U Javi, niz rezanje na kriške je način da dobijete podniz danog niza. Pretpostavimo da je a[] niz. Ima 8 elemenata indeksiranih od a[0] do a[7].
a[] = {8, 9, 4, 6, 0, 11, 45, 21}
logika prvog reda
Sada želimo pronaći dio indeksa polja od a[3] do a[6]. Gdje je a[3] početni indeks, a [6] krajnji indeks. Stoga dobivamo sljedeće narezan niz :
a[] = {6, 0, 11, 45}
U ovom odjeljku naučit ćemo kako pronaći isječak niza u Javi.
Postoje sljedeća tri načina za pronalaženje isječka niza:
- Kopiranjem elemenata
- Korištenjem metode copyOfRange().
- Korištenje Java 8 Stream
Razmotrimo svaku metodu detaljno.
modifikatorske tipke
Kopiranjem elemenata
To je izvorna metoda za dobivanje isječka niza. U ovoj metodi prvo pronalazimo početni i završni indeks zadanog niza. Nakon toga kreiramo prazan niz (sliced array) veličine (endIndex - startIndex). Iz zadanog niza kopirajte elemente (iz startIndexa) u isječeni niz. Na kraju ispišite izrezani niz.
Implementirajmo gornji pristup u a Java program za dobivanje isječenog niza zadanog niza. U ovom programu. koristit ćemo niz primitivnih tipova.
SliceArrayExample1.java
import java.util.Arrays; public class SliceArrayExample1 { //creating a functiion to the slice of an array public static int[] getSlice(int[] array, int startIndex, int endIndex) { // Get the slice of the Array int[] slicedArray = new int[endIndex - startIndex]; //copying array elements from the original array to the newly created sliced array for (int i = 0; i <slicedarray.length; i++) { slicedarray[i]="array[startIndex" + i]; } returns the slice of an array return slicedarray; main() method public static void main(string args[]) from which we will find int[] 56, 78, 22, 45, 90, 67, 91, 0, 31}; start index and end denotes part original to be int startindex="3," endindex="8;" get slicedarray="getSlice(array," startindex, 1); prints system.out.println('slice array: '+arrays.tostring(slicedarray)); < pre> <p> <strong>Output:</strong> </p> <pre> Slice of Array: [22, 45, 90, 67, 91, 0] </pre> <h2>By Using the copyOfRange() Method</h2> <p>The copyOfRange() method belongs to the Java Arrays class . It copies the specified range of the array to the newly created array (slice array) and returns the newly created array that contains the specified range from the original array. It takes <strong>O(n)</strong> time to create slicing of an array and <strong>O(n)</strong> space to store elements, where n is the number of elements of the resulting array.</p> <p> <strong>Syntax:</strong> </p> <pre> public static int[] copyOfRange(int[] original, int from, int to) </pre> <p>The method parses the three parameters:</p> <ul> <tr><td>original:</td> It is an array whose slice is to find. </tr><tr><td>from:</td> It is the start index. It must lie between 0 to the length of the given array. </tr><tr><td>to:</td> It is the end index. </tr></ul> <p>It throws the following exceptions:</p> <ul> <tr><td>ArrayIndexOutOfBoundsException:</td> If from is less than 0 or from is greater than the length of the specified array. </tr><tr><td>IllegalArgumentException:</td> If the parameter from is greater than to. </tr><tr><td>NullPointerException:</td> If the given array is null. </tr></ul> <p> <strong>SliceArrayExample2.java</strong> </p> <pre> import java.util.Arrays; public class SliceArrayExample2 { //function to get slice of a primitive array in Java public static int[] slice(int[] array, int startIndex, int endIndex) { // Get the slice of the Array int[] slicedArray = Arrays.copyOfRange(array, startIndex, endIndex); // return the slice return slicedArray; } public static void main(String args[]) { //get the array, startIndex and endIndex int[] array = {11, 23, 56, 90, 111, 901, 251, 800, 843}; int startIndex = 2, endIndex = 6; //get the slice of the array int[] sliceArray = slice(array, startIndex, endIndex + 1); //prints the slice of an array System.out.println('Slice of Array: '+Arrays.toString(sliceArray)); } } </pre> <p> <strong>Output:</strong> </p> <pre> Slice of Array: [56, 90, 111, 901, 251] </pre> <h2>By Using Java 8 Stream</h2> <p>By using the following steps, we can find the slice of an array using the Java 8 Stream.</p> <ul> <li>First, find the startIndex and endIndex array.</li> <li>Convert the elements (that are in range) into Primitive Stream using range() method.