Comparing a string[] to a list of objects with stream?

-2

I have a list of:

String properties = {"prop1","prop2","prop3"};

List<CustomObject> listOfObjects; // contains objects and each object contains a property of `properties` array



class CustomObject{

   String prop1;

   String prop2;

   String prop3;



}

I want to check every properties value to every listOfObjects objects properties and check if the value is empty. I just want to check that none of the objects have empty properties.

I know there's stream() but I'm not sure how to use it correctly.

listOfObjects.stream().anyMatch(x -> x.get(/*What do i put in here?*/) == "");

Update: here's what would basically work without stream()

    for(String prop: properties) {

        for(CustomObject pdo: listOfObjects) {

            if(pdo.get(prop) == "") {

                System.out.println("Some of the required fields are empty");

        }

    }

}

edited Nov 22 '18 at 14:21

asked Nov 22 '18 at 13:51

sander

351116

Not really. Just a check whether any of the properties is empty.

– sander
Nov 22 '18 at 13:53

1

1. Why a List<Object>, use some custom object. 2. get would depend on the type of object . 3 use equals to compare strings.

– nullpointer
Nov 22 '18 at 13:55

1

There is no simple builtin facility to treat a String like an object’s property. This is not Javascript.

– Holger
Nov 22 '18 at 13:59

1

what does .get(String prop) return if the property is not found?

– Brad
Nov 22 '18 at 14:08

1

Please share the CustomObject class definition. I think that's the most crucial part that you've abstracted from the question && 3. use equals to compare strings.

– nullpointer
Nov 22 '18 at 14:23

|
show 8 more comments

-2

I have a list of:

String properties = {"prop1","prop2","prop3"};

List<CustomObject> listOfObjects; // contains objects and each object contains a property of `properties` array



class CustomObject{

   String prop1;

   String prop2;

   String prop3;



}

I want to check every properties value to every listOfObjects objects properties and check if the value is empty. I just want to check that none of the objects have empty properties.

I know there's stream() but I'm not sure how to use it correctly.

listOfObjects.stream().anyMatch(x -> x.get(/*What do i put in here?*/) == "");

Update: here's what would basically work without stream()

    for(String prop: properties) {

        for(CustomObject pdo: listOfObjects) {

            if(pdo.get(prop) == "") {

                System.out.println("Some of the required fields are empty");

        }

    }

}

edited Nov 22 '18 at 14:21

asked Nov 22 '18 at 13:51

sander

351116

Not really. Just a check whether any of the properties is empty.

– sander
Nov 22 '18 at 13:53

1

1. Why a List<Object>, use some custom object. 2. get would depend on the type of object . 3 use equals to compare strings.

– nullpointer
Nov 22 '18 at 13:55

1

There is no simple builtin facility to treat a String like an object’s property. This is not Javascript.

– Holger
Nov 22 '18 at 13:59

1

what does .get(String prop) return if the property is not found?

– Brad
Nov 22 '18 at 14:08

1

Please share the CustomObject class definition. I think that's the most crucial part that you've abstracted from the question && 3. use equals to compare strings.

– nullpointer
Nov 22 '18 at 14:23

|
show 8 more comments

-2

I have a list of:

String properties = {"prop1","prop2","prop3"};

List<CustomObject> listOfObjects; // contains objects and each object contains a property of `properties` array



class CustomObject{

   String prop1;

   String prop2;

   String prop3;



}

I want to check every properties value to every listOfObjects objects properties and check if the value is empty. I just want to check that none of the objects have empty properties.

I know there's stream() but I'm not sure how to use it correctly.

listOfObjects.stream().anyMatch(x -> x.get(/*What do i put in here?*/) == "");

Update: here's what would basically work without stream()

    for(String prop: properties) {

        for(CustomObject pdo: listOfObjects) {

            if(pdo.get(prop) == "") {

                System.out.println("Some of the required fields are empty");

        }

    }

}

edited Nov 22 '18 at 14:21

asked Nov 22 '18 at 13:51

sander

351116

I have a list of:

String properties = {"prop1","prop2","prop3"};

List<CustomObject> listOfObjects; // contains objects and each object contains a property of `properties` array



class CustomObject{

   String prop1;

   String prop2;

   String prop3;



}

I want to check every properties value to every listOfObjects objects properties and check if the value is empty. I just want to check that none of the objects have empty properties.

