Why does the getResource() method return null in JDK 11?

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Simple Java program:

public static String loadText(String file) {

    StringBuilder finalString = new StringBuilder();



    InputStream in = null;

    BufferedReader reader = null;

    InputStreamReader isr = null;



    try{

        System.out.println("Text File: " + file);



        // Version 1

        //URL url = Thread.currentThread().getClass().getResource(file); 

        //in = url.openStream();



        // Version 2

        in = Class.class.getResourceAsStream(file);



        isr = new InputStreamReader(in);

        reader = new BufferedReader(isr);

        String line;

        while((line = reader.readLine()) != null) {

            finalString.append(line).append("//n");

        }

    }

    catch(IOException e) {

        e.printStackTrace();

        System.exit(-1);

    }

    finally {

        try {

            if (isr != null) { isr.close(); }

            if (reader != null) { reader.close(); }

            if (in != null) { in.close(); }

            } catch (IOException e) { e.printStackTrace(); }

        }

    return finalString.toString();

}

The getResource and getResourceAsStream methods works fine in JDK 8 (java-8-openjdk-amd64) but they always return null in JDK 11.

Questions: Why? And how can I fix this?

Operation System: Linux Mint 19 Tara x64

IDE: Eclipse 2018-12 (4.10.0)

edited Jan 3 at 12:56

Lii

7,25144163

asked Jan 3 at 11:52

Alexey

133

What's a typical value for the 'file' argument you are using?

– DodgyCodeException
Jan 3 at 12:04

Please check this question out

– caco3
Jan 3 at 12:05

4

Class.class.getResourceAsStream(...) will attempt to locate the resource in the java.base module. Replace "Class.class" with the name of your class so that it finds it in your module (or on the class path).

– Alan Bateman
Jan 3 at 12:48

Further, it’s worth learning about the try-with-resources statement…

– Holger
Jan 10 at 15:29

add a comment |

Simple Java program:

public static String loadText(String file) {

    StringBuilder finalString = new StringBuilder();



    InputStream in = null;

    BufferedReader reader = null;

    InputStreamReader isr = null;



    try{

        System.out.println("Text File: " + file);



        // Version 1

        //URL url = Thread.currentThread().getClass().getResource(file); 

        //in = url.openStream();



        // Version 2

        in = Class.class.getResourceAsStream(file);



        isr = new InputStreamReader(in);

        reader = new BufferedReader(isr);

        String line;

        while((line = reader.readLine()) != null) {

            finalString.append(line).append("//n");

        }

    }

    catch(IOException e) {

        e.printStackTrace();

        System.exit(-1);

    }

    finally {

        try {

            if (isr != null) { isr.close(); }

            if (reader != null) { reader.close(); }

            if (in != null) { in.close(); }

            } catch (IOException e) { e.printStackTrace(); }

        }

    return finalString.toString();

}

The getResource and getResourceAsStream methods works fine in JDK 8 (java-8-openjdk-amd64) but they always return null in JDK 11.

Questions: Why? And how can I fix this?

Operation System: Linux Mint 19 Tara x64

IDE: Eclipse 2018-12 (4.10.0)

edited Jan 3 at 12:56

Lii

7,25144163

asked Jan 3 at 11:52

Alexey

133

What's a typical value for the 'file' argument you are using?

– DodgyCodeException
Jan 3 at 12:04

Please check this question out

– caco3
Jan 3 at 12:05

4

Class.class.getResourceAsStream(...) will attempt to locate the resource in the java.base module. Replace "Class.class" with the name of your class so that it finds it in your module (or on the class path).

– Alan Bateman
Jan 3 at 12:48

Further, it’s worth learning about the try-with-resources statement…

– Holger
Jan 10 at 15:29

add a comment |

Simple Java program:

public static String loadText(String file) {

    StringBuilder finalString = new StringBuilder();



    InputStream in = null;

    BufferedReader reader = null;

    InputStreamReader isr = null;



    try{

        System.out.println("Text File: " + file);



        // Version 1

        //URL url = Thread.currentThread().getClass().getResource(file); 

        //in = url.openStream();



        // Version 2

        in = Class.class.getResourceAsStream(file);



        isr = new InputStreamReader(in);

        reader = new BufferedReader(isr);

        String line;

        while((line = reader.readLine()) != null) {

            finalString.append(line).append("//n");

        }

    }

    catch(IOException e) {

        e.printStackTrace();

        System.exit(-1);

    }

    finally {

        try {

            if (isr != null) { isr.close(); }

            if (reader != null) { reader.close(); }

            if (in != null) { in.close(); }

            } catch (IOException e) { e.printStackTrace(); }

        }

    return finalString.toString();

}

The getResource and getResourceAsStream methods works fine in JDK 8 (java-8-openjdk-amd64) but they always return null in JDK 11.

