Java-to-Kotlin translation bug

Using the latest Kotlin 1.3.10 plugin from the latest IntelliJ IDEA 2018.3, if I translate the following Java code to Kotlin:

    BufferedReader br = Files.newBufferedReader(Paths.get("filename"));

    String line;

    while ((line = br.readLine()) != null)

        System.out.println(line);

I get this:

    val br = Files.newBufferedReader(Paths.get("filename"))

    var line: String

    while ((line = br.readLine()) != null)

        println(line)

The while ((line = br.nextLine()) != null) is idiomatic Java, but its automatic translation results in illegal syntax because assignments in Kotlin are not expressions.

Is this a known bug in the Java-to-Kotlin translator?

What's the Kotlin idiomatic syntax equivalent to the above Java code?

asked Nov 22 '18 at 11:03

DodgyCodeException

3,5561424

2

youtrack.jetbrains.com/issue/KT-25765

– Thomas
Nov 22 '18 at 11:09

I suppose that declaration at an upper level is the only way

– Andrey Ilyunin
Nov 22 '18 at 11:17

1

Partly a duplicate of stackoverflow.com/questions/36879236/…

– Klitos Kyriacou
Nov 22 '18 at 11:24

1

It is a known bug, please vote for youtrack.jetbrains.com/issue/KT-6294

– Alexey Belkov
Nov 22 '18 at 12:11

add a comment |

Using the latest Kotlin 1.3.10 plugin from the latest IntelliJ IDEA 2018.3, if I translate the following Java code to Kotlin:

    BufferedReader br = Files.newBufferedReader(Paths.get("filename"));

    String line;

    while ((line = br.readLine()) != null)

        System.out.println(line);

I get this:

    val br = Files.newBufferedReader(Paths.get("filename"))

    var line: String

    while ((line = br.readLine()) != null)

        println(line)

The while ((line = br.nextLine()) != null) is idiomatic Java, but its automatic translation results in illegal syntax because assignments in Kotlin are not expressions.

Is this a known bug in the Java-to-Kotlin translator?

What's the Kotlin idiomatic syntax equivalent to the above Java code?

asked Nov 22 '18 at 11:03

DodgyCodeException

3,5561424

2

youtrack.jetbrains.com/issue/KT-25765

– Thomas
Nov 22 '18 at 11:09

I suppose that declaration at an upper level is the only way

– Andrey Ilyunin
Nov 22 '18 at 11:17

1

Partly a duplicate of stackoverflow.com/questions/36879236/…

– Klitos Kyriacou
Nov 22 '18 at 11:24

1

It is a known bug, please vote for youtrack.jetbrains.com/issue/KT-6294

– Alexey Belkov
Nov 22 '18 at 12:11

add a comment |

Using the latest Kotlin 1.3.10 plugin from the latest IntelliJ IDEA 2018.3, if I translate the following Java code to Kotlin:

    BufferedReader br = Files.newBufferedReader(Paths.get("filename"));

    String line;

    while ((line = br.readLine()) != null)

        System.out.println(line);

I get this:

    val br = Files.newBufferedReader(Paths.get("filename"))

    var line: String

    while ((line = br.readLine()) != null)

        println(line)

The while ((line = br.nextLine()) != null) is idiomatic Java, but its automatic translation results in illegal syntax because assignments in Kotlin are not expressions.

Is this a known bug in the Java-to-Kotlin translator?

What's the Kotlin idiomatic syntax equivalent to the above Java code?

asked Nov 22 '18 at 11:03

DodgyCodeException

3,5561424

Using the latest Kotlin 1.3.10 plugin from the latest IntelliJ IDEA 2018.3, if I translate the following Java code to Kotlin:

    BufferedReader br = Files.newBufferedReader(Paths.get("filename"));

    String line;

    while ((line = br.readLine()) != null)

        System.out.println(line);

I get this:

    val br = Files.newBufferedReader(Paths.get("filename"))

    var line: String

    while ((line = br.readLine()) != null)

        println(line)

The while ((line = br.nextLine()) != null) is idiomatic Java, but its automatic translation results in illegal syntax because assignments in Kotlin are not expressions.

Is this a known bug in the Java-to-Kotlin translator?

What's the Kotlin idiomatic syntax equivalent to the above Java code?