I know there's stream() but I'm not sure how to use it correctly.

listOfObjects.stream().anyMatch(x -> x.get(/*What do i put in here?*/) == "");

Update: here's what would basically work without stream()

    for(String prop: properties) {

        for(CustomObject pdo: listOfObjects) {

            if(pdo.get(prop) == "") {

                System.out.println("Some of the required fields are empty");

        }

    }

}

java java-stream

edited Nov 22 '18 at 14:21

asked Nov 22 '18 at 13:51

sander

351116

edited Nov 22 '18 at 14:21

asked Nov 22 '18 at 13:51

sander

351116

edited Nov 22 '18 at 14:21

asked Nov 22 '18 at 13:51

sander

351116

asked Nov 22 '18 at 13:51

sander

351116

asked Nov 22 '18 at 13:51

sander

351116

Not really. Just a check whether any of the properties is empty.

– sander
Nov 22 '18 at 13:53

1

1. Why a List<Object>, use some custom object. 2. get would depend on the type of object . 3 use equals to compare strings.

– nullpointer
Nov 22 '18 at 13:55

1

There is no simple builtin facility to treat a String like an object’s property. This is not Javascript.

– Holger
Nov 22 '18 at 13:59

1

what does .get(String prop) return if the property is not found?

– Brad
Nov 22 '18 at 14:08

1

Please share the CustomObject class definition. I think that's the most crucial part that you've abstracted from the question && 3. use equals to compare strings.

– nullpointer
Nov 22 '18 at 14:23

|
show 8 more comments

Not really. Just a check whether any of the properties is empty.

– sander
Nov 22 '18 at 13:53

1

1. Why a List<Object>, use some custom object. 2. get would depend on the type of object . 3 use equals to compare strings.

– nullpointer
Nov 22 '18 at 13:55

1

There is no simple builtin facility to treat a String like an object’s property. This is not Javascript.

– Holger
Nov 22 '18 at 13:59

1

what does .get(String prop) return if the property is not found?

– Brad
Nov 22 '18 at 14:08

1

Please share the CustomObject class definition. I think that's the most crucial part that you've abstracted from the question && 3. use equals to compare strings.

– nullpointer
Nov 22 '18 at 14:23

Not really. Just a check whether any of the properties is empty.

– sander
Nov 22 '18 at 13:53

1. Why a List<Object>, use some custom object. 2. get would depend on the type of object . 3 use equals to compare strings.

– nullpointer
Nov 22 '18 at 13:55

There is no simple builtin facility to treat a String like an object’s property. This is not Javascript.

– Holger
Nov 22 '18 at 13:59

what does .get(String prop) return if the property is not found?

– Brad
Nov 22 '18 at 14:08

Please share the CustomObject class definition. I think that's the most crucial part that you've abstracted from the question && 3. use equals to compare strings.

– nullpointer
Nov 22 '18 at 14:23

|
show 8 more comments

2 Answers
2

active

oldest

votes

Just for the sake of using Streams and anyMatch you can use this operation to check if any of the properties are blank. This is just to answer your question specifically, my suggestion is to take some time and improve this as there is a lot of room.

listOfObject.stream()

                .anyMatch(obj -> Arrays.stream(obj)

                        .anyMatch(p -> !(obj.get(p)!= null && !obj.get(p).isEmpty())));

edited Nov 22 '18 at 16:18

answered Nov 22 '18 at 14:44

Brad

1749

1

I think this is the answer I was looking for, I will test it later and accept if it does work.

– sander
Nov 22 '18 at 14:52

Instead of .equals(""), you can use .isEmpty().

