Use asList to create a list from array

Docs > Code Analysis > Static Analysis Rules > Use asList to create a list from array

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Metadata

ID: java-best-practices/arrays-aslist

Language: Java

Severity: Warning

Category: Performance

Description

Using Arrays.asList is much faster and cleaner than creating an array by iterating over the values.

Non-Compliant Code Examples

class Main {
    public List<Integer> getListOfSomething() {
        List<Integer> myList = new ArrayList<>();
        Integer[] myArray = getArrayFromCall();
        
        foo();
        for (int i = 0; i < myArray.length; i++) {
            myList.add(myArray[i]);
        }
        return myList;
    }
}

class Main {
    public List<Integer> getListOfSomething() {
        Integer[] myArray = getArrayFromCall();
        List<Integer> myList = new ArrayList<>();
        foo();
        for (int i = 0; i < myArray.length; i++) {
            myList.add(myArray[i]);
        }
        return myList;
    }
}

Compliant Code Examples

class Main {
    public List<Integer> getListOfSomething() {
        Integer[] myArray = getArrayFromCall();
        return Arrays.asList(myArray);
    }
}