char数组（Java）中的空单元格的值是什么？

Question

Please consider this scenario:

char[] array = new char[4];
array[0] = 'a';
array[1] = '3';
array[3] = 'q';

As you can see, array[2] was never 'filled' with anything. What would be the value of array[2] ?

What do I need to check for when iterating through a char array, looking for 'empty' cells?

Answer 1

array[2] will be populated with the null char literal . The value of which is \ .

char is a primitive type. This means that it can never hold null , so like int , double and the rest, it needs some starting value. For int it's 0 , for char it's \ , which actually evaluates to 0 .

You can view the starting values for primitive types here .

Answer 2

The answer is: (char)0.

Default values for primitives are 0, 0.0f, 0.0 (double), (char)0 and false (for boolean).

Applies to arrays and single variables.

Answer 3

In Java, char[] array = new char[4]; will set all the memory associated to that array to zero. In this case therefore each element will have the value of the null character literal '\\0' .

(This is not true for all languages, in C and C++, for example, the memory is unitialised and to access it before initialisation is, technically, undefined behaviour).

Answer 4

数组的空单元格始终为0，因为数组会自动由0初始化，因此它将为'0'

Answer 5

Like others already said, the default value will be null '\'. If you try to print it out, it will be an empty value. (Meaning you can't see it)