– Holger
Nov 22 '18 at 15:37

Good point, made me think about the case where the value retrieved by the get method is null. Currently with .equals() it would return false and would invalidate the outcome, and with .isEmpty it would raise a NullPointerException. I will update my answer, considering this case.

– Brad
Nov 22 '18 at 16:13

@sander, out of curiosity, did it solve your issue?

– Brad
Jan 13 at 10:05

add a comment |

You can just use a list of Predicates. Each of the following predicates tests one of the properties for equality against "".

List<Predicate<CustomObject>> propertiesCheckers = 

        Arrays.asList(pdo -> "".equals(pdo.get("prop1")),

            pdo -> "".equals(pdo.get("prop2")),

            pdo -> "".equals(pdo.get("prop3")));

And this stream checks each element against the predicate, returning true when the first empty value is found:

boolean anyEmpty = listOfObjects.stream()

        .flatMap(ob -> propertiesCheckers.stream().map(pred -> pred.test(ob)))

        .anyMatch(b -> b); //returns true if any "".equals returned true



if(anyEmpty) System.out.println("Some of the required fields are empty");

edited Nov 22 '18 at 14:34

answered Nov 22 '18 at 14:03

ernest_k

23.4k42649

1. Though honestly, I am not very sure if I understand the question right. But, does this not miss the relation between the String properties in the question to the List<CustomObejct> listOfObjects somewhere? 2. There is also a typo in your checkers left with emp.

– nullpointer
Nov 22 '18 at 14:21

1

@nullpointer Thanks, fixed typo. Edited to use the added example in the question. So I'm proposing the OP change String properties to List<Predicate<CustomObject>> based on those property names.

– ernest_k
Nov 22 '18 at 14:37

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

listOfObject.stream()

                .anyMatch(obj -> Arrays.stream(obj)

                        .anyMatch(p -> !(obj.get(p)!= null && !obj.get(p).isEmpty())));

edited Nov 22 '18 at 16:18

answered Nov 22 '18 at 14:44

Brad

1749

1

I think this is the answer I was looking for, I will test it later and accept if it does work.

– sander
Nov 22 '18 at 14:52

Instead of .equals(""), you can use .isEmpty().

– Holger
Nov 22 '18 at 15:37

Good point, made me think about the case where the value retrieved by the get method is null. Currently with .equals() it would return false and would invalidate the outcome, and with .isEmpty it would raise a NullPointerException. I will update my answer, considering this case.

– Brad
Nov 22 '18 at 16:13

@sander, out of curiosity, did it solve your issue?

– Brad
Jan 13 at 10:05

add a comment |

listOfObject.stream()

                .anyMatch(obj -> Arrays.stream(obj)

                        .anyMatch(p -> !(obj.get(p)!= null && !obj.get(p).isEmpty())));

edited Nov 22 '18 at 16:18

answered Nov 22 '18 at 14:44

Brad

1749

1

I think this is the answer I was looking for, I will test it later and accept if it does work.

– sander
Nov 22 '18 at 14:52

Instead of .equals(""), you can use .isEmpty().

– Holger
Nov 22 '18 at 15:37

Good point, made me think about the case where the value retrieved by the get method is null. Currently with .equals() it would return false and would invalidate the outcome, and with .isEmpty it would raise a NullPointerException. I will update my answer, considering this case.

– Brad
Nov 22 '18 at 16:13

@sander, out of curiosity, did it solve your issue?

– Brad
Jan 13 at 10:05

add a comment |

listOfObject.stream()

                .anyMatch(obj -> Arrays.stream(obj)

                        .anyMatch(p -> !(obj.get(p)!= null && !obj.get(p).isEmpty())));

edited Nov 22 '18 at 16:18

answered Nov 22 '18 at 14:44

Brad

1749

listOfObject.stream()

                .anyMatch(obj -> Arrays.stream(obj)

                        .anyMatch(p -> !(obj.get(p)!= null && !obj.get(p).isEmpty())));

edited Nov 22 '18 at 16:18

answered Nov 22 '18 at 14:44

Brad

1749

edited Nov 22 '18 at 16:18

answered Nov 22 '18 at 14:44

Brad

1749

answered Nov 22 '18 at 14:44

Brad

1749

answered Nov 22 '18 at 14:44

Brad

1749

1

I think this is the answer I was looking for, I will test it later and accept if it does work.

