It is acceptable to compare the float value to the char variable c. : Comparison Operators « Operators « SCJP

1. SCJP
2. Operators
3. Comparison Operators

Java promotes the smaller type to the larger type; 
char value A (represented by the Unicode value 65) is promoted to a float 65.0F. 
The comparison is then performed on the resulting float values.

public class MainClass {
  public static void main(String[] argv) {
    char a = 'A';
    float f = 100.11F;
    if (a > f) {
      System.out.println("a > f");
    }

  }
}