CODEWITHSUNDEEP
javaarraysinitialization
leba-lev
leba-lev

Reputation: 2898

initializing a boolean array in java

I have this code

public static Boolean freq[] = new Boolean[Global.iParameter[2]];
freq[Global.iParameter[2]] = false;

could someone tell me what exactly i'm doing wrong here and how would i correct it? I just need to initialize all the array elements to Boolean false. thank you

Upvotes: 115

Views: 437471

Answers (7)

Harsh Yadav
Harsh Yadav

Reputation: 1

We can also use List collection to store boolean data:-

List<boolean>result=new List<>();
result.add(condition);
return result;

Upvotes: 0

Java wanna bee
Java wanna bee

Reputation: 3099

The main difference is that Boolean is an object and boolean is an primitive.

  • Object default value is null;
  • boolean default value is false;

Upvotes: 0

J&#248;rgen Fogh
J&#248;rgen Fogh

Reputation: 7646

The array will be initialized to false when you allocate it.

All arrays in Java are initialized to the default value for the type. This means that arrays of ints are initialised to 0, arrays of booleans are initialised to false and arrays of reference types are initialised to null.

Upvotes: 22

BalusC
BalusC

Reputation: 1108557

I just need to initialize all the array elements to Boolean false.

Either use boolean[] instead so that all values defaults to false:

boolean[] array = new boolean[size];

Or use Arrays#fill() to fill the entire array with Boolean.FALSE:

Boolean[] array = new Boolean[size];
Arrays.fill(array, Boolean.FALSE);

Also note that the array index is zero based. The freq[Global.iParameter[2]] = false; line as you've there would cause ArrayIndexOutOfBoundsException. To learn more about arrays in Java, consult this basic Oracle tutorial.

Upvotes: 315

Big Endian
Big Endian

Reputation: 954

Arrays in Java start indexing at 0. So in your example you are referring to an element that is outside the array by one.

It should probably be something like freq[Global.iParameter[2]-1]=false;

You would need to loop through the array to initialize all of it, this line only initializes the last element.

Actually, I'm pretty sure that false is default for booleans in Java, so you might not need to initialize at all.

Best Regards

Upvotes: 9

codaddict
codaddict

Reputation: 454920

They will be initialized to false by default. In Java arrays are created on heap and every element of the array is given a default value depending on its type. For boolean data type the default value is false.

Upvotes: 5

oneat
oneat

Reputation: 10994

public static Boolean freq[] = new Boolean[Global.iParameter[2]];

Global.iParameter[2]:

It should be const value

Upvotes: 2

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