Question: In my assignment the third step is to Call the method merge to merge the two lists in list1 so that the list1 **remains sorted.**

I write my code but it doesn't work well , the output show wrong because it important to be sorted 

```
 public static void merge (ArrayList<Integer> list1, ArrayList<Integer> list2)
 {
        int i;
        int n=list1.size();
        int pos , j=0;

        for (pos =0 ;pos<n ; pos++)
        {
            for ( i=0 ; i<n ; i++)
                if (list1.get(j)>list2.get(pos))
                    list1.add(pos,list2.get(pos));
                else 
                    j++;
       } 
 }

```

Answer: 
You only need one `for` loop assuming both lists are sorted: 

```
public static void merge(List<Integer> l1, List<Integer> l2) {
    for (int index1 = 0, index2 = 0; index2 < l2.size(); index1++) {
        if (index1 == l1.size() || l1.get(index1) > l2.get(index2)) {
            l1.add(index1, l2.get(index2++));
        }
    }
}  

```

If `l2` isn't sorted, you need two loops: 

```
public static void merge(List<Integer> l1, List<Integer> l2) {
    for (int index2 = 0; index2 < l2.size(); index2++) {
        for (int index1 = 0; ; index1++) {
            if (index1 == l1.size() || l1.get(index1) > l2.get(index2)) {
                l1.add(index1, l2.get(index2));
                break;
            }
        }
    }
}

```
```
public static void merge (ArrayList<Integer> list1, ArrayList<Integer> list2)
{
    list1.addAll(list2);
    Collections.sort(list1);
}

```