How to call Kotlin function with function as parameter in Java Code?

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I have a kotlin method as follows:

fun methodWithCallBackAsParameter(callback:() -> Unit) {

    //Do Somejob

    callback()

}

In kotlin we simply use this method with following syntax:

methodWithCallBackAsParameter {

    //Some Instructions here.

}

Now I want to use this Kotlin method in a Java class but I am not able to figure out how.

asked Nov 16 '18 at 13:13

Prajeet Shrestha

5,16432148

Doesn't methodWithCallbackAsParameter(() -> { }); work?

– EpicPandaForce
Nov 16 '18 at 13:14

It says missing return statement.

– Prajeet Shrestha
Nov 16 '18 at 13:16

I tried returning Unit.INSTANCE; it now says, Lambda expressions are not supported at language level 7.

– Prajeet Shrestha
Nov 16 '18 at 13:19

Possible duplicate of Is it possible to use Java 8 for Android development?

– DaveyDaveDave
Nov 16 '18 at 13:58

1

If you are using Android Studio 3.0+ then you just need to enable Java 8 language features by copy-pasting a block of code into your build.gradle, see developer.android.com/studio/write/java8-support

– EpicPandaForce
Nov 16 '18 at 14:02

add a comment |

I have a kotlin method as follows:

fun methodWithCallBackAsParameter(callback:() -> Unit) {

    //Do Somejob

    callback()

}

In kotlin we simply use this method with following syntax:

methodWithCallBackAsParameter {

    //Some Instructions here.

}

Now I want to use this Kotlin method in a Java class but I am not able to figure out how.

asked Nov 16 '18 at 13:13

Prajeet Shrestha

5,16432148

Doesn't methodWithCallbackAsParameter(() -> { }); work?

– EpicPandaForce
Nov 16 '18 at 13:14

It says missing return statement.

– Prajeet Shrestha
Nov 16 '18 at 13:16

I tried returning Unit.INSTANCE; it now says, Lambda expressions are not supported at language level 7.

– Prajeet Shrestha
Nov 16 '18 at 13:19

Possible duplicate of Is it possible to use Java 8 for Android development?

– DaveyDaveDave
Nov 16 '18 at 13:58

1

If you are using Android Studio 3.0+ then you just need to enable Java 8 language features by copy-pasting a block of code into your build.gradle, see developer.android.com/studio/write/java8-support

– EpicPandaForce
Nov 16 '18 at 14:02

add a comment |

I have a kotlin method as follows:

fun methodWithCallBackAsParameter(callback:() -> Unit) {

    //Do Somejob

    callback()

}

In kotlin we simply use this method with following syntax:

methodWithCallBackAsParameter {

    //Some Instructions here.

}

Now I want to use this Kotlin method in a Java class but I am not able to figure out how.

asked Nov 16 '18 at 13:13

Prajeet Shrestha

5,16432148

I have a kotlin method as follows:

fun methodWithCallBackAsParameter(callback:() -> Unit) {

    //Do Somejob

    callback()

}

In kotlin we simply use this method with following syntax:

methodWithCallBackAsParameter {

    //Some Instructions here.

}

Now I want to use this Kotlin method in a Java class but I am not able to figure out how.

java android lambda kotlin

asked Nov 16 '18 at 13:13

Prajeet Shrestha

5,16432148

asked Nov 16 '18 at 13:13

Prajeet Shrestha

5,16432148

asked Nov 16 '18 at 13:13

Prajeet Shrestha

5,16432148

asked Nov 16 '18 at 13:13

Prajeet Shrestha

5,16432148

asked Nov 16 '18 at 13:13

Prajeet Shrestha

5,16432148

Doesn't methodWithCallbackAsParameter(() -> { }); work?

– EpicPandaForce
Nov 16 '18 at 13:14

It says missing return statement.

– Prajeet Shrestha
Nov 16 '18 at 13:16

I tried returning Unit.INSTANCE; it now says, Lambda expressions are not supported at language level 7.

– Prajeet Shrestha
Nov 16 '18 at 13:19

Possible duplicate of Is it possible to use Java 8 for Android development?

– DaveyDaveDave
Nov 16 '18 at 13:58

1

If you are using Android Studio 3.0+ then you just need to enable Java 8 language features by copy-pasting a block of code into your build.gradle, see developer.android.com/studio/write/java8-support

– EpicPandaForce
Nov 16 '18 at 14:02

add a comment |

Doesn't methodWithCallbackAsParameter(() -> { }); work?

