How to sort alphabetically while ignoring case sensitive?
JavaAndroidCollectionsJava Problem Overview
I have this code, but works only for lower case letters. I want this to sort the list while ignoring the upper case letters..
package sortarray.com;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
public class SortArray extends Activity {
ArrayList<String[]> matchedFruits = new ArrayList<String[]>();
TextView selection;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
String fruits[] = new String[7];// Sorted array
fruits[0] = "apple";
fruits[1] = "apricot";
fruits[2] = "banana";
fruits[3] = "mango";
fruits[4] = "melon";
fruits[5] = "pineapple";
fruits[6] = "peach";
char currChar = fruits[0].charAt(0);// Get first char of first element
boolean match = false;
int len = fruits.length;
List<String> tmp = new ArrayList<String>();
for (int i = 1; i < len; i++) {
Log.d("Comparing ", fruits[i].charAt(0) + "," + currChar);
if (fruits[i].charAt(0) == currChar) {
if (match == false)// new match?
{
match = true;// Reset search
tmp.clear();// clear existing items
tmp.add(fruits[i - 1]);
Log.d("Started new list ", fruits[i - 1]);
} else {
tmp.add(fruits[i - 1]);
Log.d("Added to list ", fruits[i - 1]);
}
} else {
match = false;
tmp.add(fruits[i - 1]);
matchedFruits.add(tmp.toArray(new String[tmp.size()]));// add to
// final
// list
Log.d("Finished a list ", fruits[i - 1]);
tmp.clear();// clear existing items
}
currChar = fruits[i].charAt(0);
}
tmp.add(fruits[len - 1]);
matchedFruits.add(tmp.toArray(new String[tmp.size()]));// add left over
// items
printList();
}
void printList()
{
//Print the list
TextView selection = (TextView) findViewById(R.id.tv);
String mssg="";
for(int i=0;i<matchedFruits.size();i++)
{
String tmp2[]= matchedFruits.get(i);
for (int j = 0; j < tmp2.length; j++) {
//Log.d("Final list", "Array #" + i + "[" + j + "]," + tmp2[j]);
mssg += tmp2[j].toString();
}
//selection.setText("\n");
selection.setText(mssg);
}
}
}
Java Solutions
Solution 1 - Java
Collections.sort(listToSort, String.CASE_INSENSITIVE_ORDER);
Solution 2 - Java
It is very unclear what you are trying to do, but you can sort a list like this:
List<String> fruits = new ArrayList<String>(7);
fruits.add("Pineapple");
fruits.add("apple");
fruits.add("apricot");
fruits.add("Banana");
fruits.add("mango");
fruits.add("melon");
fruits.add("peach");
System.out.println("Unsorted: " + fruits);
Collections.sort(fruits, new Comparator<String>() {
@Override
public int compare(String o1, String o2) {
return o1.compareToIgnoreCase(o2);
}
});
System.out.println("Sorted: " + fruits);
Solution 3 - Java
Collections.sort() lets you pass a custom comparator for ordering. For case insensitive ordering String class provides a static final comparator called CASE_INSENSITIVE_ORDER.
So in your case all that's needed is:
Collections.sort(caps, String.CASE_INSENSITIVE_ORDER);
Solution 4 - Java
Here's a plain java example of the best way to do it:
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
public class Sorter {
String fruits[] = new String[7];
List<String> lst;
Sorter() {
lst = new ArrayList<String>();
// initialise UNSORTED array
fruits[0] = "Melon"; fruits[1] = "apricot"; fruits[2] = "peach";
fruits[3] = "mango"; fruits[4] = "Apple"; fruits[5] = "pineapple";
fruits[6] = "banana";
}
public static void main(String[] args) {
Sorter srt = new Sorter();
srt.anyOldUnstaticMethod();
}
public void anyOldUnstaticMethod() {
Collections.addAll(lst, fruits);
System.out.println("Initial List");
for (String s : lst)
System.out.println(s);
Collections.sort(lst);
System.out.println("\nSorted List");
for (String s : lst)
System.out.println(s);
Collections.sort(lst, new SortIgnoreCase());
System.out.println("\nSorted Ignoring Case List");
for (String s : lst)
System.out.println(s);
}
public class SortIgnoreCase implements Comparator<Object> {
public int compare(Object o1, Object o2) {
String s1 = (String) o1;
String s2 = (String) o2;
return s1.toLowerCase().compareTo(s2.toLowerCase());
}
}
}
Solution 5 - Java
I can't believe no one made a reference to the Collator. Almost all of these answers will only work for the English language.
