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Array Reallocation

You can make a clone of an array and make the new array have a different size. public static boolean[] copyOf (boolean[] original, int newLength) public static byte[] copyOf (byte[] original, int newLength) public static char[] copyOf (char[] original, int newLength) public static double[] copyOf (double[] original, int newLength) public static float [] copyOf (float[] original, int newLength) public static int[] copyOf (int[] original, int newLength) public static long[] copyOf (long[] original, int newLength) public static short[] copyOf (short[] original, int newLength) public static <T> T[] copyOf (T[] original, int newLength) public static <T,U> T[] copyOf (U[] original, int newLength,java.lang.Class<? extends T[]> newType) The last method allows you to upcast each element in the original array to a parent type. Another method similar to copyOf that is also added to Arrays in Java 6 is copyOfRange. copyOfRange copies a range of elements to a new array. Like copyOf, copyOfRange also provides overrides for each Java data type. Here are their signatures: public static boolean[] copyOfRange (boolean[] original,int from, int to) public static byte[] copyOfRange (byte[] original,int from, int to) public static char[] copyOfRange (char[] original,int from, int to) public static double[] copyOfRange (double[] original,int from, int to) public static float[] copyOfRange (float[] original,int from, int to) public static int[] copyOfRange (int[] original, int from, int to) public static long[] copyOfRange (long[] original, int from, int to) public static short[] copyOfRange (short[] original, int from, int to) public static <T> T[] copyOfRange (T[] original, int from, int to) public static <T,U> T[] copyOfRange (U[] original, int from,int to, java.lang.Class<? extends T[]> newType) Array reallocation example import java.util.Arrays; public class ArrayReallocationDemo {   public static void main(String[] args) {     int[] data1 = new int[] { 1, 3, 5, 7, 9 };     printArray(data1);     int[] data2 = Arrays.copyOf(data1, 6);     data2[5] = 11;     printArray(data2);     int[] data3 = Arrays.copyOfRange(data1, 2, 10);     printArray(data3);   }   // print array elements   private static void printArray(int[] data) {     StringBuilder stringBuilder = new StringBuilder("[");     for (int i = 0; i < data.length; i++) {       stringBuilder.append(data[i]);       if (i < data.length - 1)         stringBuilder.append(", ");     }     stringBuilder.append("]");     System.out.println(stringBuilder);   } } [1, 3, 5, 7, 9] [1, 3, 5, 7, 9, 11] [5, 7, 9, 0, 0, 0, 0, 0]