- Can the following be declared with arrays in Java?
int [][] globalArray = new int [3][];
Answer:
Yes. As a counter example the following line of code is incorrect and will result in a compiler error.
int [][] array1 = new int[][];
A minimum of 1 dimension is required when declaring arrays in Java.
- Write a Java constructor that accepts 2 array arguments.
Answer:
public class ArrayDemo {
private int[] num1 = new int[3];
private int[] num2 = new int[3];
public ArrayDemo() { };
public ArrayDemo(int[] array1, int[] array2) {
this.num1 = array1;
this.num2 = array2;
}
public static void main(String[] args) {
ArrayDemo ad1 = new ArrayDemo(new int[] {1,2,3} ,new int[] {1,2,3} );
}
}
- Can a constructor take a) arrays b) objects as parameters?
Answer:
Yes
- What are arguments when calling a method?
Answer:
Arguments are the elements you specify between the parentheses when you are invoking a method. The parameters are the elements in the methods signature.
- What is static import?
Answer:
static import enables access to static members of a class without need to qualify it by the class name.
- How can you think of each of the elements in the primeArray?
int [][] primeArray = {{1,3,5}, { 7,11,13}, { 17, 19, 23}};
Answer:
Each of the 3 elements in the primeArray is a reference variable to an int array.
- How do you create an anonymous array in Java.
Answer:
class AnonymousArray{
static void print(int a[]) {
for(int i=0;i<a.length;++i)
System.out.print(a[i]+" ");
}
static void print(int a[][]) {
for(int i=0;i<a.length;++i){
for(int j=0;j<a[i].length;++j)
System.out.print(a[i][j]+" ");
System.out.println("");
}
}
public static void main(String...s){
//1d anonymous array
print(new int[]{11,23,31,43});
System.out.println("\n Anonymous Array");
//2d anonymous array
print(new int[][]{{2,3},{5,7},{11,13}});
}
}
- How can you create an anonymous array for an array of int?
Answer:
int[] testScores;
testScores = new int[] {4,7,2};
- Which primitive datatypes can an array of int hold?
Answer:
a) byte b) char c) short.
-
What types of data can be assigned to an array?
Answer:
Any object that passes the "IS-A" test for the declared array type can be assigned to an element of that array.