kotlin

asked Nov 22 '18 at 11:03

DodgyCodeException

3,5561424

asked Nov 22 '18 at 11:03

DodgyCodeException

3,5561424

asked Nov 22 '18 at 11:03

DodgyCodeException

3,5561424

asked Nov 22 '18 at 11:03

DodgyCodeException

3,5561424

asked Nov 22 '18 at 11:03

DodgyCodeException

3,5561424

2

youtrack.jetbrains.com/issue/KT-25765

– Thomas
Nov 22 '18 at 11:09

I suppose that declaration at an upper level is the only way

– Andrey Ilyunin
Nov 22 '18 at 11:17

1

Partly a duplicate of stackoverflow.com/questions/36879236/…

– Klitos Kyriacou
Nov 22 '18 at 11:24

1

It is a known bug, please vote for youtrack.jetbrains.com/issue/KT-6294

– Alexey Belkov
Nov 22 '18 at 12:11

add a comment |

2

youtrack.jetbrains.com/issue/KT-25765

– Thomas
Nov 22 '18 at 11:09

I suppose that declaration at an upper level is the only way

– Andrey Ilyunin
Nov 22 '18 at 11:17

1

Partly a duplicate of stackoverflow.com/questions/36879236/…

– Klitos Kyriacou
Nov 22 '18 at 11:24

1

It is a known bug, please vote for youtrack.jetbrains.com/issue/KT-6294

– Alexey Belkov
Nov 22 '18 at 12:11

youtrack.jetbrains.com/issue/KT-25765

– Thomas
Nov 22 '18 at 11:09

I suppose that declaration at an upper level is the only way

– Andrey Ilyunin
Nov 22 '18 at 11:17

Partly a duplicate of stackoverflow.com/questions/36879236/…

– Klitos Kyriacou
Nov 22 '18 at 11:24

It is a known bug, please vote for youtrack.jetbrains.com/issue/KT-6294

– Alexey Belkov
Nov 22 '18 at 12:11

add a comment |

1 Answer
1

active

oldest

votes

I think the comments have answered both of my questions, so let me compile them into a single answer.

Yes, it's a known bug, reported at youtrack.jetbrains.com/issue/KT-6294. You can vote for it (if you have a Jetbrains account) to show the developers that you would like it fixed. Thank you Alexey Belkov for bringing this to my attention.

A common way to directly translate it would be:

val br = Files.newBufferedReader(Paths.get("filename"))

var line: String

while (br.readLine().also { line = it} != null)

    println(line)

However, a better way in this particular case is:

val br = Files.newBufferedReader(Paths.get("filename"))

br.forEachLine {

    println(it)

}

Or just

File("filename").forEachLine {

    println(it)

}

(which uses a convenience method, equivalent to Java's convenience method Files.lines(Path)).

edited Nov 22 '18 at 13:19

answered Nov 22 '18 at 13:12

DodgyCodeException

3,5561424

add a comment |

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1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

I think the comments have answered both of my questions, so let me compile them into a single answer.

Yes, it's a known bug, reported at youtrack.jetbrains.com/issue/KT-6294. You can vote for it (if you have a Jetbrains account) to show the developers that you would like it fixed. Thank you Alexey Belkov for bringing this to my attention.

A common way to directly translate it would be:

val br = Files.newBufferedReader(Paths.get("filename"))

var line: String

while (br.readLine().also { line = it} != null)

    println(line)

However, a better way in this particular case is:

val br = Files.newBufferedReader(Paths.get("filename"))

br.forEachLine {

    println(it)

}

Or just

File("filename").forEachLine {

    println(it)

}

(which uses a convenience method, equivalent to Java's convenience method Files.lines(Path)).

edited Nov 22 '18 at 13:19

answered Nov 22 '18 at 13:12

DodgyCodeException

3,5561424

add a comment |

I think the comments have answered both of my questions, so let me compile them into a single answer.

Yes, it's a known bug, reported at youtrack.jetbrains.com/issue/KT-6294. You can vote for it (if you have a Jetbrains account) to show the developers that you would like it fixed. Thank you Alexey Belkov for bringing this to my attention.

A common way to directly translate it would be:

val br = Files.newBufferedReader(Paths.get("filename"))

var line: String

while (br.readLine().also { line = it} != null)

    println(line)

However, a better way in this particular case is:

val br = Files.newBufferedReader(Paths.get("filename"))

br.forEachLine {

    println(it)

}

Or just

File("filename").forEachLine {

    println(it)

}

(which uses a convenience method, equivalent to Java's convenience method Files.lines(Path)).

edited Nov 22 '18 at 13:19

answered Nov 22 '18 at 13:12

DodgyCodeException

3,5561424

add a comment |

I think the comments have answered both of my questions, so let me compile them into a single answer.

Yes, it's a known bug, reported at youtrack.jetbrains.com/issue/KT-6294. You can vote for it (if you have a Jetbrains account) to show the developers that you would like it fixed. Thank you Alexey Belkov for bringing this to my attention.

A common way to directly translate it would be:

val br = Files.newBufferedReader(Paths.get("filename"))

var line: String

while (br.readLine().also { line = it} != null)

    println(line)

However, a better way in this particular case is:

val br = Files.newBufferedReader(Paths.get("filename"))

br.forEachLine {

    println(it)

}

Or just

File("filename").forEachLine {

    println(it)

}

(which uses a convenience method, equivalent to Java's convenience method Files.lines(Path)).

edited Nov 22 '18 at 13:19

answered Nov 22 '18 at 13:12

DodgyCodeException

3,5561424

I think the comments have answered both of my questions, so let me compile them into a single answer.

Yes, it's a known bug, reported at youtrack.jetbrains.com/issue/KT-6294. You can vote for it (if you have a Jetbrains account) to show the developers that you would like it fixed. Thank you Alexey Belkov for bringing this to my attention.

A common way to directly translate it would be:

val br = Files.newBufferedReader(Paths.get("filename"))

var line: String

while (br.readLine().also { line = it} != null)

    println(line)

However, a better way in this particular case is:

val br = Files.newBufferedReader(Paths.get("filename"))

br.forEachLine {

    println(it)

}

Or just

File("filename").forEachLine {

    println(it)

}

(which uses a convenience method, equivalent to Java's convenience method Files.lines(Path)).

edited Nov 22 '18 at 13:19

answered Nov 22 '18 at 13:12

DodgyCodeException

3,5561424

edited Nov 22 '18 at 13:19

answered Nov 22 '18 at 13:12

DodgyCodeException

3,5561424

answered Nov 22 '18 at 13:12

DodgyCodeException

3,5561424

answered Nov 22 '18 at 13:12

DodgyCodeException

3,5561424

add a comment |

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