Questions: Why? And how can I fix this?

Operation System: Linux Mint 19 Tara x64

IDE: Eclipse 2018-12 (4.10.0)

edited Jan 3 at 12:56

Lii

7,25144163

asked Jan 3 at 11:52

Alexey

133

Simple Java program:

public static String loadText(String file) {

    StringBuilder finalString = new StringBuilder();



    InputStream in = null;

    BufferedReader reader = null;

    InputStreamReader isr = null;



    try{

        System.out.println("Text File: " + file);



        // Version 1

        //URL url = Thread.currentThread().getClass().getResource(file); 

        //in = url.openStream();



        // Version 2

        in = Class.class.getResourceAsStream(file);



        isr = new InputStreamReader(in);

        reader = new BufferedReader(isr);

        String line;

        while((line = reader.readLine()) != null) {

            finalString.append(line).append("//n");

        }

    }

    catch(IOException e) {

        e.printStackTrace();

        System.exit(-1);

    }

    finally {

        try {

            if (isr != null) { isr.close(); }

            if (reader != null) { reader.close(); }

            if (in != null) { in.close(); }

            } catch (IOException e) { e.printStackTrace(); }

        }

    return finalString.toString();

}

The getResource and getResourceAsStream methods works fine in JDK 8 (java-8-openjdk-amd64) but they always return null in JDK 11.

Questions: Why? And how can I fix this?

Operation System: Linux Mint 19 Tara x64

IDE: Eclipse 2018-12 (4.10.0)

java java-11

edited Jan 3 at 12:56

Lii

7,25144163

asked Jan 3 at 11:52

Alexey

133

edited Jan 3 at 12:56

Lii

7,25144163

asked Jan 3 at 11:52

Alexey

133

edited Jan 3 at 12:56

Lii

7,25144163

edited Jan 3 at 12:56

Lii

7,25144163

edited Jan 3 at 12:56

Lii

7,25144163

asked Jan 3 at 11:52

Alexey

133

asked Jan 3 at 11:52

Alexey

133

asked Jan 3 at 11:52

Alexey

133

What's a typical value for the 'file' argument you are using?

– DodgyCodeException
Jan 3 at 12:04

Please check this question out

– caco3
Jan 3 at 12:05

4

Class.class.getResourceAsStream(...) will attempt to locate the resource in the java.base module. Replace "Class.class" with the name of your class so that it finds it in your module (or on the class path).

– Alan Bateman
Jan 3 at 12:48

Further, it’s worth learning about the try-with-resources statement…

– Holger
Jan 10 at 15:29

add a comment |

What's a typical value for the 'file' argument you are using?

– DodgyCodeException
Jan 3 at 12:04

Please check this question out

– caco3
Jan 3 at 12:05

4

Class.class.getResourceAsStream(...) will attempt to locate the resource in the java.base module. Replace "Class.class" with the name of your class so that it finds it in your module (or on the class path).

– Alan Bateman
Jan 3 at 12:48

Further, it’s worth learning about the try-with-resources statement…

– Holger
Jan 10 at 15:29

What's a typical value for the 'file' argument you are using?

– DodgyCodeException
Jan 3 at 12:04

Please check this question out

– caco3
Jan 3 at 12:05

Class.class.getResourceAsStream(...) will attempt to locate the resource in the java.base module. Replace "Class.class" with the name of your class so that it finds it in your module (or on the class path).

– Alan Bateman
Jan 3 at 12:48

Further, it’s worth learning about the try-with-resources statement…

– Holger
Jan 10 at 15:29

add a comment |

1 Answer
1

active

oldest

votes

I've tried your application with both openjdk 8 and 11 on MacOS and it does not work with both. I think you need to look at [1] and [2] in order to understand how getResourceAsStream works.

