You need a program written in Java.
Write a simple line editor. Keep the entire text in an ArrayList object, one line in a separate index position. Start the program with entering EDIT file, after which a prompt appears along with the line number.
If the letter I is entered with a number n following it, then insert the text to be followed on line n. If I is not followed by a number, then insert the text on the current line.
If D is entered with two numbers n and m,one n, or no number then delete lines nthrough m, line n, or the current line. Do the same with command L, which stands for listing lines.
If A is entered, then append the text to the existing lines or the last line. Entry E signifies exit and saving a text file.
Example:
Input file: textin.txt
The first line
And another line
EDIT testin
1>The first line
2>
3> And another line
4> I 3
3> The second line
4> One more line
5> L
1>The first line
2>
3> The second line
4> One more line
5> And another line // This is now line 5, not 3
5> D 2 // line 5, since L was issued form line 5
4> L // line 4, since one line was deleted
1>The first line
2> The second line
3> One more line
4> And another line
5>D 2 4
4>L
1>The first line
2>A
1> not done yet
2> L
1>The first line not done yet
2> E
Output File: textout.txt
The first line not done yet
The lines that are left or changed after entering E must be saved in new text file. textout.txt