Doubling the size of an array: double the size of any type of array : Array Reflection Utilities « Collections « Java Tutorial

1. Java Tutorial
2. Collections
3. Array Reflection Utilities

import java.lang.reflect.Array;

public class MainClass {
  public static void main (String args[]) {
    int[] array = (int[])Array.newInstance(int.class, 3);

    for(int i=0;i<array.length;i++){
      array[i] = i;
      
    }    
    
    int[] arrayDoubled = (int[])doubleArray(array);

    for (int i: arrayDoubled) {
      System.out.println(i);
    }
  }
  static Object doubleArray(Object original) {
    Object returnValue = null;
    Class type = original.getClass();
    if (type.isArray()) {
      int length = Array.getLength(original);
      Class elementType = type.getComponentType();
      returnValue = Array.newInstance(elementType, length*2);
      System.arraycopy(original, 0, returnValue, 0, length);
    }
    return returnValue;
  }

}

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