Java Program:
Write a program to implement ArrayList.
Description:
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.
Code:
package com.java2novice.algos;
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)+" ");
}
}
}
Output:
2 5 1 23 14
New length: 20
Element at Index 5:29
List size: 6
Removing element at index 2: 1
2 5 23 14 29
Write a program to implement ArrayList.
Description:
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.
Code:
package com.java2novice.algos;
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)+" ");
}
}
}
Output:
2 5 1 23 14
New length: 20
Element at Index 5:29
List size: 6
Removing element at index 2: 1
2 5 23 14 29
Post a Comment