How to initialize an array in Java?

data[10] = {10,20,30,40,50,60,71,80,90,91};

The above is not correct (syntax error). It means you are assigning an array to data[10] which can hold just an element.

If you want to initialize an array, try using Array Initializer:

int[] data = {10,20,30,40,50,60,71,80,90,91};

// or

int[] data;
data = new int[] {10,20,30,40,50,60,71,80,90,91};

Notice the difference between the two declarations. When assigning a new array to a declared variable, new must be used.

Even if you correct the syntax, accessing data[10] is still incorrect (You can only access data[0] to data[9] because index of arrays in Java is 0-based). Accessing data[10] will throw an ArrayIndexOutOfBoundsException.

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Try

data = new int[] {10,20,30,40,50,60,71,80,90,91 };

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When you create an array of size 10 it allocated 10 slots but from 0 to 9. This for loop might help you see that a little better.

public class Array {
    int[] data = new int[10]; 
    /** Creates a new instance of an int Array */
    public Array() {
        for(int i = 0; i < data.length; i++) {
            data[i] = i*10;
        }
    }
}

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You can do:

int[] data = {10,20,30,40,50,60,71,80,90,91};

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Syntax

 Datatype[] variable = new Datatype[] { value1,value2.... }

 Datatype variable[]  = new Datatype[] { value1,value2.... }

Example :

int [] points = new int[]{ 1,2,3,4 };

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*You can find Initialization as well as declaration with full description *

int n; // size of array here 10
int[] a = new int[n];
for (int i = 0; i < a.length; i++)
{
    a[i] = Integer.parseInt(s.nextLine()); // using Scanner class
}

Input: 10//array size 10 20 30 40 50 60 71 80 90 91

Displaying data:

for (int i = 0; i < a.length; i++) 
{
    System.out.println(a[i] + " ");
}

Output: 10 20 30 40 50 60 71 80 90 91

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You cannot initialize an array like that. In addition to what others have suggested, you can do :

data[0] = 10;
data[1] = 20;
...
data[9] = 91;

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you are trying to set the 10th element of the array to the array try

data = new int[] {10,20,30,40,50,60,71,80,90,91};

FTFY

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If you want to initialize an array in a constructor, you can't use those array initializer like.

data= {10,20,30,40,50,60,71,80,90,91};

Just change it to

data = new int[] {10,20,30,40,50,60,71,80,90,91};

You don't have to specify the size with data[10] = new int[] { 10,...,91} Just declare the property / field with int[] data; and initialize it like above. The corrected version of your code would look like the following:

public class Array {

    int[] data;

    public Array() {
        data = new int[] {10,20,30,40,50,60,71,80,90,91};
    }

}

As you see the bracket are empty. There isn't any need to tell the size between the brackets, because the initialization and its size are specified by the count of the elements between the curly brackets.

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Maybe this will work:

public class Array {

    int data[] = new int[10]; 
    /* Creates a new instance of Array */
    public Array() {
        data= {10,20,30,40,50,60,71,80,90,91};
    }
}

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