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I am creating an ArrayList and its size is 40
ArrayList<Integer> myList= new ArrayList<>(40);
How can I initialize myList with zeros 0 ? I tried this
for(int i=0; i<40; i++){
myList.set(i, 0);
}
but I get
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
969
Using default values in initialization of array For double or float , the default value is 0.0 , and the default value is null for string. Type[] arr = new Type[capacity]; For example, the following code creates a primitive integer array of size 5 . The array will be auto-initialized with a default value of 0 .
To initialize an arraylist in single line statement, get all elements in form of array using Arrays. asList method and pass the array argument to ArrayList constructor. ArrayList<String> names = new ArrayList<String>( Arrays.
If your breakpoint is on the initialization line, that line has note yet executed and the value will still be null. The breakpoint is after that line is executed, and that's where it's showing as null . And no, it is not being reinitialized as null later.
Exactly as arrays in all C-like languages. The indexes start from 0.
Java: Initialize list with zeroes. Here's how: List<Integer> list = Collections.nCopies(1337 Desired number of zeroes, 0); Note that nCopies returns an immutable list. To initialize for instance an ArrayList, use this: List<Integer> list = new ArrayList<Integer>(Collections.nCopies(1337, 0));
An array is initialized to 0 if the initializer list is empty or 0 is specified in the initializer list. The declaration is as given below: The most simple technique to initialize an array is to loop through all the elements and set them as 0. Video Player is loading. This is a modal window. Beginning of dialog window.
Show activity on this post. How can I initialize myList with zeros 0 ? I tried this Show activity on this post. You can use Collections.fill (List<? super T> list,T obj) method to fill your list with zeros. In your case you are setting new ArrayList<> (40) here 40 is not length of the list but the initial capacity.
Note that nCopies returns an immutable list. To initialize for instance an ArrayList, use this: List<Integer> list = new ArrayList<Integer> (Collections.nCopies (1337, 0));
You can use Collections.fill(List<? super T> list,T obj) method to fill your list with zeros. In your case you are setting new ArrayList<>(40) here 40 is not length of the list but the initial capacity. You can use array to build your list with all zeros in it. Checkout following piece of code.
ArrayList<Integer> myList= new ArrayList<>(Arrays.asList(new Integer[40]));
Collections.fill(myList, 0);//fills all 40 entries with 0"
System.out.println(myList);
OUTPUT
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
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