Get rid of your nested if operators!

Every one of you know how it is disappointing that you can not use

switch

operators with strings, doubles, your custom objects, etc. But anyway sometimes it is possible to get rid of your nested ifs if you will use static maps. Let us consider an example: here we need to set JavaBean properties of certain types:

 protected static Object fillTestBean(Object bean) throws InvocationTargetException, IllegalArgumentException, IllegalAccessException {
  Method[] methods = bean.getClass().getMethods();

  for (Method method : methods) {
   if (RTTIUtils.isSetter(method)) {
    Class type = RTTIUtils.getSetterType(method);
    if (type == String.class)
     RTTIUtils.invokeSetter(bean, method, testStr);
    else if (type == boolean.class)
     RTTIUtils.invokeSetter(bean, method, testBoolean);
    else if (type == byte.class)
     RTTIUtils.invokeSetter(bean, method, testByte);
    else if (type == char.class)
     RTTIUtils.invokeSetter(bean, method, testChar);
    else if (type == short.class)
     RTTIUtils.invokeSetter(bean, method, testShort);
    else if (type == int.class)
     RTTIUtils.invokeSetter(bean, method, testInt);
    else if (type == long.class)
     RTTIUtils.invokeSetter(bean, method, testLong);
    else if (type == float.class)
     RTTIUtils.invokeSetter(bean, method, testFloat);
    else if (type == double.class)
     RTTIUtils.invokeSetter(bean, method, testDouble);
    else if (type == Boolean.class)
     RTTIUtils.invokeSetter(bean, method, testBooleanObj);
    else if (type == Byte.class)
     RTTIUtils.invokeSetter(bean, method, testByteObj);
    else if (type == Character.class)
     RTTIUtils.invokeSetter(bean, method, testCharacterObj);
    else if (type == Short.class)
     RTTIUtils.invokeSetter(bean, method, testShortObj);
    else if (type == Integer.class)
     RTTIUtils.invokeSetter(bean, method, testIntegerObj);
    else if (type == Long.class)
     RTTIUtils.invokeSetter(bean, method, testLongObj);
    else if (type == Float.class)
     RTTIUtils.invokeSetter(bean, method, testFloatObj);
    else if (type == Double.class)
     RTTIUtils.invokeSetter(bean, method, testDoubleObj);
    else if (type == Date.class)
     RTTIUtils.invokeSetter(bean, method, testDate);
   }
  }

  return bean;
 }

(here all variables starting with test are constants)
Seems really annoying to write all this ifs and, also what if we will need to check values? Another function will also need this nested ifs!
In this case I usually do the following (factory method -like solution):

 private static final Map initObjects = new HashMap();
 private static boolean isCosideredType(Class type) {
  return initObjects.containsKey(type);
 }
 static {
  initObjects.put(String.class, testStr);
  initObjects.put(boolean.class, testBoolean);
  initObjects.put(byte.class, testByte);
  initObjects.put(char.class, testChar);
  initObjects.put(short.class, testShort);
  initObjects.put(int.class, testInt);
  initObjects.put(long.class, testLong);
  initObjects.put(float.class, testFloat);
  initObjects.put(double.class, testDouble);
  initObjects.put(Boolean.class, testBooleanObj);
  initObjects.put(Byte.class, testByteObj);
  initObjects.put(Character.class, testCharacterObj);
  initObjects.put(Short.class, testShortObj);
  initObjects.put(Integer.class, testIntegerObj);
  initObjects.put(Long.class, testLongObj);
  initObjects.put(Float.class, testFloatObj);
  initObjects.put(Double.class, testDoubleObj);
  initObjects.put(Date.class, testDate);
 }

 protected static Object fillTestBean(Object bean) throws InvocationTargetException, IllegalArgumentException, IllegalAccessException {
  Method[] methods = bean.getClass().getMethods();

  for (Method method : methods) {
   if (RTTIUtils.isSetter(method)) {
    Class type = RTTIUtils.getSetterType(method);
    if (isCosideredType(type)) {
     RTTIUtils.invokeSetter(bean, method, initObjects.get(type));
    }
   }
  }

  return bean;
 }

Author: Artem's Blog

Working on software and more... View all posts by Artem's Blog