Question

I am trying to write a general method to parse objects from strings. To be clear, I have the following not-so-elegant implementation:

public static Object parseObjectFromString(String s, Class class) throws Exception {
  String className = class.getSimpleName();
  if(className.equals("Integer")) {
    return Integer.parseInt(s);
  }
  else if(className.equals("Float")) {
    return Float.parseFloat(s);
  }
  else if ...

}

Is there a better way to implement this?

Answer 1

Your method can have a single line of code:

public static <T> T parseObjectFromString(String s, Class<T> clazz) throws Exception {
    return clazz.getConstructor(new Class[] {String.class }).newInstance(s);
}

Testing with different classes:

Object obj1 = parseObjectFromString("123", Integer.class);
System.out.println("Obj: " + obj1.toString() + "; type: " + obj1.getClass().getSimpleName());
BigDecimal obj2 = parseObjectFromString("123", BigDecimal.class);
System.out.println("Obj: " + obj2.toString() + "; type: " + obj2.getClass().getSimpleName());
Object obj3 = parseObjectFromString("str", String.class);
System.out.println("Obj: " + obj3.toString() + "; type: " + obj3.getClass().getSimpleName());
Object obj4 = parseObjectFromString("yyyy", SimpleDateFormat.class);
System.out.println("Obj: " + obj4.toString() + "; type: " + obj4.getClass().getSimpleName());

The output:

Obj: 123; type: Integer
Obj: str; type: String
Obj: 123; type: BigDecimal
Obj: java.text.SimpleDateFormat@38d640; type: SimpleDateFormat