– sander
Nov 22 '18 at 14:52

Instead of .equals(""), you can use .isEmpty().

– Holger
Nov 22 '18 at 15:37

Good point, made me think about the case where the value retrieved by the get method is null. Currently with .equals() it would return false and would invalidate the outcome, and with .isEmpty it would raise a NullPointerException. I will update my answer, considering this case.

– Brad
Nov 22 '18 at 16:13

@sander, out of curiosity, did it solve your issue?

– Brad
Jan 13 at 10:05

add a comment |

1

I think this is the answer I was looking for, I will test it later and accept if it does work.

– sander
Nov 22 '18 at 14:52

Instead of .equals(""), you can use .isEmpty().

– Holger
Nov 22 '18 at 15:37

Good point, made me think about the case where the value retrieved by the get method is null. Currently with .equals() it would return false and would invalidate the outcome, and with .isEmpty it would raise a NullPointerException. I will update my answer, considering this case.

– Brad
Nov 22 '18 at 16:13

@sander, out of curiosity, did it solve your issue?

– Brad
Jan 13 at 10:05

I think this is the answer I was looking for, I will test it later and accept if it does work.

– sander
Nov 22 '18 at 14:52

Instead of .equals(""), you can use .isEmpty().

– Holger
Nov 22 '18 at 15:37

Good point, made me think about the case where the value retrieved by the get method is null. Currently with .equals() it would return false and would invalidate the outcome, and with .isEmpty it would raise a NullPointerException. I will update my answer, considering this case.

– Brad
Nov 22 '18 at 16:13

@sander, out of curiosity, did it solve your issue?

– Brad
Jan 13 at 10:05

add a comment |

You can just use a list of Predicates. Each of the following predicates tests one of the properties for equality against "".

List<Predicate<CustomObject>> propertiesCheckers = 

        Arrays.asList(pdo -> "".equals(pdo.get("prop1")),

            pdo -> "".equals(pdo.get("prop2")),

            pdo -> "".equals(pdo.get("prop3")));

And this stream checks each element against the predicate, returning true when the first empty value is found:

boolean anyEmpty = listOfObjects.stream()

        .flatMap(ob -> propertiesCheckers.stream().map(pred -> pred.test(ob)))

        .anyMatch(b -> b); //returns true if any "".equals returned true



if(anyEmpty) System.out.println("Some of the required fields are empty");

edited Nov 22 '18 at 14:34

answered Nov 22 '18 at 14:03

ernest_k

23.4k42649

1. Though honestly, I am not very sure if I understand the question right. But, does this not miss the relation between the String properties in the question to the List<CustomObejct> listOfObjects somewhere? 2. There is also a typo in your checkers left with emp.

– nullpointer
Nov 22 '18 at 14:21

1

@nullpointer Thanks, fixed typo. Edited to use the added example in the question. So I'm proposing the OP change String properties to List<Predicate<CustomObject>> based on those property names.

– ernest_k
Nov 22 '18 at 14:37

add a comment |

You can just use a list of Predicates. Each of the following predicates tests one of the properties for equality against "".

List<Predicate<CustomObject>> propertiesCheckers = 

        Arrays.asList(pdo -> "".equals(pdo.get("prop1")),

            pdo -> "".equals(pdo.get("prop2")),

            pdo -> "".equals(pdo.get("prop3")));

And this stream checks each element against the predicate, returning true when the first empty value is found:

boolean anyEmpty = listOfObjects.stream()

        .flatMap(ob -> propertiesCheckers.stream().map(pred -> pred.test(ob)))

        .anyMatch(b -> b); //returns true if any "".equals returned true



if(anyEmpty) System.out.println("Some of the required fields are empty");

edited Nov 22 '18 at 14:34

answered Nov 22 '18 at 14:03

ernest_k

23.4k42649

1. Though honestly, I am not very sure if I understand the question right. But, does this not miss the relation between the String properties in the question to the List<CustomObejct> listOfObjects somewhere? 2. There is also a typo in your checkers left with emp.

