Use Java to complete the program

E7.20 Consider the following class: public class Sequence { private ArrayList values; public Sequence() { values = new ArrayList(); } public void add (int n) { values.add(n); } public String toString() { return values.toString(); } } = Add a method public Sequence append(Sequence other) that creates a new sequence, appending this and the other sequence, without modify- ing either sequence. For example, if a is 1 4 9 16 and bis the sequence 9 7 4 9 11 then the call a.append(b) returns the sequence 1 4 9 16 9 7 4 9 11 without modifying a or b. - E7.21 Add a method public Sequence merge(Sequence other) to the sequence class of Exercise E7.20 that merges two sequences, alternating ele- ments from both sequences. If one sequence is shorter than the other, then alternate as long as you can and then append the remaining elements from the longer sequence. For example, if a is 1 4 9 16 and bis 9 7 4 9 11 then a.merge(b) returns the sequence 1 9 4 7 9 4 16 9 11 without modifying a or b. - E7.22 Add a method public sequence mergeSorted (Sequence other) to the sequence class of Exercise E7.20 that merges two sorted sequences, producing a new sorted sequence. Keep an index into each sequence, indicating how much of it has been processed already. Each time, append the smallest unprocessed value from either sequence, then advance the index. For example, if a is 1 4 9 16 and bis 4 7 9 9 11 then a. merge Sorted(b) returns the sequence 1 4 4 7 9 9 9 11 16 If a orbis not sorted, merge the longest prefixes of a and b that are sorted