Write a program to implement your own ArrayList class. It should contain add(), get(), remove(), size() methods. Use dynamic array logic. It should increase its size when it reaches threshold.
import java.util.Arrays; public class MyArrayList { private Object[] myStore; private int actSize = 0; public MyArrayList(){ myStore = new Object[10]; } public Object get(int index){ if(index < actSize){ return myStore[index]; } else { throw new ArrayIndexOutOfBoundsException(); } } public void add(Object obj){ if(myStore.length-actSize <= 5){ increaseListSize(); } myStore[actSize++] = obj; } public Object remove(int index){ if(index < actSize){ Object obj = myStore[index]; myStore[index] = null; int tmp = index; while(tmp < actSize){ myStore[tmp] = myStore[tmp+1]; myStore[tmp+1] = null; tmp++; } actSize--; return obj; } else { throw new ArrayIndexOutOfBoundsException(); } } public int size(){ return actSize; } private void increaseListSize(){ myStore = Arrays.copyOf(myStore, myStore.length*2); System.out.println("\nNew length: "+myStore.length); } public static void main(String a[]){ MyArrayList mal = new MyArrayList(); mal.add(new Integer(2)); mal.add(new Integer(5)); mal.add(new Integer(1)); mal.add(new Integer(23)); mal.add(new Integer(14)); for(int i=0;i<mal.size();i++){ System.out.print(mal.get(i)+" "); } mal.add(new Integer(29)); System.out.println("Element at Index 5:"+mal.get(5)); System.out.println("List size: "+mal.size()); System.out.println("Removing element at index 2: "+mal.remove(2)); for(int i=0;i<mal.size();i++){ System.out.print(mal.get(i)+" "); } } }
转载于:https://www.cnblogs.com/hygeia/p/5165050.html
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