– nullpointer
Nov 22 '18 at 14:21

1

@nullpointer Thanks, fixed typo. Edited to use the added example in the question. So I'm proposing the OP change String properties to List<Predicate<CustomObject>> based on those property names.

– ernest_k
Nov 22 '18 at 14:37

add a comment |

You can just use a list of Predicates. Each of the following predicates tests one of the properties for equality against "".

List<Predicate<CustomObject>> propertiesCheckers = 

        Arrays.asList(pdo -> "".equals(pdo.get("prop1")),

            pdo -> "".equals(pdo.get("prop2")),

            pdo -> "".equals(pdo.get("prop3")));

And this stream checks each element against the predicate, returning true when the first empty value is found:

boolean anyEmpty = listOfObjects.stream()

        .flatMap(ob -> propertiesCheckers.stream().map(pred -> pred.test(ob)))

        .anyMatch(b -> b); //returns true if any "".equals returned true



if(anyEmpty) System.out.println("Some of the required fields are empty");

edited Nov 22 '18 at 14:34

answered Nov 22 '18 at 14:03

ernest_k

23.4k42649

You can just use a list of Predicates. Each of the following predicates tests one of the properties for equality against "".

List<Predicate<CustomObject>> propertiesCheckers = 

        Arrays.asList(pdo -> "".equals(pdo.get("prop1")),

            pdo -> "".equals(pdo.get("prop2")),

            pdo -> "".equals(pdo.get("prop3")));

And this stream checks each element against the predicate, returning true when the first empty value is found:

boolean anyEmpty = listOfObjects.stream()

        .flatMap(ob -> propertiesCheckers.stream().map(pred -> pred.test(ob)))

        .anyMatch(b -> b); //returns true if any "".equals returned true



if(anyEmpty) System.out.println("Some of the required fields are empty");

edited Nov 22 '18 at 14:34

answered Nov 22 '18 at 14:03

ernest_k

23.4k42649

edited Nov 22 '18 at 14:34

answered Nov 22 '18 at 14:03

ernest_k

23.4k42649

answered Nov 22 '18 at 14:03

ernest_k

23.4k42649

answered Nov 22 '18 at 14:03

ernest_k

23.4k42649

1. Though honestly, I am not very sure if I understand the question right. But, does this not miss the relation between the String properties in the question to the List<CustomObejct> listOfObjects somewhere? 2. There is also a typo in your checkers left with emp.

– nullpointer
Nov 22 '18 at 14:21

1

@nullpointer Thanks, fixed typo. Edited to use the added example in the question. So I'm proposing the OP change String properties to List<Predicate<CustomObject>> based on those property names.

– ernest_k
Nov 22 '18 at 14:37

add a comment |

1. Though honestly, I am not very sure if I understand the question right. But, does this not miss the relation between the String properties in the question to the List<CustomObejct> listOfObjects somewhere? 2. There is also a typo in your checkers left with emp.

– nullpointer
Nov 22 '18 at 14:21

1

@nullpointer Thanks, fixed typo. Edited to use the added example in the question. So I'm proposing the OP change String properties to List<Predicate<CustomObject>> based on those property names.

– ernest_k
Nov 22 '18 at 14:37

1. Though honestly, I am not very sure if I understand the question right. But, does this not miss the relation between the String properties in the question to the List<CustomObejct> listOfObjects somewhere? 2. There is also a typo in your checkers left with emp.

– nullpointer
Nov 22 '18 at 14:21

@nullpointer Thanks, fixed typo. Edited to use the added example in the question. So I'm proposing the OP change String properties to List<Predicate<CustomObject>> based on those property names.

– ernest_k
Nov 22 '18 at 14:37

add a comment |

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