Android-java- How to sort a list of objects by a certain value within the object

Follow this code to sort any ArrayList

Collections.sort(myList, new Comparator<EmployeeClass>(){    public int compare(EmployeeClass obj1, EmployeeClass obj2) {        // ## Ascending order        return obj1.firstName.compareToIgnoreCase(obj2.firstName); // To compare string values        // return Integer.valueOf(obj1.empId).compareTo(Integer.valueOf(obj2.empId)); // To compare integer values        // ## Descending order        // return obj2.firstName.compareToIgnoreCase(obj1.firstName); // To compare string values        // return Integer.valueOf(obj2.empId).compareTo(Integer.valueOf(obj1.empId)); // To compare integer values        }    });

You should use Comparable instead of a Comparator if a default sort is what your looking for.

See here, this may be of some help - When should a class be Comparable and/or Comparator?

Try this -

import java.util.ArrayList;import java.util.Collections;import java.util.List;public class TestSort {    public static void main(String args[]){        ToSort toSort1 = new ToSort(new Float(3), "3");        ToSort toSort2 = new ToSort(new Float(6), "6");        ToSort toSort3 = new ToSort(new Float(9), "9");        ToSort toSort4 = new ToSort(new Float(1), "1");        ToSort toSort5 = new ToSort(new Float(5), "5");        ToSort toSort6 = new ToSort(new Float(0), "0");        ToSort toSort7 = new ToSort(new Float(3), "3");        ToSort toSort8 = new ToSort(new Float(-3), "-3");        List<ToSort> sortList = new ArrayList<ToSort>();        sortList.add(toSort1);        sortList.add(toSort2);        sortList.add(toSort3);        sortList.add(toSort4);        sortList.add(toSort5);        sortList.add(toSort6);        sortList.add(toSort7);        sortList.add(toSort8);        Collections.sort(sortList);        for(ToSort toSort : sortList){            System.out.println(toSort.toString());        }    }}public class ToSort implements Comparable<ToSort> {    private Float val;    private String id;    public ToSort(Float val, String id){        this.val = val;        this.id = id;    }    @Override    public int compareTo(ToSort f) {        if (val.floatValue() > f.val.floatValue()) {            return 1;        }        else if (val.floatValue() <  f.val.floatValue()) {            return -1;        }        else {            return 0;        }    }    @Override    public String toString(){        return this.id;    }}

I think this will help you better

Person p = new Person("Bruce", "Willis");Person p1  = new Person("Tom", "Hanks");Person p2 = new Person("Nicolas", "Cage");Person p3 = new Person("John", "Travolta");ArrayList<Person> list = new ArrayList<Person>();list.add(p);list.add(p1);list.add(p2);list.add(p3);Collections.sort(list, new Comparator() {    @Override    public int compare(Object o1, Object o2) {        Person p1 = (Person) o1;        Person p2 = (Person) o2;        return p1.getFirstName().compareToIgnoreCase(p2.getFirstName());    }});