Mixing
JNI - method lookup and covariant return types
I'm looking up (using GetMethodID) various methods of Java classes, including this one:
locating Java method [position] with signature [(I)Ljava/nio/ByteBuffer;]
The position(int) method is however defined by ByteBuffer's super-class, Buffer (and according to documentation returns Buffer not ByteBuffer). I was expecting to find base-class methods when looking up the jclass of a derived class, but I wasn't expected for what seems like JNI lookup taking return type covariance into account.
The lookup succeeds - but I haven't found this feature in the docs. I'm slightly worried it might be unsafe. Anyone know a reference for the feature?
java methods java-native-interface lookup
asked Jan 1 at 20:22
haelixhaelix
1,61832034
add a comment |
I'm looking up (using GetMethodID) various methods of Java classes, including this one:
locating Java method [position] with signature [(I)Ljava/nio/ByteBuffer;]
The position(int) method is however defined by ByteBuffer's super-class, Buffer (and according to documentation returns Buffer not ByteBuffer). I was expecting to find base-class methods when looking up the jclass of a derived class, but I wasn't expected for what seems like JNI lookup taking return type covariance into account.
The lookup succeeds - but I haven't found this feature in the docs. I'm slightly worried it might be unsafe. Anyone know a reference for the feature?
java methods java-native-interface lookup
asked Jan 1 at 20:22
haelixhaelix
1,61832034
Buffer is an abstract class.. The documentation says it returns the current buffer. So if you are callingpositionon aByteBuffer, it's going to return aByteBufferwhich inheritsBuffer..
– Brandon
Jan 1 at 20:32
add a comment |
I'm looking up (using GetMethodID) various methods of Java classes, including this one:
locating Java method [position] with signature [(I)Ljava/nio/ByteBuffer;]
The position(int) method is however defined by ByteBuffer's super-class, Buffer (and according to documentation returns Buffer not ByteBuffer). I was expecting to find base-class methods when looking up the jclass of a derived class, but I wasn't expected for what seems like JNI lookup taking return type covariance into account.
The lookup succeeds - but I haven't found this feature in the docs. I'm slightly worried it might be unsafe. Anyone know a reference for the feature?
java methods java-native-interface lookup
asked Jan 1 at 20:22
haelixhaelix
1,61832034
I'm looking up (using GetMethodID) various methods of Java classes, including this one:
locating Java method [position] with signature [(I)Ljava/nio/ByteBuffer;]
The position(int) method is however defined by ByteBuffer's super-class, Buffer (and according to documentation returns Buffer not ByteBuffer). I was expecting to find base-class methods when looking up the jclass of a derived class, but I wasn't expected for what seems like JNI lookup taking return type covariance into account.
The lookup succeeds - but I haven't found this feature in the docs. I'm slightly worried it might be unsafe. Anyone know a reference for the feature?
java methods java-native-interface lookup
java methods java-native-interface lookup
asked Jan 1 at 20:22
haelixhaelix
1,61832034
asked Jan 1 at 20:22
haelixhaelix
1,61832034
asked Jan 1 at 20:22
haelixhaelix
1,61832034
asked Jan 1 at 20:22
haelixhaelix
1,61832034
asked Jan 1 at 20:22
haelixhaelix
1,61832034
1,61832034
Buffer is an abstract class.. The documentation says it returns the current buffer. So if you are callingpositionon aByteBuffer, it's going to return aByteBufferwhich inheritsBuffer..
– Brandon
Jan 1 at 20:32
add a comment |
Buffer is an abstract class.. The documentation says it returns the current buffer. So if you are callingpositionon aByteBuffer, it's going to return aByteBufferwhich inheritsBuffer..
– Brandon
Jan 1 at 20:32
Buffer is an abstract class.. The documentation says it returns the current buffer. So if you are calling
position on a ByteBuffer, it's going to return a ByteBuffer which inherits Buffer..– Brandon
Jan 1 at 20:32
Buffer is an abstract class.. The documentation says it returns the current buffer. So if you are calling
position on a ByteBuffer, it's going to return a ByteBuffer which inherits Buffer..– Brandon
Jan 1 at 20:32
add a comment |
0
active
oldest
votes
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53998671%2fjni-method-lookup-and-covariant-return-types%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
0
active
oldest
votes
0
active
oldest
votes
active
oldest
votes
active
oldest
votes
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53998671%2fjni-method-lookup-and-covariant-return-types%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Buffer is an abstract class.. The documentation says it returns the current buffer. So if you are calling
positionon aByteBuffer, it's going to return aByteBufferwhich inheritsBuffer..– Brandon
Jan 1 at 20:32