How do you sort an Arraylist of objects in Java?
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I have created an arraylist which stores objects. Each object consists of a name and age. How can I sort this arraylist in descending order of age?
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Answer:
Because of how ArrayLists behave, I would recommend a merge sort for this purpose. You can see the algorithm on Wikipedia. I could write the exact method if I knew the name and API of the class you're dealing with.
Maikol at Yahoo! Answers Visit the source
Other answers
Your Object has to implements Comparable which enforces the following contract public int compareTo( Object o ) throws ClassCastException { Person anotherPerson = (Person)o; return this.getAge() - anotherPerson.getAge(); } List<Person> persons = new ArrayList<Person>(); persons.add( new Person( "Billy Bob", 33 ) ); persons.add( new Person( "Squeeky Sue", 29) ); ... Collections.sort( persons ).reverse(); // to get your descending order. Note I use the interface List which implements Collections.
deonejuan
import java.util.*; Arrays.sort(objectArray, new Comperator<ABC>() { public int compare(ABC o1, ABC o2) { return o2.getAge() - o1.getAge(); } });
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