CODEWITHSUNDEEP
javaarrays
Braum Holdren
Braum Holdren

Reputation: 35

Inserting an Element into an array while moving items to the right

So let's say I have an array: {5, 7, 8, 9, 10}. However, I want to insert an element so that the array becomes {5, 6, 7, 8, 9} inserting 6 between 5 and 7, moving 10 out and shifting 9 to the right.

How do I use arrays and for loops to solve this problem?

Upvotes: 3

Views: 54

Answers (1)

rzwitserloot
rzwitserloot

Reputation: 103893

arrays are extremely low-level constructs that do not have methods that do this for you. ArrayList does which should be used for such a job.

If, as purely an academic exercise which should never make it to production, you are intrigued as to how the authors of ArrayList make such a thing:

By.. just.. doing it.

Break down the steps and perform them all.

Starting state: [5, 7, 8, 9, 10]
 Desired state: [5, 6, 7, 8, 9 ]

In other words, We need to copy 7/8/9 into new positions to make room. Once that is done, we can write the 6.

int[] in = {5, 7, 8, 9, 10};
// Copy starting from index 1 (second number)
// Copy into the same array, at index 2.
// ... and copy 3 numbers.
System.arraycopy(in, 1, in, 2, 3);
System.out.println(Arrays.toString(in));
// Prints: [5, 7, 7, 8, 9].
in[1] = 6;
System.out.println(Arrays.toString(in));
// Prints: [5, 6, 7, 8, 9].

Upvotes: 2

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