Avoiding an unchecked cast for deepcopying map












0















I'm trying to implement a deepCopy method for a multi valued map like this:



public static <K, V> ListValuedMap<K, V> deepCopy (ListValuedMap<K, V> a) {
ListValuedMap<K, V> result = new ArrayListValuedHashMap<>();
a.asMap().forEach((key, value) -> {
Object newValue;
if (value instanceof ListValuedMap) {
newValue = deepCopy((ListValuedMap<K, V>) value);
‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
unchecked cast!

} else if (value instanceof Cloneable) {
try {
Method clone = value.getClass().getDeclaredMethod("clone");
newValue = clone.invoke(value);
} catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
throw new RuntimeException(e);
}
} else {
newValue = value;
}
result.put(key, (V) newValue);
‾‾‾
unchecked cast !
});
return result;
}


The second Unchecked cast can be avoided by passing the class for the V value type paramater argument and using vClass.cast(newValue), but I have no idea on how to procede for the first error.










share|improve this question























  • The first can be avoided by using <?,?>. The second cannot be avoided. Suppress it.

    – Michael
    Nov 16 '18 at 10:39











  • @Michael it's the other way around, the second maybe avoided using a class.cast the first one I cant see how

    – Vinz243
    Nov 16 '18 at 10:43











  • If you think the second can be avoided, why did you ask the question about it? It can't by the way.

    – Michael
    Nov 16 '18 at 10:45











  • result.put(key, vClass.cast(newValue)); doens't throw anything

    – Vinz243
    Nov 16 '18 at 10:46











  • You can't get V's class.

    – Michael
    Nov 16 '18 at 10:47
















0















I'm trying to implement a deepCopy method for a multi valued map like this:



public static <K, V> ListValuedMap<K, V> deepCopy (ListValuedMap<K, V> a) {
ListValuedMap<K, V> result = new ArrayListValuedHashMap<>();
a.asMap().forEach((key, value) -> {
Object newValue;
if (value instanceof ListValuedMap) {
newValue = deepCopy((ListValuedMap<K, V>) value);
‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
unchecked cast!

} else if (value instanceof Cloneable) {
try {
Method clone = value.getClass().getDeclaredMethod("clone");
newValue = clone.invoke(value);
} catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
throw new RuntimeException(e);
}
} else {
newValue = value;
}
result.put(key, (V) newValue);
‾‾‾
unchecked cast !
});
return result;
}


The second Unchecked cast can be avoided by passing the class for the V value type paramater argument and using vClass.cast(newValue), but I have no idea on how to procede for the first error.










share|improve this question























  • The first can be avoided by using <?,?>. The second cannot be avoided. Suppress it.

    – Michael
    Nov 16 '18 at 10:39











  • @Michael it's the other way around, the second maybe avoided using a class.cast the first one I cant see how

    – Vinz243
    Nov 16 '18 at 10:43











  • If you think the second can be avoided, why did you ask the question about it? It can't by the way.

    – Michael
    Nov 16 '18 at 10:45











  • result.put(key, vClass.cast(newValue)); doens't throw anything

    – Vinz243
    Nov 16 '18 at 10:46











  • You can't get V's class.

    – Michael
    Nov 16 '18 at 10:47














0












0








0








I'm trying to implement a deepCopy method for a multi valued map like this:



public static <K, V> ListValuedMap<K, V> deepCopy (ListValuedMap<K, V> a) {
ListValuedMap<K, V> result = new ArrayListValuedHashMap<>();
a.asMap().forEach((key, value) -> {
Object newValue;
if (value instanceof ListValuedMap) {
newValue = deepCopy((ListValuedMap<K, V>) value);
‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
unchecked cast!

} else if (value instanceof Cloneable) {
try {
Method clone = value.getClass().getDeclaredMethod("clone");
newValue = clone.invoke(value);
} catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
throw new RuntimeException(e);
}
} else {
newValue = value;
}
result.put(key, (V) newValue);
‾‾‾
unchecked cast !
});
return result;
}


The second Unchecked cast can be avoided by passing the class for the V value type paramater argument and using vClass.cast(newValue), but I have no idea on how to procede for the first error.










share|improve this question














I'm trying to implement a deepCopy method for a multi valued map like this:



public static <K, V> ListValuedMap<K, V> deepCopy (ListValuedMap<K, V> a) {
ListValuedMap<K, V> result = new ArrayListValuedHashMap<>();
a.asMap().forEach((key, value) -> {
Object newValue;
if (value instanceof ListValuedMap) {
newValue = deepCopy((ListValuedMap<K, V>) value);
‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
unchecked cast!

} else if (value instanceof Cloneable) {
try {
Method clone = value.getClass().getDeclaredMethod("clone");
newValue = clone.invoke(value);
} catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
throw new RuntimeException(e);
}
} else {
newValue = value;
}
result.put(key, (V) newValue);
‾‾‾
unchecked cast !
});
return result;
}


The second Unchecked cast can be avoided by passing the class for the V value type paramater argument and using vClass.cast(newValue), but I have no idea on how to procede for the first error.







java unchecked






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 16 '18 at 10:17









Vinz243Vinz243

4,18453169




4,18453169













  • The first can be avoided by using <?,?>. The second cannot be avoided. Suppress it.

    – Michael
    Nov 16 '18 at 10:39











  • @Michael it's the other way around, the second maybe avoided using a class.cast the first one I cant see how

    – Vinz243
    Nov 16 '18 at 10:43











  • If you think the second can be avoided, why did you ask the question about it? It can't by the way.

    – Michael
    Nov 16 '18 at 10:45











  • result.put(key, vClass.cast(newValue)); doens't throw anything

    – Vinz243
    Nov 16 '18 at 10:46











  • You can't get V's class.

    – Michael
    Nov 16 '18 at 10:47



















  • The first can be avoided by using <?,?>. The second cannot be avoided. Suppress it.

    – Michael
    Nov 16 '18 at 10:39











  • @Michael it's the other way around, the second maybe avoided using a class.cast the first one I cant see how

    – Vinz243
    Nov 16 '18 at 10:43











  • If you think the second can be avoided, why did you ask the question about it? It can't by the way.

    – Michael
    Nov 16 '18 at 10:45











  • result.put(key, vClass.cast(newValue)); doens't throw anything

    – Vinz243
    Nov 16 '18 at 10:46











  • You can't get V's class.

    – Michael
    Nov 16 '18 at 10:47

















The first can be avoided by using <?,?>. The second cannot be avoided. Suppress it.

– Michael
Nov 16 '18 at 10:39





The first can be avoided by using <?,?>. The second cannot be avoided. Suppress it.

– Michael
Nov 16 '18 at 10:39













@Michael it's the other way around, the second maybe avoided using a class.cast the first one I cant see how

– Vinz243
Nov 16 '18 at 10:43





@Michael it's the other way around, the second maybe avoided using a class.cast the first one I cant see how

– Vinz243
Nov 16 '18 at 10:43













If you think the second can be avoided, why did you ask the question about it? It can't by the way.

– Michael
Nov 16 '18 at 10:45





If you think the second can be avoided, why did you ask the question about it? It can't by the way.

– Michael
Nov 16 '18 at 10:45













result.put(key, vClass.cast(newValue)); doens't throw anything

– Vinz243
Nov 16 '18 at 10:46





result.put(key, vClass.cast(newValue)); doens't throw anything

– Vinz243
Nov 16 '18 at 10:46













You can't get V's class.

– Michael
Nov 16 '18 at 10:47





You can't get V's class.

– Michael
Nov 16 '18 at 10:47












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