</li> <li>Using the <strong>map()</strong> method map the specified elements from the specified array.</li> <li>By invoking the <strong>toArray()</strong> method, convert the mapped array into an array.</li> <li>Print the <strong>sliced</strong> </li> </ul> <p> <strong>SliceArrayExample3.java</strong> </p> <pre> import java.util.Arrays; import java.util.stream.IntStream; public class SliceArrayExample3 { //user defined function that finds the sslice of an specified array public static int[] findSlice(int[] array, int startIndex, int endIndex) { //getting the slice of an array and storing it in array slcarray[] //the range() method converts the elements into stream //getting the elments of the int stream using lambda expression //converting the mapped elements into sliced array using the toArray() method int[] slcarray = IntStream.range(startIndex, endIndex).map(i -> array[i]).toArray(); //returns the slice of array return slcarray; } //main() method public static void main(String args[]) { //Get the array, startIndex and endIndex int[] array = {12, 45, 90, 55, 34, 100, 345, 897, 67, 123, 0, 789}; int startIndex = 5, endIndex = 10; //Get the slice of the array int[] slcarray = findSlice(array, startIndex, endIndex + 1); //Print the slice of the array System.out.println('Slice of array for the specified range is: '+Arrays.toString(slcarray)); } } </pre> <p> <strong>Output:</strong> </p> <pre> Slice of array for the specified range is: [100, 345, 897, 67, 123, 0] </pre> <hr></slicedarray.length;> Korištenjem metode copyOfRange().
Metoda copyOfRange() pripada klasi Java Arrays. Kopira navedeni raspon niza u novostvoreni niz (niz isječaka) i vraća novostvoreni niz koji sadrži navedeni raspon iz izvornog niza. Treba Na) vrijeme za stvaranje rezanja niza i Na) prostor za pohranu elemenata, gdje je n broj elemenata rezultirajućeg niza.
bash nizovi
Sintaksa:
public static int[] copyOfRange(int[] original, int from, int to)
Metoda analizira tri parametra:
Dopušta sljedeće iznimke:
SliceArrayExample2.java
mojlivecriklet
import java.util.Arrays; public class SliceArrayExample2 { //function to get slice of a primitive array in Java public static int[] slice(int[] array, int startIndex, int endIndex) { // Get the slice of the Array int[] slicedArray = Arrays.copyOfRange(array, startIndex, endIndex); // return the slice return slicedArray; } public static void main(String args[]) { //get the array, startIndex and endIndex int[] array = {11, 23, 56, 90, 111, 901, 251, 800, 843}; int startIndex = 2, endIndex = 6; //get the slice of the array int[] sliceArray = slice(array, startIndex, endIndex + 1); //prints the slice of an array System.out.println('Slice of Array: '+Arrays.toString(sliceArray)); } } Izlaz:
Slice of Array: [56, 90, 111, 901, 251]
Korištenjem Java 8 Stream-a
Koristeći sljedeće korake, možemo pronaći isječak niza koristeći Java 8 Stream.
- Prvo pronađite polje startIndex i endIndex.
- Pretvorite elemente (koji su u rasponu) u primitivni tok pomoću metode range().
- Koristiti karta() metoda preslikava navedene elemente iz navedenog niza.
- Pozivanjem na toArray() metodom, pretvorite mapirani niz u niz.
- Ispiši narezan na kriške
SliceArrayExample3.java
import java.util.Arrays; import java.util.stream.IntStream; public class SliceArrayExample3 { //user defined function that finds the sslice of an specified array public static int[] findSlice(int[] array, int startIndex, int endIndex) { //getting the slice of an array and storing it in array slcarray[] //the range() method converts the elements into stream //getting the elments of the int stream using lambda expression //converting the mapped elements into sliced array using the toArray() method int[] slcarray = IntStream.range(startIndex, endIndex).map(i -> array[i]).toArray(); //returns the slice of array return slcarray; } //main() method public static void main(String args[]) { //Get the array, startIndex and endIndex int[] array = {12, 45, 90, 55, 34, 100, 345, 897, 67, 123, 0, 789}; int startIndex = 5, endIndex = 10; //Get the slice of the array int[] slcarray = findSlice(array, startIndex, endIndex + 1); //Print the slice of the array System.out.println('Slice of array for the specified range is: '+Arrays.toString(slcarray)); } } Izlaz:
Slice of array for the specified range is: [100, 345, 897, 67, 123, 0]