Why am I getting the \'\'.class\' expected\' error in Java, and how can I fix it?

Understanding and Resolving the "'.class' Expected" Error

While compiling code in Java, developers may encounter the enigmatic error message "'.class' expected." This error can be puzzling for both beginners and experienced programmers alike. Let's delve into its meaning, causes, and effective remedies.

Meaning and Cause

The "'.class' expected" error arises when the compiler encounters a type (e.g., int, int[]) where it anticipates an expression. This odd behavior stems from the compiler's confusion during syntax checking, leading it to expect a class declaration after a period (.).

Examples

Here are some examples of the error:

double d = 1.9;
int i = int d;  // error here

int j = someFunction(int[] a);  // error here

In both cases, the compiler will complain with "error: '.class' expected."

Resolution

The unhelpful "suggestion" to add ".class" is almost always incorrect. Instead, the actual solution depends on the intended purpose of the type in the code:

1. Type Casting:

If the intention was to perform a type cast, enclose the type in parentheses:

double d = 1.9;
int i = (int) d;   // Correct: casts `1.9` to an integer

2. Variable Assignment or Parameter Passing:

Typically, types should be removed for simple assignment or parameter passing:

int j = someFunction(a);  // Correct ... assuming `a`'s type is suitable for the call

Additional Examples

Incorrect:

someMethod(array[]);

Correct:

someMethod(array);                  // pass ref to array
someMethod(array[someExpression]);  // pass array element

Incorrect:

int i = someMethod(int j); 

Correct:

int i = someMethod(j);

Incorrect:

int i = int(2.0);

Correct:

int i = (int) 2.0;

Incorrect:

int[]; letterCount = new int[26];

Correct:

int[] letterCount = new int[26];

Incorrect:

if (someArray[] > 80) {
    // ...
}

Correct:

if (someArray[someIndex] > 80)

Incorrect:

int[] integers = new int[arraySize];
...
return integers[];

Correct:

return integers;             // Return entire array
return integers[someIndex];  // Return array element

Incorrect:

if ((withdraw % 5 == 0) & (acnt_balc >= withdraw + 0.50))
    double cur = acnt_balc - (withdraw + 0.50);
    System.out.println(cur);
else
    System.out.println(acnt_balc);

Correct:

if ((withdraw % 5 == 0) & (acnt_balc >= withdraw + 0.50)) {
    double cur = acnt_balc - (withdraw + 0.50);
    System.out.println(cur);
} else {
    System.out.println(acnt_balc);
}

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