How to initialize all the elements of an array to any specific value in java
JavaArraysJava Problem Overview
In C/C++ we have memset() function which can fulfill my wish but in Java how can i initialize all the elements to a specific value? Whenever we write int[] array=new int[10]; , this simply initialize an array of size 10 having all elements equal to zero. I just want to change this initialization integer for one of my array. i.e. I want to initialize an array which has all elements equal to -1. Otherwise I have to put a for loop just after initialization, which ranges from index 0 to index size-1 and inside that loop, I am assigning element to -1. Below is the code for more understanding-
int[] array = new int[10];
for (int i = 0; i < size; i++) {
array[i] = -1;
}
Am i going correct? Is there any other way for the same?
Java Solutions
Solution 1 - Java
If it's a primitive type, you can use Arrays.fill():
Arrays.fill(array, -1);
[Incidentally, memset in C or C++ is only of any real use for arrays of char.]
Solution 2 - Java
There's also
int[] array = {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1};
Solution 3 - Java
It is also possible with Java 8 streams:
int[] a = IntStream.generate(() -> value).limit(count).toArray();
Probably, not the most efficient way to do the job, however.
Solution 4 - Java
You could do this if it's short:
int[] array = {-1,-1,-1,-1,-1,-1,-1,-1,-1,-1};
but that gets bad for more than just a few.
Easier would be a for loop:
int[] myArray = new int[10];
for (int i = 0; i < array.length; i++)
myArray[i] = -1;
Edit: I also like the Arrays.fill() option other people have mentioned.
Solution 5 - Java
Solution 6 - Java
Have you tried the Arrays.fill function?
Solution 7 - Java
You can use Arrays.fill(array, -1).
Solution 8 - Java
Evidently you can use Arrays.fill(), The way you have it done also works though.
Solution 9 - Java
Using Java 8, you can simply use ncopies of Collections class:
Object[] arrays = Collections.nCopies(size, object).stream().toArray();
In your case it will be:
Integer[] arrays = Collections.nCopies(10, Integer.valueOf(1)).stream().toArray(Integer[]::new);
.
Here is a detailed answer of a similar case of yours.
Solution 10 - Java
For Lists you can use
Collections.fill(arrayList, "-")
Solution 11 - Java
Arrays class in java.utils has a method for that.
Arrays.fill(your_array, value_to_fill);