public class FloatTest {
   public static String A = "JerryTest";
FloatTest tool = new FloatTest();
  System.out.println(tool.A);
  Object classObject = FloatTest.class;
用下面的代码从class对象里打印出静态field的value：
FloatTest tool = new FloatTest();
System.out.println(tool.A); // approach1: print static field via one class instance
Object classObject = FloatTest.class;
Class<FloatTest> convert = (Class<FloatTest>)classObject;
Field[] fields = convert.getFields();
Field staticField = fields[0];
  try {
  System.out.println("static field value: " + staticField.get(tool)); // approach2: via class 
 } catch (IllegalArgumentException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 } catch (IllegalAccessException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 }