TLDR:

If the path is absolute (i.e. starts with a slash - /), then class.getResourceAsStream() searches in the provided path

If the path is NOT absolute (i.e. does not start with a slash) , then class.getResourceAsStream() searches in a constructed path that corresponds to the package name, where the dots are replaced with slashes

So whether it works or not depends on 2 things:

Is your path absolute or not ?

Is the file located in the same package as the class or not ?

Basically in your exaple as is provided, it can never work if the path is not absolute, because Class.class.getResourceAsStream() will always resolve the path to java/lang/<file>, so your file must be in a system package. So instead you must use <MyClass>.class.getResourceAsStream() or alternatively use an absolute path

[1] https://docs.oracle.com/javase/7/docs/api/java/lang/ClassLoader.html#getResource(java.lang.String)

[2] https://docs.oracle.com/javase/7/docs/api/java/lang/Class.html#getResource%28java.lang.String%29

Update

Since Java SE 9, invoking getResourceXXX on a class in a named module will only locate the resource in that module, it will not search the class path as it did in previous release. So when you use Class.class.getResourceAsStream() it will attempt to locate the resource in module containing java.lang.Class, which is the java.base module. Obviously your resource is not in that module, so it returns null.

You have to make java 9+ search for the file in your module, which most probably is an "unnamed module". You can do that by changing Class to any class defined in your module in order to make java use the proper class loader.

edited Jan 7 at 5:09

answered Jan 3 at 12:20

Svetlin Zarev

6,00532760

I'm sorry if I am confused you. Yes, the path is absolute. TXT file in the package folder with Java class files and included in the Build Path. File Path: /configuration/options.txt

– Alexey
Jan 3 at 12:39

Ok, then it's because of the java modules. I'll update my answer

– Svetlin Zarev
Jan 3 at 12:41

Thanks for explanation. Changing from Class.class.getResourceAsStream(file) to TextTools.class.getResourceAsStream(file) solve Error.

– Alexey
Jan 3 at 12:59

add a comment |

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1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

I've tried your application with both openjdk 8 and 11 on MacOS and it does not work with both. I think you need to look at [1] and [2] in order to understand how getResourceAsStream works.

TLDR:

If the path is absolute (i.e. starts with a slash - /), then class.getResourceAsStream() searches in the provided path

If the path is NOT absolute (i.e. does not start with a slash) , then class.getResourceAsStream() searches in a constructed path that corresponds to the package name, where the dots are replaced with slashes

So whether it works or not depends on 2 things:

Is your path absolute or not ?

Is the file located in the same package as the class or not ?

[1] https://docs.oracle.com/javase/7/docs/api/java/lang/ClassLoader.html#getResource(java.lang.String)

[2] https://docs.oracle.com/javase/7/docs/api/java/lang/Class.html#getResource%28java.lang.String%29

Update

edited Jan 7 at 5:09

answered Jan 3 at 12:20

Svetlin Zarev

6,00532760

I'm sorry if I am confused you. Yes, the path is absolute. TXT file in the package folder with Java class files and included in the Build Path. File Path: /configuration/options.txt

– Alexey
Jan 3 at 12:39

Ok, then it's because of the java modules. I'll update my answer

– Svetlin Zarev
Jan 3 at 12:41

Thanks for explanation. Changing from Class.class.getResourceAsStream(file) to TextTools.class.getResourceAsStream(file) solve Error.

– Alexey
Jan 3 at 12:59

add a comment |

I've tried your application with both openjdk 8 and 11 on MacOS and it does not work with both. I think you need to look at [1] and [2] in order to understand how getResourceAsStream works.

TLDR:

If the path is absolute (i.e. starts with a slash - /), then class.getResourceAsStream() searches in the provided path

If the path is NOT absolute (i.e. does not start with a slash) , then class.getResourceAsStream() searches in a constructed path that corresponds to the package name, where the dots are replaced with slashes

So whether it works or not depends on 2 things:

Is your path absolute or not ?

Is the file located in the same package as the class or not ?

