Example

public class TestClass {
char c = 'm';

void test () {
Character ch = 'L';
if (ch.isUpperCase(c)) {
return;
}
}


Solution
Avoid using an object (for example ch) to access the static method. Use the class name (for example Character) intead.

public class TestClass {
char c = 'm';

void test () {
if (Character.isUpperCase(c)) {
return;
}
}