删除数组的第一个元素而不使用 java

Question

i'm trying to read a line in a file and store it in an array, after doing this i want to remove the first element in the array so that the length can be 1 element less and make the length of the array same as another array so i can match both arrays using for loop. the line i want to read from the file is "London 2 7 24 16 -15 8 27"

try {
        File myObj = new File("temperatures.txt");
        FileReader read = new FileReader(myObj);
        Scanner myReader = new Scanner(myObj);
        Scanner input = new Scanner(System.in);
        LineNumberReader lines = new LineNumberReader(read);
        lines.skip(Long.MAX_VALUE);
        int len = lines.getLineNumber();
        int count = len;
        String ans;
        for (int i = 0; i < len && myReader.hasNextLine();i++){
            System.out.println(count+" Cities temperature left!");
            System.out.print("Do you want to check temperature details; enter y or n: ");
            ans = input.nextLine();
            if(ans.equals("y")){
                String[] getData = myReader.nextLine().split(" ");
                String[] days = {"Mon", "Tue", "Weds", "Thurs", "Fri", "Sat", "Sun"};
                for (int j = 0; j < getData.length; j++){
                    System.out.println(days[j]+": "+getData[j]);
                }

            }
            else{

            }
        }
    } catch (FileNotFoundException e) {
        System.out.println("An error occurred.");
        e.printStackTrace();
  }

Answer 1

Why not add +1 to the index value of getData[] in the loop?

System.out.println(days[j] + ": " +getData[j+1]);

Answer 2

There are several possible solutions to your problem.

1. Not deleting the element at all

You can iterate 2 arrays in parallel like this:

for (int j = 0; j < days.length; j++) {
    System.out.println(days[j] + ": " + getData[j + 1]);
}

As you can see, we start and index 0 with days , but we start at 1 with getData . This will work, because you know that getData is exactly one element bigger than days . Also, note that the condition of the loop changed to j < days.length . This is because days is shorter and so we should iterate through the shorter array. Alternatively, you can write j < getData.length - 1 .

2. Creating a copy

There is no way to delete an element from an array. You have to construct a new array.

String[] newData = new String[getData.length - 1];
for (int j = 0; j < newData.length; j++) {
    newData[j] = getData[j + 1];
}

Then you can use newData instead of getData to print the numbers.

3. Use a collection or a stream

I won't go into the details, but you can construct a collection (eg an ArrayList) from your array, delete the first element from the list (because unlike arrays, you can actually delete elements of lists), and then iterate the list (no need to create another array). Or, you can create a stream from an array, skip the first element (streams have the skip method), and copy the stream into an array.

But as for me, this way is overkill for such a simple task. I think that even creating a copy is a bit too much. You're better off just using the first solution, it's the easiest one.