Java ArrayList sort examples use of Comparator interface

Example 01

 package CollectionFramework;  
 import java.util.ArrayList;  
 import java.util.Collections;  
 import java.util.Comparator;  
 import java.util.Iterator;  
 import java.util.List;  
 public class ArrayLists {  
      public static void main(String[] args) {  
           Students student1 = new Students("John", "two", "abc", 12);  
           Students student2 = new Students("Allen", "two", "abc", 12);  
           Students student3 = new Students("bob", "three", "abc", 15);  
           Students student4 = new Students("amanda", "Four", "abc", 16);  
           Students student5 = new Students("Dave", "five", "abc", 16);  
           List<Students> studentList = new ArrayList<Students>();  
           studentList.add(student1);  
           studentList.add(student2);  
           studentList.add(student3);  
           studentList.add(student4);  
           studentList.add(student5);  
           studentList.add(new Students("sudas", "twelve", "XyZ", 21));  
           // studentList.sort(null);  
           Collections.sort(studentList, new Comparator<Students>() {  
                @Override  
                public int compare(Students o1, Students o2) {  
                     return o1.getName().compareToIgnoreCase(o2.getName());  
                }  
           });  
           Iterator<Students> sList = studentList.iterator();  
           while (sList.hasNext()) {  
                System.out.println(sList.next().getName());  
           }  
      }  
 }  
 class Students {  
      String name;  
      String grade;  
      String address;  
      int age;  
      public Students(String name, String grade, String address, int age) {  
           this.name = name;  
           this.grade = grade;  
           this.address = address;  
           this.age = age;  
      }  
      public String getName() {  
           return name;  
      }  
      public void setName(String name) {  
           this.name = name;  
      }  
      public String getGrade() {  
           return grade;  
      }  
      public void setGrade(String grade) {  
           this.grade = grade;  
      }  
      public String getAddress() {  
           return address;  
      }  
      public void setAddress(String address) {  
           this.address = address;  
      }  
      public int getAge() {  
           return age;  
      }  
      public void setAge(int age) {  
           this.age = age;  
      }  
 }  

Example 02

 package CollectionFramework;  
 import java.util.ArrayList;  
 import java.util.Collections;  
 import java.util.Comparator;  
 import java.util.List;  
 public class ComparatorExample {  
      public static void main(String[] args) {  
           String s1 = "Logitech";  
           String s2 = "Microsoft";  
           String s3 = "cooler Master";  
           String s4 = "Creative";  
           String s5 = "Zebronics";  
           String s6 = "iBall";  
           List<String> arrayList = new ArrayList<String>();  
           arrayList.add(s1);  
           arrayList.add(s2);  
           arrayList.add(s3);  
           arrayList.add(s4);  
           arrayList.add(s5);  
           arrayList.add(s6);  
           /*  
            * as long as all the names have same case the starting alphabet the  
            * sort method works Collections.sort(arrayList);  
            */  
           Collections.sort(arrayList, new Comparator<String>() {  
                @Override  
                public int compare(String s1, String s2) {  
                     return s1.compareToIgnoreCase(s2);  
                     // return 0;  
                }  
           });  
           for (int i = 0; i < arrayList.size(); i++) {  
                System.out.println(arrayList.get(i));  
           }  
      }  
 }