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How to unpack an array into different arguments on method call

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误落风尘
误落风尘 2021-02-14 02:31

I would like to know if it is possible to unpack an Object array into separate Object on method call which accepts vargs. This question is similar to this one.

I have a

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  • 陌清茗
    陌清茗 (楼主)
    2021-02-14 03:22

    Well, there is no syntactic sugar à la Python or Lua for that in Java, but you can create your own unpack method:

    @SafeVarargs
public static  Object[] unpack(E... objects) {
    List list = new ArrayList();
    for (Object object : objects) {
        if (object instanceof Object[]) {
            list.addAll(Arrays.asList((Object[]) object));
        }
        else{
            list.add(object);
        }
    }

    return list.toArray(new Object[list.size()]);
}



    This will returns an array containing all the input elements, unpacked.
    


    Then you can call it in your main method:
    


    res = doWork(unpack("three", res));

    


    The reason I make this method generic is that you can call it with, for example, a String[] array, without generating a warning. For some reason, the Java compiler thinks that this method has a chance of "polluting the heap", but it is not the case, that's why I added a @SafeVarargs annotation.
    
    
    
             
    
                                                        
    
            
            
    
              
                
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