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Dodajte elemente v Array v Javi

Niz je zbirka podobnih vrst elementov, shranjenih na sosednjih lokacijah v pomnilniku. Glavna prednost matrike je, da lahko do elementov matrike dostopamo naključno, medtem ko do elementov povezanega seznama ni mogoče naključno dostopati.

notri Java , Nizi so spremenljivi tipi podatkov, kar pomeni, da je velikost matrike fiksna in v matriko ne moremo neposredno dodati novega elementa. Vendar pa obstajajo različni načini za dodajanje elementov v matriko. Recimo, da imamo matriko arr in ji moramo dodati elemente. Za dodajanje elementov v arr.

  1. Z ustvarjanjem matrike večje velikosti kot arr.
  2. Z uporabo ArrayList
  3. S premikanjem elementa prilagodite velikost arr.

Oglejmo si načine, ki smo jih opisali, od znotraj.

Ustvarjanje matrike večje velikosti

Za dodajanje elementov v matriko java lahko ustvarimo drugo večjo matriko in kopiramo vse elemente iz naše matrike v drugo matriko ter postavimo novo vrednost na zadnji del na novo ustvarjene matrike. Vendar to ni učinkovit način za dodajanje elementa v matriko. V spodnjem primeru je element 7 dodan matriki arr s pomočjo na novo ustvarjene matrike newArr. Razmislite o naslednjem primeru.

 import java.util.Arrays; public class ArrayExample { public static void main(String[] args) { // TODO Auto-generated method stub int arr[] = {1,2,3,4,5,6}; int n = arr.length; int newArr[] = new int[n+1]; int value = 7; System.out.println(Arrays.toString(arr)); for(int i = 0; i<n; i++) { newarr[i]="arr[i];" } newarr[n]="value;" system.out.println(arrays.tostring(newarr)); < pre> <h3>Using ArrayList</h3> <p>We can use <a href="/java-arraylist">ArrayList</a> as the intermediate structure and add the elements into the ArrayList using the add () method. ArrayList is a data structure that allows us to dynamically add elements. However, we can convert the ArrayList to the array by using the toArray() method. Hence this process involves the following steps.</p> <ol class="points"> <li>Convert Array into ArrayList using asList() method.</li> <li>Add elements into the array list using the add() method.</li> <li>Convert the ArrayList again to the array using the toArray() method.</li> </ol> <p>Consider the following example.</p> <pre> import java.util.ArrayList; import java.util.Arrays; public class JavaAddElementUsingList { public static void main(String[] args) { // TODO Auto-generated method stub Integer arr[] = {1,2,3,4,5,6}; System.out.println(&apos;Array:&apos;+Arrays.toString(arr)); ArrayList arrayList = new ArrayList(Arrays.asList(arr)); arrayList.add(7); arr = arrayList.toArray(arr); System.out.println(&apos;Array after adding element: &apos;+Arrays.toString(arr)); } } </pre> <p> <strong>Output:</strong> </p> <pre> Array:[1, 2, 3, 4, 5, 6] Array after adding element: [1, 2, 3, 4, 5, 6, 7] </pre> <h3>Shifting elements to adjust the size of the array</h3> <p>In this method, we will add the elements to the specified index in the array. Likewise, the above two processes will use a new destination array with a larger size than the original array. However, it will be tricky to shift the destination array elements after copying all elements from the original array to destination array.</p> <p>In this method, we will,</p> <ol class="points"> <li>Create a new destination array with a larger size than the original array.</li> <li>Copy all the elements from the original array to the new destination array</li> <li>Shift the elements after the given index to the right until it reaches the end of the array.</li> <li>Insert the new element at the given index.</li> </ol> <p>Consider the following example in which we will add a specific value at the given index 3 in the original array using a destination array.</p> <pre> import java.util.Arrays; public class JavaAddElementArraySpecified { public static void main(String[] args) { Integer arr[] = {1,2,3,4,5,6}; int n = arr.length; int index = 3; System.out.println(&apos;Original Array: &apos;+Arrays.toString(arr)); Integer newArr[] = new Integer[n+1]; int j = 0; for(int i = 0; i<newarr.length; i++) { if(i="=index)" newarr[i]="7;" }else j++; } newarr[index]="7;" system.out.println('array after adding value: '+arrays.tostring(newarr)); < pre> <p> <strong>Output:</strong> </p> <pre> Original Array: [1, 2, 3, 4, 5, 6] Array after adding value: [1, 2, 3, 7, 4, 5, 6] </pre> <hr></newarr.length;></pre></n;>

Izhod: 

 Array:[1, 2, 3, 4, 5, 6] Array after adding element: [1, 2, 3, 4, 5, 6, 7]

Premikanje elementov za prilagajanje velikosti niza

Pri tej metodi bomo elemente dodali podanemu indeksu v matriki. Podobno bosta zgornja dva procesa uporabila novo ciljno matriko z večjo velikostjo od izvirne matrike. Vendar pa bo težko premakniti elemente ciljne matrike po kopiranju vseh elementov iz prvotne matrike v ciljno matriko.

Pri tej metodi bomo,

  1. Ustvarite novo ciljno matriko z večjo velikostjo od izvirne matrike.
  2. Kopirajte vse elemente iz prvotne matrike v novo ciljno matriko
  3. Premaknite elemente za danim indeksom v desno, dokler ne dosežejo konca matrike.
  4. Vstavite nov element na podani indeks.

Razmislite o naslednjem primeru, v katerem bomo dodali določeno vrednost pri danem indeksu 3 v izvirni matriki z uporabo ciljne matrike.

 import java.util.Arrays; public class JavaAddElementArraySpecified { public static void main(String[] args) { Integer arr[] = {1,2,3,4,5,6}; int n = arr.length; int index = 3; System.out.println(&apos;Original Array: &apos;+Arrays.toString(arr)); Integer newArr[] = new Integer[n+1]; int j = 0; for(int i = 0; i<newarr.length; i++) { if(i="=index)" newarr[i]="7;" }else j++; } newarr[index]="7;" system.out.println(\'array after adding value: \'+arrays.tostring(newarr)); < pre> <p> <strong>Output:</strong> </p> <pre> Original Array: [1, 2, 3, 4, 5, 6] Array after adding value: [1, 2, 3, 7, 4, 5, 6] </pre> <hr></newarr.length;>