[1] https://docs.oracle.com/javase/7/docs/api/java/lang/ClassLoader.html#getResource(java.lang.String)

[2] https://docs.oracle.com/javase/7/docs/api/java/lang/Class.html#getResource%28java.lang.String%29

Update

edited Jan 7 at 5:09

answered Jan 3 at 12:20

Svetlin Zarev

6,00532760

I'm sorry if I am confused you. Yes, the path is absolute. TXT file in the package folder with Java class files and included in the Build Path. File Path: /configuration/options.txt

– Alexey
Jan 3 at 12:39

Ok, then it's because of the java modules. I'll update my answer

– Svetlin Zarev
Jan 3 at 12:41

Thanks for explanation. Changing from Class.class.getResourceAsStream(file) to TextTools.class.getResourceAsStream(file) solve Error.

– Alexey
Jan 3 at 12:59

add a comment |

I've tried your application with both openjdk 8 and 11 on MacOS and it does not work with both. I think you need to look at [1] and [2] in order to understand how getResourceAsStream works.

TLDR:

If the path is absolute (i.e. starts with a slash - /), then class.getResourceAsStream() searches in the provided path

If the path is NOT absolute (i.e. does not start with a slash) , then class.getResourceAsStream() searches in a constructed path that corresponds to the package name, where the dots are replaced with slashes

So whether it works or not depends on 2 things:

Is your path absolute or not ?

Is the file located in the same package as the class or not ?

[1] https://docs.oracle.com/javase/7/docs/api/java/lang/ClassLoader.html#getResource(java.lang.String)

[2] https://docs.oracle.com/javase/7/docs/api/java/lang/Class.html#getResource%28java.lang.String%29

Update

edited Jan 7 at 5:09

answered Jan 3 at 12:20

Svetlin Zarev

6,00532760

I've tried your application with both openjdk 8 and 11 on MacOS and it does not work with both. I think you need to look at [1] and [2] in order to understand how getResourceAsStream works.

TLDR:

If the path is absolute (i.e. starts with a slash - /), then class.getResourceAsStream() searches in the provided path

If the path is NOT absolute (i.e. does not start with a slash) , then class.getResourceAsStream() searches in a constructed path that corresponds to the package name, where the dots are replaced with slashes

So whether it works or not depends on 2 things:

Is your path absolute or not ?

Is the file located in the same package as the class or not ?

[1] https://docs.oracle.com/javase/7/docs/api/java/lang/ClassLoader.html#getResource(java.lang.String)

[2] https://docs.oracle.com/javase/7/docs/api/java/lang/Class.html#getResource%28java.lang.String%29

Update

edited Jan 7 at 5:09

answered Jan 3 at 12:20

Svetlin Zarev

6,00532760

edited Jan 7 at 5:09

answered Jan 3 at 12:20

Svetlin Zarev

6,00532760

answered Jan 3 at 12:20

Svetlin Zarev

6,00532760

answered Jan 3 at 12:20

Svetlin Zarev

6,00532760

I'm sorry if I am confused you. Yes, the path is absolute. TXT file in the package folder with Java class files and included in the Build Path. File Path: /configuration/options.txt

– Alexey
Jan 3 at 12:39

Ok, then it's because of the java modules. I'll update my answer

– Svetlin Zarev
Jan 3 at 12:41

Thanks for explanation. Changing from Class.class.getResourceAsStream(file) to TextTools.class.getResourceAsStream(file) solve Error.

– Alexey
Jan 3 at 12:59

add a comment |

I'm sorry if I am confused you. Yes, the path is absolute. TXT file in the package folder with Java class files and included in the Build Path. File Path: /configuration/options.txt

– Alexey
Jan 3 at 12:39

Ok, then it's because of the java modules. I'll update my answer

– Svetlin Zarev
Jan 3 at 12:41

Thanks for explanation. Changing from Class.class.getResourceAsStream(file) to TextTools.class.getResourceAsStream(file) solve Error.

– Alexey
Jan 3 at 12:59

I'm sorry if I am confused you. Yes, the path is absolute. TXT file in the package folder with Java class files and included in the Build Path. File Path: /configuration/options.txt

– Alexey
Jan 3 at 12:39

Ok, then it's because of the java modules. I'll update my answer

– Svetlin Zarev
Jan 3 at 12:41

Thanks for explanation. Changing from Class.class.getResourceAsStream(file) to TextTools.class.getResourceAsStream(file) solve Error.

– Alexey
Jan 3 at 12:59

add a comment |

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