Java illegal expression

An illegal expression in Java is an expression that is not allowed by the syntax rules of the language. This can occur when an expression is written in an incorrect format or when it uses elements that are not allowed in the context in which it appears.

Here are a few examples of illegal expressions in Java:

• Using an undeclared variable:

int x = 10;
int y = x + z; // error: z is not declared

• Using an operator with the wrong number or type of operands:

int x = 10;
int y = x + "hello"; // error: cannot add int to String

• Using a method without the required arguments:

int max(int x, int y) {
  return x > y ? x : y;
}
int result = max(); // error: missing arguments

• Using a reserved word as an identifier:

int class = 10; // error: "class" is a reserved word

If you encounter an illegal expression error in your code, it is important to carefully review the expression and ensure that it follows the correct syntax and uses allowed elements. You may also need to check for spelling errors or typos.