package org.kodejava.util;
import java.util.LinkedList;
import java.util.List;
public class LinkedListToArray {
public static void main(String[] args) {
List<String> list = new LinkedList<>();
list.add("Blue");
list.add("Green");
list.add("Purple");
list.add("Orange");
// Converting LinkedList to array can be done by calling the toArray()
// method of the List;
String[] colors = new String[list.size()];
list.toArray(colors);
for (String color : colors) {
System.out.println("color = " + color);
}
}
}
Tag Archives: Array
How do I sort array values in case-insensitive order?
By default, when sorting an arrays the value will be ordered in case-sensitive order. This example show you how to order it in case-insensitive order.
package org.kodejava.util;
import java.util.Arrays;
public class SortArrayCaseSensitivity {
public static void main(String[] args) {
String[] teams = new String[5];
teams[0] = "Manchester United";
teams[1] = "chelsea";
teams[2] = "Arsenal";
teams[3] = "liverpool";
teams[4] = "EVERTON";
// Sort array, by default it will be sorted in case-sensitive order.
// [Arsenal, EVERTON, Manchester United, chelsea, liverpool]
Arrays.sort(teams);
System.out.println("Case sensitive : " + Arrays.toString(teams));
// Sort array in case-insensitive order
// [Arsenal, chelsea, EVERTON, liverpool, Manchester United]
Arrays.sort(teams, String.CASE_INSENSITIVE_ORDER);
System.out.println("Case insensitive: " + Arrays.toString(teams));
}
}
The result of the code snippet above:
Case sensitive : [Arsenal, EVERTON, Manchester United, chelsea, liverpool]
Case insensitive: [Arsenal, chelsea, EVERTON, liverpool, Manchester United]
How do I remove duplicate element from array?
This example demonstrates you how to remove duplicate elements from an array using the help of java.util.HashSet class.
package org.kodejava.util;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
public class ArrayRemoveDuplicate {
public static void main(String[] args) {
// A string array with duplicate values.
String[] data = {"A", "C", "B", "D", "A", "B", "E", "D", "B", "C"};
System.out.println("Original array : " + Arrays.toString(data));
// Convert a string array into java.util.List because we need a list
// object to create the java.util.Set object.
List<String> list = Arrays.asList(data);
// A set is a collection object that cannot have a duplicate values,
// by converting the array to a set the duplicate value will be removed.
Set<String> set = new HashSet<>(list);
// Convert the java.util.Set back to array using the toArray() method of
// the set object copy the value in the set to the defined array.
String[] result = set.toArray(new String[0]);
System.out.println("Array with no duplicate: " + Arrays.toString(result));
}
}
The result of the code snippet above:
Original array : [A, C, B, D, A, B, E, D, B, C]
Array with no duplicate: [A, B, C, D, E]
How do I convert Array to java.util.Set?
package org.kodejava.util;
import java.util.*;
public class ArrayToSetExample {
public static void main(String[] args) {
Integer[] numbers = {7, 7, 8, 9, 10, 8, 8, 9, 6, 5, 4};
// To convert an array into a java.util.Set firstly we need to convert the
// array into a java.util.List using the Arrays.asList() method. With the
// List object created we can instantiate a new java.util.HashSet and pass
// the list as the constructor parameter.
List<Integer> numberList = Arrays.asList(numbers);
Set<Integer> numberSet = new HashSet<>(numberList);
// Or we can simply combine the line above into single line.
Set<Integer> anotherNumberSet = new HashSet<>(Arrays.asList(numbers));
// Display what we get in the set using iterator.
for (Iterator<Integer> iterator = numberSet.iterator(); iterator.hasNext(); ) {
Integer number = iterator.next();
System.out.print(number + ", ");
}
// Display what we get in the set using for-each.
for (Integer number : anotherNumberSet) {
System.out.print(number + ", ");
}
}
}
How do I convert varargs to an array?
Varargs can be seen as a simplification of array when we need to pass a multiple value as a method parameter. Varargs itself is an array that automatically created, for these reason you will be enabled to do things you can do with array to varargs.
In the example below you can see the messages parameter can be assigned to the String array variables, we can call the length method to the messages parameter as we do with the array. So actually you don’t need to convert varargs to array because varargs is array.
package org.kodejava.lang;
public class VarargsToArray {
public static void main(String[] args) {
printMessage("Hello ", "there", ", ", "how ", "are ", "you", "?");
}
public static void printMessage(String... messages) {
String[] copiedMessage = messages;
for (int i = 0; i < messages.length; i++) {
System.out.print(copiedMessage[i]);
}
}
}