合并两个数组列表

Question

I have Two ArrayLists

1. ArrayList<Integer> data = new ArrayList<Integer>();
2. ArrayList<Integer> temp = new ArrayList<Integer>();

In the first array i have entries between 1-60(Some Numbers are Missing). In the second array are those missing numbers.

I want to print all entries Such as....

Which are present would apperar like 1 --- Y

And those which are missing would appers like 12 --- N

Here is my code:

writer=new PrintWriter(new FileWriter(file,true));
                    for(int i=1;i<60;i++){
                        for(int missing:temp){
                        if(missing==i){
                            writer.println(i+"   +++++++++++++++++   N");
                        }
                        else{
                            writer.println(i+"   ---   Y");
                        }
                    }
                }

but my output is like:

1 --- Y

1 --- Y

2 --- Y

2 --- Y and so on.....

Answer 1

You question seems a bit confusing... but you may want this:

for (int actual = 1; actual <= 60; actual ++) {
    // number present in DATA list
    if (data.contains(actual)) {
        writer.println(actual + "   ---   Y");
    // number present in TEMP list
    } else if (temp.contains(actual)) {
        writer.println(actual + "   ---   N");
    // number not present in ANY list
    } else {
        writer.println(actual + "   -------");
    }
}

---

OUTPUT:

1   ---   Y
2   ---   Y
3   ---   N
4   ---   Y
5   ---   Y
6   ---   Y
7   ---   N
8   ---   N
9   -------
10   -------
11   -------

And so on...

---

ADD ON's:

Remember to close the writer:

writer.close();

In the way you use FileWritter , content will be appended at the end of the file, use false in the constructor:

PrintWriter writer = new PrintWriter(new FileWriter(file, false));

---

TEST IT!

public class Q37024973 {
    public static void main(String[] args) throws Exception {
        ArrayList<Integer> data = new ArrayList<Integer>();
        data.add(1);
        data.add(2);
        data.add(4);
        data.add(5);
        data.add(6);
        ArrayList<Integer> temp = new ArrayList<Integer>();
        temp.add(3);
        temp.add(7);
        temp.add(8);

        File file = new File("C:\\tmp\\Q37024973.txt");

        PrintWriter writer = new PrintWriter(new FileWriter(file, true));

        for (int actual = 1; actual <= 60; actual ++) {
            if (data.contains(actual)) {
                writer.println(actual + "   ---   Y");
            } else if (temp.contains(actual)) {
                writer.println(actual + "   ---   N");
            } else {
                writer.println(actual + "   -------");
            }
        }

        writer.close();
    }
}

Answer 2

Replace Your Code With:

writer=new PrintWriter(new FileWriter(file,true));
    for(int i=1;i<=60;i++){
        if(temp.contains(i)){
            writer.println(i+"   +++++++++++++++++   N");
        }
        else{
            writer.println(i+"   ---   Y");
    }
}

Answer 3

1. You are not using your data list - why are you mentioning it at all in your question? You probably suppose that each number is exactly in one of the lists. As you already mentioned this list, I will write you a code which uses it.

2. Nomen omen aka use better meaningful names. data and temp are not very eloquent names.

3. Always declare lists as List , do not use the specification.

4. You say "numbers 1-60", but your for-loop has upper limit < 60 .

5. Use Java 7 feature "try-with-resources", this will ensure that your writer is consistently closed.

Now the code snippet:

List<Integer> existingNumbers = new ArrayList<>();
List<Integer> missingNumbers = new ArrayList<>();

try (Writer writer = new PrintWriter(new FileWriter(file,true))) {
    for (int i=1; i<=60; i++) {
        if (missingNumbers.contains(i)) {
            writer.println(i+"   ---   N");
        }
        if (existingNumbers.contains(i)) {
            writer.println(i+"   ---   Y");
        }
    }
}

Answer 4

Here is a different approach based on your description (note that the example modifies the data object):

List<Integer> data = new ArrayList();
data.add(1);
data.add(2);
data.add(4);

List<Integer> temp = new ArrayList();
temp.add(3);
temp.add(5);

data.addAll(temp);
Collections.sort(data); //do you want sorting?

for(Integer i : data){
    if(temp.contains(i)){
        System.out.println(i+" --- Y");
    }
    else{
        System.out.println(i+" ---- N");
    }
}