What's the best way to check if a Reader is empty?
I need to detect if a Reader is empty (will yield no data), before I pass the reader to some external function.
The best I can come up with is to wrap my Reader in a BufferedReader which guarantees to provide mark/reset functionality, and then attempt to read a single character before resetting the stream to its original position.
BufferedReader buffered = new BufferedReader(myReader);
if (!isEmpty(buffered)) {
someOtherFunction(buffered);
}
private boolean isEmpty(BufferedReader reader) throws IOException {
reader.mark(1);
int c = reader.read();
reader.reset();
return c < 0;
}
Is there a better way?
java bufferedreader is-empty
asked Nov 20 '18 at 21:53
Graham Borland
48.5k16117162
add a comment |
I need to detect if a Reader is empty (will yield no data), before I pass the reader to some external function.
The best I can come up with is to wrap my Reader in a BufferedReader which guarantees to provide mark/reset functionality, and then attempt to read a single character before resetting the stream to its original position.
BufferedReader buffered = new BufferedReader(myReader);
if (!isEmpty(buffered)) {
someOtherFunction(buffered);
}
private boolean isEmpty(BufferedReader reader) throws IOException {
reader.mark(1);
int c = reader.read();
reader.reset();
return c < 0;
}
Is there a better way?
java bufferedreader is-empty
asked Nov 20 '18 at 21:53
Graham Borland
48.5k16117162
add a comment |
I need to detect if a Reader is empty (will yield no data), before I pass the reader to some external function.
The best I can come up with is to wrap my Reader in a BufferedReader which guarantees to provide mark/reset functionality, and then attempt to read a single character before resetting the stream to its original position.
BufferedReader buffered = new BufferedReader(myReader);
if (!isEmpty(buffered)) {
someOtherFunction(buffered);
}
private boolean isEmpty(BufferedReader reader) throws IOException {
reader.mark(1);
int c = reader.read();
reader.reset();
return c < 0;
}
Is there a better way?
java bufferedreader is-empty
asked Nov 20 '18 at 21:53
Graham Borland
48.5k16117162
I need to detect if a Reader is empty (will yield no data), before I pass the reader to some external function.
The best I can come up with is to wrap my Reader in a BufferedReader which guarantees to provide mark/reset functionality, and then attempt to read a single character before resetting the stream to its original position.
BufferedReader buffered = new BufferedReader(myReader);
if (!isEmpty(buffered)) {
someOtherFunction(buffered);
}
private boolean isEmpty(BufferedReader reader) throws IOException {
reader.mark(1);
int c = reader.read();
reader.reset();
return c < 0;
}
Is there a better way?
java bufferedreader is-empty
java bufferedreader is-empty
asked Nov 20 '18 at 21:53
Graham Borland
48.5k16117162
asked Nov 20 '18 at 21:53
Graham Borland
48.5k16117162
asked Nov 20 '18 at 21:53
Graham Borland
48.5k16117162
asked Nov 20 '18 at 21:53
Graham Borland
48.5k16117162
asked Nov 20 '18 at 21:53
Graham Borland
48.5k16117162
48.5k16117162
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
Use ready() to check stream is available to read or not here docs
And also recommended null check before checking ready()
public boolean ready() throws IOException
Tells whether this stream is ready to be read. A buffered character stream is ready if the buffer is not empty, or if the underlying character stream is ready.
Note :
True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.
answered Nov 20 '18 at 22:04
Deadpool
4,3462326
add a comment |
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%2f53402149%2fwhats-the-best-way-to-check-if-a-reader-is-empty%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Use ready() to check stream is available to read or not here docs
And also recommended null check before checking ready()
public boolean ready() throws IOException
Tells whether this stream is ready to be read. A buffered character stream is ready if the buffer is not empty, or if the underlying character stream is ready.
Note :
True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.
answered Nov 20 '18 at 22:04
Deadpool
4,3462326
add a comment |
Use ready() to check stream is available to read or not here docs
And also recommended null check before checking ready()
public boolean ready() throws IOException
Tells whether this stream is ready to be read. A buffered character stream is ready if the buffer is not empty, or if the underlying character stream is ready.
Note :
True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.
answered Nov 20 '18 at 22:04
Deadpool
4,3462326
add a comment |
Use ready() to check stream is available to read or not here docs
And also recommended null check before checking ready()
public boolean ready() throws IOException
Tells whether this stream is ready to be read. A buffered character stream is ready if the buffer is not empty, or if the underlying character stream is ready.
Note :
True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.
answered Nov 20 '18 at 22:04
Deadpool
4,3462326
Use ready() to check stream is available to read or not here docs
And also recommended null check before checking ready()
public boolean ready() throws IOException
Tells whether this stream is ready to be read. A buffered character stream is ready if the buffer is not empty, or if the underlying character stream is ready.
Note :
True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.
answered Nov 20 '18 at 22:04
Deadpool
4,3462326
edited Nov 20 '18 at 22:16
answered Nov 20 '18 at 22:04
Deadpool
4,3462326
answered Nov 20 '18 at 22:04
Deadpool
4,3462326
answered Nov 20 '18 at 22:04
Deadpool
4,3462326
4,3462326
add a comment |
add a comment |
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.
Some of your past answers have not been well-received, and you're in danger of being blocked from answering.
Please pay close attention to the following guidance:
- 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%2f53402149%2fwhats-the-best-way-to-check-if-a-reader-is-empty%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
