Simple java solution
java\nclass Solution {\n    public int[] getConcatenation(int[] nums) {\n        var ans = new int[nums.length * 2];\n        \n        for (var i = 0; i < nums
```java\nclass Solution {\n    public int[] getConcatenation(int[] nums) {\n        var ans = new int[nums.length * 2];\n        \n        for (var i = 0; i < nums.length; i++) {\n            ans[i] = ans[i + nums.length] = nums[i];\n        }\n        \n        return ans;\n    }\n}\n```
['Java']