– EpicPandaForce
Nov 16 '18 at 13:14

It says missing return statement.

– Prajeet Shrestha
Nov 16 '18 at 13:16

I tried returning Unit.INSTANCE; it now says, Lambda expressions are not supported at language level 7.

– Prajeet Shrestha
Nov 16 '18 at 13:19

Possible duplicate of Is it possible to use Java 8 for Android development?

– DaveyDaveDave
Nov 16 '18 at 13:58

1

If you are using Android Studio 3.0+ then you just need to enable Java 8 language features by copy-pasting a block of code into your build.gradle, see developer.android.com/studio/write/java8-support

– EpicPandaForce
Nov 16 '18 at 14:02

Doesn't methodWithCallbackAsParameter(() -> { }); work?

– EpicPandaForce
Nov 16 '18 at 13:14

It says missing return statement.

– Prajeet Shrestha
Nov 16 '18 at 13:16

I tried returning Unit.INSTANCE; it now says, Lambda expressions are not supported at language level 7.

– Prajeet Shrestha
Nov 16 '18 at 13:19

Possible duplicate of Is it possible to use Java 8 for Android development?

– DaveyDaveDave
Nov 16 '18 at 13:58

If you are using Android Studio 3.0+ then you just need to enable Java 8 language features by copy-pasting a block of code into your build.gradle, see developer.android.com/studio/write/java8-support

– EpicPandaForce
Nov 16 '18 at 14:02

add a comment |

2 Answers
2

active

oldest

votes

Just return Unit.INSTANCE in the end of the lambda expression.

answered Nov 16 '18 at 13:19

Andrey Ilyunin

1,287224

I tried returning Unit.INSTANCE; it now says, Lambda expressions are not supported at language level 7.

– Prajeet Shrestha
Nov 16 '18 at 13:19

Either set language level to 1.8 or transform the lambda into anonymous class. This error occurred because lambdas are supported from Java 1.8, and your project uses Java 1.7.

– Andrey Ilyunin
Nov 16 '18 at 13:21

add a comment |

if you want to use lambda in android you have to change your app to use Java 1.8 instead of 1.7 use can do that by it from gradle

android {

  ...

  // Configure only for each module that uses Java 8

  // language features (either in its source code or

  // through dependencies).

  compileOptions {

    sourceCompatibility JavaVersion.VERSION_1_8

    targetCompatibility JavaVersion.VERSION_1_8

  }

}

for more look this documentation https://developer.android.com/studio/write/java8-support

edited Nov 16 '18 at 14:19

answered Nov 16 '18 at 13:21

gmetax

2,55422036

While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - From Review

– Mustapha Larhrouch
Nov 16 '18 at 14:02

@MustaphaLarhrouch done

– gmetax
Nov 16 '18 at 14:19

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

Just return Unit.INSTANCE in the end of the lambda expression.

answered Nov 16 '18 at 13:19

Andrey Ilyunin

1,287224

I tried returning Unit.INSTANCE; it now says, Lambda expressions are not supported at language level 7.

– Prajeet Shrestha
Nov 16 '18 at 13:19

Either set language level to 1.8 or transform the lambda into anonymous class. This error occurred because lambdas are supported from Java 1.8, and your project uses Java 1.7.

– Andrey Ilyunin
Nov 16 '18 at 13:21

add a comment |

Just return Unit.INSTANCE in the end of the lambda expression.

answered Nov 16 '18 at 13:19

Andrey Ilyunin

1,287224

I tried returning Unit.INSTANCE; it now says, Lambda expressions are not supported at language level 7.

– Prajeet Shrestha
Nov 16 '18 at 13:19

Either set language level to 1.8 or transform the lambda into anonymous class. This error occurred because lambdas are supported from Java 1.8, and your project uses Java 1.7.

– Andrey Ilyunin
Nov 16 '18 at 13:21

add a comment |

Just return Unit.INSTANCE in the end of the lambda expression.

answered Nov 16 '18 at 13:19

Andrey Ilyunin

1,287224

Just return Unit.INSTANCE in the end of the lambda expression.

answered Nov 16 '18 at 13:19

Andrey Ilyunin

1,287224

answered Nov 16 '18 at 13:19

Andrey Ilyunin

1,287224

answered Nov 16 '18 at 13:19

Andrey Ilyunin

1,287224

answered Nov 16 '18 at 13:19

Andrey Ilyunin

1,287224

I tried returning Unit.INSTANCE; it now says, Lambda expressions are not supported at language level 7.

