How to create an array of objects(Key, value pair) in java servlet class

Question

I want to send data(array of objects) from java servlet to JavaScript.

Data should be in below format:

[
    {
        deviceId: 'TestDevice_001',
        deviceName: 'D_01',
        count: 1,
        expirationDate: '05/31/2021',
    },
    {
        deviceId: 'TestDevice_002',
        deviceName: 'D_02',
        Count: 5,
        expirationDate: '11/23/2024',
    },
    {
        deviceId: 'TestDevice_003',
        deviceName: 'D_03',
        Count: 4,
        expirationDate: '07/12/2022',
    },
]

I tried this by taking multiple arrays:

arr = ["deviceId", "deviceName", "count", "expirationDate"]

and insert records in extra arrays like:

 arr1 = ["TestDevice_001", "D_01", 1, "05/31/2021"]
 arr2 = ["TestDevice_002", "D_02", 5, "11/23/2024"]
 arr3 = same above format for 3rd record

After getting this data, tried to use hash map and other methods but failed. Also, above approach is really bad to use as I am creating multiple arrays for each records because if have to insert 50 records then have to create 50 arrays.

Can someone please help me here, what approach and how to convert the data into array of objects in above format in java servlet and send to JavaScript.

Answer 1

You can define a class for the elements of the array. You can also use Map<String,?> where the key is the name of the field.

Build each object, then put them in an array or a List, then convert that (the array or the list) to JSON.

That's it