Issue with Sort native method Java

sort list of objects in java without comparator
java sort list of objects by date property
how to sort arraylist in java without using sort method
java sort arraylist of objects
java sort arraylist of objects by field
how to sort arraylist of objects alphabetically in java
how to sort objects in java
collections.sort java

I'm trying to order elements using native sort method.

Code:

List<String> list = new ArrayList();
Collections.sort(list);

Input 1:

Before order: 65 31 37 37 72 76 61 35 57 37
After order:  31 35 37 37 37 57 61 65 72 76
Expected:     Ok.

Input 2:

Before order: 45 186 185 55 51 51 22 78 64 26 49 21
After order:  185 186 21 22 26 45 49 51 51 55 64 78
Expected:     21 22 26 45 49 51 51 55 64 78 185 186

The problem is that the method is sorting wrong in some cases, how can I solve it?

You have a List<String>, so Collections.sort is ordering the String(s) lexicographically. You could use a List<Integer> like

List<Integer> al = Arrays.asList(45, 186, 185, 55, 51, 51, 22, 78, 64, 26, 49, 21);
Collections.sort(al);
System.out.println(al);

But, if you must use String(s) then you'll need to provide a custom Comparator (because the default String ordering isn't what you want). Something like,

List<String> al = Arrays.asList("45", "186", "185", "55", "51", "51", //
        "22", "78", "64", "26", "49", "21");
Collections.sort(al, new Comparator<String>() {
    @Override
    public int compare(String o1, String o2) {
        return Integer.compare(Integer.parseInt(o1), Integer.parseInt(o2));
    }
});
System.out.println(al);

which outputs (like the first example)

[21, 22, 26, 45, 49, 51, 51, 55, 64, 78, 185, 186]

How To Sort Objects In Java, Let's look, how implementing Comparable or passing a Comparator solves the issue and sort method sorts the Collection. Sort using Comparable. It uses the very stable and iterative implementation of the array object of Merge Sort. Java provides a method to sort the array in reverse order too according to the requirement of the programmer to sort either in ascending or descending order. Collections.reverseOrder() method is used to sort the elements in reverse or descending order.

You should be using Integer comparator.

List<Integer> list = new ArrayList();
Collections.sort(list);

or

List<String> list = Arrays.asList(new String[]{"45", "186", "185", "55", "51", "51", "22", "78", "64", "26", "49", "21"});
Comparator<String> cmp = (String o1, String o2) -> Integer.valueOf(o1).compareTo(Integer.valueOf(o2));
Collections.sort(list,cmp);
System.out.println(list);

Different Approaches to Sorting Elements of an ArrayList in Java , This method will sort the elements (country names) of the ArrayList using natural ordering (alphabetically in ascending order). Lets's write some  sort() method is a java.util.Arrays class method. Syntax: public static void sort(int[] arr, int from_Index, int to_Index) arr - the array to be sorted from_Index - the index of the first element, inclusive, to be sorted to_Index - the index of the last element, exclusive, to be sorted This method doesn't return any value.

You should sort by

  1. integer value of string

That is

Collections.sort(list,
    Comparator.comparing(Integer::parseInt));

Or sort by

  1. length of string
  2. string itself

That is

Collections.sort(list,
    Comparator.comparing(String::length)
              .thenComparing(Function.identity()));

Sorting data in Java: how to sort a list of Strings or Integers, sort(myArray);. The above method takes an array of objects, but the Arrays class also provides similar methods for sorting primitive arrays. Next: other issues. What are Native methods in Java? Java applications can call code written in C, C++, or assembler. This is sometimes done for performance and sometimes to access the underlying host operating system or GUI API using the JNI. The steps for doing that are: 1. First write the Java code and compile it 2. Then create a C header file 3. Create C stubs file 4.

Problem with sorting on Italian string resources · Issue #26 , or admin #163. Closed. thewheat opened this issue on Nov 22, 2017 · 3 comments. Closed Conversation.validateListRequest(Conversation.java:145) at io.intercom.api. NativeMethodAccessorImpl.invoke0(Native Method) at sun.​reflect. Cannot resolve corresponding JNI function Java_ai_kitt_snowboy_snowboyJNI_SnowboyDetect_1RunDetection_1_1SWIG_10 Reports native method declarations in Java where no corresponding JNI function is fo

Listing conversation with only order/sort fails unless specifying a , Java merge sort is a type of sorting method in which the array is algorithm in which we first divide the problem into many subproblems. Trying to use either keyboard() or mouse() on an element results in the following stacktrace: java.lang.IllegalArgumentException: object is not an instance of declaring class at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

Merge Sort in Java Example, The sort() method sorts the elements of an array in place and returns the sorted array. The default sort order is ascending, built upon converting  The native keyword is applied to a method to indicates that the method is implemented in native code using JNI (Java Native Interface). native is a modifier applicable only for methods and we can’t apply it anywhere else. The methods which are implemented in C, C++ are called as native methods or foreign methods.

Comments
  • use a Comparator
  • Can you tell us your expected result and the actual result ?
  • @Iyen, ok, done.
  • It's probably worth pointing out that in Java 8 you can do it particularly succinctly: list.sort(Comparator.comparingInt(Integer::parseInt));
  • Thanks. And, yes I have to use it as String. Nice contribution @PaulBoddington. By the way, when I wrote that code of @ElliottFricsh, Netbeans shows me another option to use lambda: (String o1, String o2) -> Integer.compare(Integer.parseInt(o1), Integer.parseInt(o2)));. Just to contribute also.