import java.util.*;

public class TestArray {

private static int[] returnArray(int a, int b, int c) {

// Using {a, b, c} only won't work!

return new int[]{a, b, c};

}

// Using Enhanced For-Loops

private static void printArray(int[] array) {

System.out.print("Array content: ");

for (int i : array) {

System.out.print(i + " ");

}

System.out.println("");

}

public static void main (String[] args) {

int a1 = 3;

int a2 = 5;

int a3 = 7;

int[] arr = {a1, a2, a3};

System.out.println("Array length = " + arr.length);

printArray(arr);

int[] arr2 = returnArray(2, 4, 6);

printArray(arr2);

System.out.println("Second element = " + arr[1]);

int[] arr3 = new int[4];

printArray(arr3);

List<Integer> convertedList = Arrays.asList(4, 5, 6);

System.out.println("Converted List = " + convertedList);

Integer[] arr4 = {7, 8, 9}; //not int[]!

convertedList = Arrays.asList(arr4);

System.out.println("Converted List = " + convertedList);

//If the content of arr4 changes, so does that of the convertedList,

//because Arrays.asList returns a wrapper of original array, not a copy.

arr4[0] = -1;

System.out.println("Converted List = " + convertedList);

//Test 2d Array:

//http://stackoverflow.com/questions/12231453/syntax-for-creating-a-two-dimensional-array

int[][] nums = new int[][]{

{},

{1},

{1, 3, 5, 7},

{9, 8, 3, 11, -55},

{4, 4, 8, 12, 55, 3, 8, -3, 4}

};

for (int[] array : nums) {

System.out.println("Original array: " + Arrays.toString(array));

}

int[][] nums2 = new int[4][7];

for (int i = 0; i < nums2.length; ++i) {

for (int j = 0; j < nums2[i].length; ++j) {

System.out.print("(" + i + ", " + j + ")=" + nums2[i][j] + " ");

}

System.out.println("");

}

//Can the length of second dimension be 0? Yes!

int[][] nums3 = new int[4][0];

//int[][] nums3 = new int[0][0]; //First dimension can also have 0 length

System.out.println("nums3: 4 x 0: ");

for (int i = 0; i < nums3.length; ++i) {

System.out.print("Row " + i + ": ");

for (int j = 0; j < nums3[i].length; ++j) {

System.out.print("(" + i + ", " + j + ")=" + nums3[i][j] + " ");

}

System.out.println("");

}

//Array of super types

Animal[] animals = new Animal[3];

for (int i = 0; i < animals.length; ++i) {

animals[i] = new Cat(i, i*2, i+3);

}

for (Animal animal : animals) {

//Should output cat's info

System.out.println("Animal = " + animal);

}

//Cast array of T to array of T's super class

Cat[] cats = new Cat[3];

for (int i = 0; i < cats.length; ++i) {

cats[i] = new Cat(i, i*3, i+4);

}

Animal[] newAnimals = (Animal[])cats;

for (Animal newAnimal : newAnimals) {

//Should output cat's info too

System.out.println("New animal = " + newAnimal);

}

Object[] strings = new String[2];

strings[0] = "hi"; // OK

strings[1] = 100; // A run-time ArrayStoreException is thrown.

}

}