super PCollection<PubsubMessage>,OutputT>, while you're passing the subclass of ParDo.SingleOutput<PubsubMessage,TableRow> instead (your convertToTableRowFn). Looking at the definition of SingleOutput your convertToTableRowFn is basically a PTransform<PCollection<? extends PubsubMessage>, PCollection<TableRow>>. And java fails to use it in apply where it expects PTransform<? super PCollection<PubsubMessage>,OutputT>.
What looks suspicious is that java didn't infer the OutputT to PCollection<TableRow>. One reason it would fail to do so if you have other errors. Are you sure you don't have other errors as well?
For example, looking at convertToTableRowFn you're calling message.getData() which doesn't exist when I'm trying to do it and it fails compilation there. In my case I need to do something like this instead: rawData = new String(message.getPayload(), Charset.defaultCharset()). Also .to(BQTable)) expects a string (e.g. a string representing the BQ table name) as an argument, and you're passing some unknown symbol BQTable (maybe it exists in your program somewhere though and this is not a problem in your case).
After I fix these two errors your code compiles for me, apply() is fully inferred and the types are compatible.
i have strange errors got from my flutter pages do some math computation with null value. or i assume it was makes errors happening.
in my case i do computation such as (120 * null) inside stateful widget init section. when i build in release mode. I have debug view which means it read background in my apps and shows:
NoSuchMethodError: The method '_mulFromInteger' was called on null.
Receiver: null
Tried Calling:_mulFromInteger(134)
is multiply operations (*) have method behind of it? or can anyone explain what is _mulFromInteger?
This implementation of int in dart is provided by the class _IntegerImplementation. In this class you can see:
num operator *(num other) => other._mulFromInteger(this);
You can see that the implementation of the operator * calls _mulFromInteger on the argument. That's why you get this error.
To lone travelers stumbling upon this: see comments for the answer.
...
Writing a Java wrapper for a native library. A device generates data samples and stores them as structs. Two native ways of accessing them: either you request one with a getSample(&sampleStruct) or you set a callback function. Now, here is what does work:
The polling method does fill the JNA Structure
The callback function is called after being set
In fact, I am currently getting the sample right from the callback function
The problem: trying to do anything with the callback argument, which should be a struct, causes an "invalid memory access". Declaring the argument as the Structure does this, so I declared it as a Pointer. Trying a Pointer.getInt(0) causes invalid memory access. So then I declared the argument as an int, and an int is delivered; in fact, it looks very much like the first field of the struct I am trying to get! So does it mean that the struct was at that address but disappeared before Java had time to access it?
This is what I am doing now:
public class SampleCallback implements Callback{
SampleStruct sample;
public int callback(Pointer refToSample) throws IOException{
lib.INSTANCE.GetSample(sample); // works no problem
adapter.handleSample(sample);
return 1;
} ...
But neither of these does:
public int callback(SampleStruct sample) throws IOException{
adapter.handleSample(sample);
return 1;
}
...
public int callback(Pointer refToSample) throws IOException{
SampleStruct sample = new SampleStruct();
sample.timestamp = refToSample.getInt(0);
...
adapter.handleSample(sample);
return 1;
}
Also, this does in fact deliver the timestamp,
public int callback(int timestamp) throws IOException{
System.out.println("It is " + timestamp + "o'clock");
return 1;
}
but I would really prefer the whole struct.
This is clearly not going to be a popular topic and I do have a working solution, so the description is not exactly full. Will copy anything else that might be helpful if requested. Gratitude prematurely extended.
Good day,
I have problem. I want to simulate some errors in hacklang.
<?hh
namespace Exsys\HHVM;
class HHVMFacade{
private $vector = Vector {1,2,3};
public function echoProduct() : Vector<string>{
return $this->vector;
}
public function test(Vector<string> $vector) : void{
var_dump($vector);
}
}
Function echoProduct() returns Vector of strings. But private property $vector is Vector of integers. When I call echoFunction and returning value use as argument for function test(). I get
object(HH\Vector)#35357 (3) { [0]=> int(1) [1]=> int(2) [2]=> int(3) }
Why? I am expecting some error because types mismatch.
There's two things at play here:
Generics aren't reified, so the runtime has no information about them. This means the runtime is only checking that you're returning a Vector.
$this->vector itself isn't typed. This means the type checker (hh_client) treats it as a unknown type. Unknown types match against everything, so there's no problem returning an unknown type where a Vector<string> is expected.
This is to allow you to gradually type your code. Whenever a type isn't known, the type checker just assumes that the developer knows what's happening.
The first thing I'd do is change the file from partial mode to strict mode, which simply involves changing from <?hh to <?hh // strict. This causes the type checker to complain about any missing type information (as well as a couple of other things, like no superglobals and you can't call non-Hack code).
This produces the error:
test.hh:6:13,19: Please add a type hint (Naming[2001])
If you then type $vector as Vector<int> (private Vector<int> $vector), hh_client then produces:
test.hh:9:16,28: Invalid return type (Typing[4110])
test.hh:8:44,49: This is a string
test.hh:6:20,22: It is incompatible with an int
test.hh:8:44,49: Considering that this type argument is invariant with respect to Vector
Which is the error you expected. You can also get this error simply by adding the type to $vector, without switching to strict mode, though I prefer to write my Hack in the strongest mode that the code supports.
With more recent versions of HHVM, the type checker is called whenever Hack code is run (there's an INI flag to turn this off), so causing the type mismatch will also cause execution of the code to fail.