You should almost always use a Collator for dictionary based sorting.
For case insensitive collator searching for the English language you do the following:
Collator usCollator = Collator.getInstance(Locale.US);
usCollator.setStrength(Collator.PRIMARY);
Collections.sort(listToSort, usCollator);
Solution 6 - Java
I like the comparator class SortIgnoreCase, but would have used this
public class SortIgnoreCase implements Comparator<String> {
public int compare(String s1, String s2) {
return s1.compareToIgnoreCase(s2); // Cleaner :)
}
}
Solution 7 - Java
Since Java 8 you can sort using the Streams API:
List<String> fruits = Arrays.asList("apple", "Apricot", "banana");
List<String> sortedFruit = fruits.stream()
.sorted(String.CASE_INSENSITIVE_ORDER)
.collect(Collectors.toList())
The difference with Collections.sort is that this will return a new list and will not modify the existing one.
Solution 8 - Java
Pass java.text.Collator.getInstance() to Collections.sort method ; it will sort Alphabetically while ignoring case sensitive.
ArrayList<String> myArray = new ArrayList<String>();
myArray.add("zzz");
myArray.add("xxx");
myArray.add("Aaa");
myArray.add("bb");
myArray.add("BB");
Collections.sort(myArray,Collator.getInstance());
Solution 9 - Java
You can directly call the default sort method on the list like this:
myList.sort(String.CASE_INSENSITIVE_ORDER); // reads as the problem statement and cleaner
or:
myList.sort(String::compareToIgnoreCase); // reads as the problem statement and cleaner
Solution 10 - Java
Array Sorting in Java 8 Way-> Easy peasy lemon squeezy
String[] names = {"Alexis", "Tim", "Kyleen", "KRISTY"};
Arrays.sort(names, String::compareToIgnoreCase);
I used method Reference String::compareToIgnoreCase
Solution 11 - Java
In your comparator factory class, do something like this:
private static final Comparator<String> MYSTRING_COMPARATOR = new Comparator<String>() {
@Override
public int compare(String s1, String s2) {
return s1.compareToIgnoreCase(s2);
}
};
public static Comparator<String> getMyStringComparator() {
return MYSTRING_COMPARATOR;
This uses the compare to method which is case insensitive (why write your own). This way you can use Collections sort like this:
List<String> myArray = new ArrayList<String>();
//fill your array here
Collections.sort(MyArray, MyComparators. getMyStringComparator());
Solution 12 - Java
did you tried converting the first char of the string to lowercase on if(fruits[i].charAt(0) == currChar) and char currChar = fruits[0].charAt(0) statements?
Solution 13 - Java
Example using Collections and ArrayList:
Develop an intern static class like the example "CompareStrings".
Call the intern static class in the main method.
Easy to understand and works fine!
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
public class MainClass {
public static void main(String[] args) {
ArrayList<String> myArray = new ArrayList<String>();
myArray.add("zzz");
myArray.add("xxx");
myArray.add("Aaa");
myArray.add("bb");
myArray.add("BB");
Collections.sort(myArray, new MainClass.CompareStrings());
for(String s : myArray) {
System.out.println(s);
}
}
public static class CompareStrings implements Comparator<String> {
@Override
public int compare(String s1, String s2) {
return s1.compareToIgnoreCase(s2);
}
}
}
Solution 14 - Java
In your case you have a List of Strings and most of the already proposed solutions (I specially like @guyblank answer) are just fine but!!!, if you have a List of beans, which is my case, you can use Comparable interface in your bean like this:
public class UserBean implements Comparable<UserBean> {
private String name;
private String surname;
private Integer phone;
// GETTERS AND SETTERS
public int compareTo(UserBean bean) {
return name.compareToIgnoreCase(bean.name);
}
}
Then you only need to create your ArrayList<UserBean> userBeanArray = new ArrayList<UserBean>();, fill it and sort it: Collections.sort(userBeanArray);
And you have it done!
Hope to help to community ;-)
Solution 15 - Java
Here is an example to sort an array : Case-insensitive
import java.text.Collator;
import java.util.Arrays;
public class Main {
public static void main(String args[]) {
String[] myArray = new String[] { "A", "B", "b" };
Arrays.sort(myArray, Collator.getInstance());
System.out.println(Arrays.toString(myArray));
}
}
/* Output:[A, b, B] */