[ Published on -
1. Java - Primitives
2. Java - Strings
3. Java - Arrays
4. Java - Date
5. Java - Generics
6. Java - Collections
7. Java - Localization
8. Java - Formatting
9. Java - Regular Expressions
10. Java - System
11. Java - Serialization
12. Java - Multithreading
13. Java - IO/File
14. Java - Networking
15. Java - ORM - JPA
a) Simple User entity class
package basics.basicsExamples;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import basics.collectionsExamples.comparators.IntegerComparator;
/** ****************************************************************************
* ARRAY EXAMPLE CLASS
* @author stanislav.zorjan
*/
public class ArrayExample {
private byte [] byteArray0 = {1, 2, 4, 5};
private byte [] byteArray1 = new byte[10];
private byte [] byteArray2 = "This is a string".getBytes();
private Byte [] byteArray3 = new Byte[]{1,2,3,4,5};
private Byte [][] byteArray4 = new Byte[][]{{1,3,4},{1,2,3}};
private short [] shortArray0 = {1,2,3,4,5};
private short [] shortArray1 = new short[10];
private Short [] shortArray2 = new Short[]{1,2,3,4,5};
private int [] intArray0 = {1,2,3,4,5};
private int [] intArray1 = new int[10];
private Integer [] intArray2 = new Integer[]{1,2,3,4,5};
private Integer [] intArray3 = new Integer[]{2,2,3,4,5};
private long [] longArray0 = {1, 2L, 3l, 3000000000L, 5000000000L};
private long [] longArray1 = new long[10];
private Long [] longArray2 = new Long[]{1L, 2L, 3l, 3000000000L, 5000000000L};
private float [] floatArray0 = {1, 123, 12.12F, 123421.3F};
private float [] floatArray1 = new float[10];
private Float [] floatArray2 = new Float[]{1F, 123F, 12.12F, 123421.3F};
private double [] doubleArray0 = {1, 123D, 1123.12D, 12312.123};
private double [] doubleArray1 = new double[10];
private Double [] doubleArray2 = new Double[]{1D, 123D, 1123.12D, 12312.123};
private boolean [] booleanArray0 = {true, false, true, true, false};
private boolean [] booleanArray1 = new boolean[10];
private Boolean [] booleanArray2 = new Boolean[]{true, false, true, true, false};
private char [] charArray0 = {'c', 'd', '3', '\u00AE'};
private char [] charArray1 = new char[10];
private Character [] charArray2 = new Character[]{'c', 'd', '3', '\u00AE'};
private String [] str0 = {"0", "1", "2", "3"};
private String [] str1 = new String[10];
private String [] str2 = new String[]{"1", "2", "3", "4"};
/** ************************************************************************
* Default constructor
*/
public ArrayExample() {
//printArrays();
arrayOperations();
}
/** ************************************************************************
* Printing arrays
*/
private void printArrays(){
System.out.println("");
System.out.println("byte array");
System.out.println(Arrays.toString(this.byteArray0));
System.out.println(Arrays.toString(this.byteArray1));
System.out.println(Arrays.toString(this.byteArray2));
System.out.println("");
System.out.println("short array");
System.out.println(Arrays.toString(this.shortArray0));
System.out.println(Arrays.toString(this.shortArray1));
System.out.println("");
System.out.println("int array");
System.out.println(Arrays.toString(this.intArray0));
System.out.println(Arrays.toString(this.intArray1));
System.out.println("");
System.out.println("long array");
System.out.println(Arrays.toString(this.longArray0));
System.out.println(Arrays.toString(this.longArray1));
System.out.println("");
System.out.println("float array");
System.out.println(Arrays.toString(this.floatArray0));
System.out.println(Arrays.toString(this.floatArray1));
System.out.println("");
System.out.println("double array");
System.out.println(Arrays.toString(this.doubleArray0));
System.out.println(Arrays.toString(this.doubleArray1));
System.out.println("");
System.out.println("boolean array");
System.out.println(Arrays.toString(this.booleanArray0));
System.out.println(Arrays.toString(this.booleanArray1));
System.out.println("");
System.out.println("char array");
System.out.println(Arrays.toString(this.charArray0));
System.out.println(Arrays.toString(this.charArray1));
}
/** ************************************************************************
* Array operations method
*/
private void arrayOperations(){
// converting array to List
// For List interface see "collections.CollectionsExample" class
// if you need to convert array to list by using Arrays.toList method,
// than create "wrapped/boxed" array (Integer, Character, Float...),
// otherwise if used primitive type, array values won't be copied to list
// but instead, the whole array without conversion to list will
// become the list element.
List list = Arrays.asList(this.byteArray3);
System.out.println(list);
// searching array using binarySearch algorithm
System.out.println(Arrays.binarySearch(intArray2, 4));
/* searching range of array using binarySearch algorithm
* if fromIndex is > than searched object, result will
* be number less than 0
*
* For example: Integer [] intArray = new int[]{1,2,3,4,5};
* Arrays.binarySearch(intArray, 3, 4, 3);
* will return -4 or -(fromIndex+1)
*/
/*
* @param arrayToSearch
* @param fromIndex
* @param toIndex
* @searchedValue
*/
System.out.println(Arrays.binarySearch(intArray2, 0, 4, 2));
// creating new array by copying array
System.out.println(Arrays.toString(Arrays.copyOf(intArray0, 2)));
// creating new array by copying only a particular range of array
System.out.println(Arrays.toString(Arrays.copyOfRange(intArray0, 2, 4)));
// compares two non primitive arrays (Integer, Double, Character...)
System.out.println(Arrays.equals(intArray2, intArray3));
System.out.println(Arrays.deepEquals(intArray2, intArray3));
// Arrays hash code
System.out.println(Arrays.deepHashCode(intArray2));
// prints array with all nested arrays
System.out.println(Arrays.deepToString(this.byteArray4));
// fills all array positions with value
Arrays.fill(intArray2, 10);
System.out.println(Arrays.toString(intArray2));
// fills array positions within specified range
Arrays.fill(intArray2, 1, 4, 4);
System.out.println(Arrays.toString(intArray2));
// sorting in natural ascending order
Arrays.sort(intArray2);
System.out.println(Arrays.toString(intArray2));
// sorting array using comparator
Arrays.sort(intArray2, new IntegerComparator());
System.out.println(Arrays.toString(intArray2));
// sorting only specified range of the array using comparator
Arrays.sort(intArray2, 2, 4, new IntegerComparator());
System.out.println(Arrays.toString(intArray2));
// shuffling array
Collections.shuffle(Arrays.asList(intArray2));
System.out.println(Arrays.asList(intArray2));
System.out.println(Arrays.toString(intArray2));
}
}