– Prajeet Shrestha
Nov 16 '18 at 13:19

Either set language level to 1.8 or transform the lambda into anonymous class. This error occurred because lambdas are supported from Java 1.8, and your project uses Java 1.7.

– Andrey Ilyunin
Nov 16 '18 at 13:21

add a comment |

I tried returning Unit.INSTANCE; it now says, Lambda expressions are not supported at language level 7.

– Prajeet Shrestha
Nov 16 '18 at 13:19

Either set language level to 1.8 or transform the lambda into anonymous class. This error occurred because lambdas are supported from Java 1.8, and your project uses Java 1.7.

– Andrey Ilyunin
Nov 16 '18 at 13:21

I tried returning Unit.INSTANCE; it now says, Lambda expressions are not supported at language level 7.

– Prajeet Shrestha
Nov 16 '18 at 13:19

Either set language level to 1.8 or transform the lambda into anonymous class. This error occurred because lambdas are supported from Java 1.8, and your project uses Java 1.7.

– Andrey Ilyunin
Nov 16 '18 at 13:21

add a comment |

if you want to use lambda in android you have to change your app to use Java 1.8 instead of 1.7 use can do that by it from gradle

android {

  ...

  // Configure only for each module that uses Java 8

  // language features (either in its source code or

  // through dependencies).

  compileOptions {

    sourceCompatibility JavaVersion.VERSION_1_8

    targetCompatibility JavaVersion.VERSION_1_8

  }

}

for more look this documentation https://developer.android.com/studio/write/java8-support

edited Nov 16 '18 at 14:19

answered Nov 16 '18 at 13:21

gmetax

2,55422036

While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - From Review

– Mustapha Larhrouch
Nov 16 '18 at 14:02

@MustaphaLarhrouch done

– gmetax
Nov 16 '18 at 14:19

add a comment |

if you want to use lambda in android you have to change your app to use Java 1.8 instead of 1.7 use can do that by it from gradle

android {

  ...

  // Configure only for each module that uses Java 8

  // language features (either in its source code or

  // through dependencies).

  compileOptions {

    sourceCompatibility JavaVersion.VERSION_1_8

    targetCompatibility JavaVersion.VERSION_1_8

  }

}

for more look this documentation https://developer.android.com/studio/write/java8-support

edited Nov 16 '18 at 14:19

answered Nov 16 '18 at 13:21

gmetax

2,55422036

While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - From Review

– Mustapha Larhrouch
Nov 16 '18 at 14:02

@MustaphaLarhrouch done

– gmetax
Nov 16 '18 at 14:19

add a comment |

if you want to use lambda in android you have to change your app to use Java 1.8 instead of 1.7 use can do that by it from gradle

android {

  ...

  // Configure only for each module that uses Java 8

  // language features (either in its source code or

  // through dependencies).

  compileOptions {

    sourceCompatibility JavaVersion.VERSION_1_8

    targetCompatibility JavaVersion.VERSION_1_8

  }

}

for more look this documentation https://developer.android.com/studio/write/java8-support

edited Nov 16 '18 at 14:19

answered Nov 16 '18 at 13:21

gmetax

2,55422036

if you want to use lambda in android you have to change your app to use Java 1.8 instead of 1.7 use can do that by it from gradle

android {

  ...

  // Configure only for each module that uses Java 8

  // language features (either in its source code or

  // through dependencies).

  compileOptions {

    sourceCompatibility JavaVersion.VERSION_1_8

    targetCompatibility JavaVersion.VERSION_1_8

  }

}

for more look this documentation https://developer.android.com/studio/write/java8-support

edited Nov 16 '18 at 14:19

answered Nov 16 '18 at 13:21

gmetax

2,55422036

edited Nov 16 '18 at 14:19

answered Nov 16 '18 at 13:21

gmetax

2,55422036

answered Nov 16 '18 at 13:21

gmetax

2,55422036

answered Nov 16 '18 at 13:21

gmetax

2,55422036

While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - From Review

– Mustapha Larhrouch
Nov 16 '18 at 14:02

@MustaphaLarhrouch done

– gmetax
Nov 16 '18 at 14:19

add a comment |

While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - From Review

– Mustapha Larhrouch
Nov 16 '18 at 14:02

@MustaphaLarhrouch done

– gmetax
Nov 16 '18 at 14:19

While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - From Review

– Mustapha Larhrouch
Nov 16 '18 at 14:02

@MustaphaLarhrouch done

– gmetax
Nov 16 '18 at 14:19

add a comment |

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