I want to compare 2 object as same class,i want to konw What's the difference between two filed of the object, for example,
public class Person{
private String name;
private int age;
......
}
Person person1 = new Person();
person1.setName("jim");
person2.setage(12);
Person person2 = new Person();
person2.setName("jason");
person2.setage(14);
public Map compare(person1,person2)?
tell me name is different and age is different?
Here is a method to do it with Reflection:
public class Test {
public static void main(String[] args) {
Person person1 = new Person();
person1.name = "Jack";
person1.age = 18;
person1.favoriteSuperhero = "Superman";
Person person2 = new Person();
person2.name = "Jack";
person2.age = 20;
person2.favoriteSuperhero = "Superman";
Map<String, List<Object>> uncommonTraits = getUncommonTraits(person1, person2);
for(Entry<String, List<Object>> entry : uncommonTraits.entrySet()){
System.out.println(entry.getKey() + ":\t" + entry.getValue());
}
}
private static Map<String, List<Object>> getUncommonTraits(Person p1, Person p2) {
Map<String, List<Object>> result = new HashMap<>();
for(Field field : Person.class.getDeclaredFields()){
try {
if(!(field.get(p1).equals(field.get(p2)))){
result.put(field.getName(), new ArrayList<Object>(Arrays.asList(field.get(p1), field.get(p2))));
}
} catch (IllegalArgumentException | IllegalAccessException e) {
e.printStackTrace();
}
}
return result;
}
}
class Person {
public String name;
public int age;
public String favoriteSuperhero;
}
Output:
age: [18, 20]
This is very resistant to changes: if you add a field to your Person class, you won't have to change anything. It is also a bazillion times less redundant than manually checking each field.
I have used public fields for ease of use.
null value is caught by the instanceof requirement in every Equals() implementation. It will just return false as it should.
Map.getName()ofgetAge()method that we haven't seen yet :) Are you sure you cannot create these methods, @SummerZeng ?