Term
What is the output?
static void a(int b)
{
b = 7;
}
public static void main()
{
int c = 5;
b(c);
System.out.println(c);
} |
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Definition
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Term
Which is preferred?
int[] x;
or
int x[]; |
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Definition
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Term
What is the output?
static void main()
{
int x[4] = new int[4];
x[3] = 1;
x[0] = 1;
x[2] = 7;
x[1] = 5;
for (int i=0; i<3; i++)
{
System.out.println(" " + x[i]);
}
} |
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Definition
| Does not compile. int x[4] is not legal. |
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Term
Which of the following will compile?
1) String random[][] = new String[9][]();
2) Integer [] ints = new Integer [] {7,8,9};
3) Integer [] ints2 = new Integer {7,8,9};
4) Integer [] ints3 = {7,8,9};
5) int [] bacon [] = new int [3][]{{4,7,2},{}};
6) int $[];
char[] $$;
$ = $$;
7) Car [] cars;
Nissan nissans[][];
cars = nissans;
8) New String[3] {“Dog”, null, “Bacon”}; |
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Definition
only 2,4
1 – illegal ();
3 – missing [];
5 – cannot declare size when creating anonymous array
6 – cannot assign char array to an int array
7 – type Nissan can be assigned to type car, but arrays must be of the same dimension.
8 – Not declare size when constructing anonymous array
Pg(231-234) |
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Term
In what order will the following happen?
When the first line of the static main method creates an instance of the Child class:
1) Parent’s Static Initialization blocks
2) Child’s Static Initialization blocks
3) Parent’s Initialization blocks
4) Childs Initialization blocks
5) Parent’s Constructor(s)
6) Child’s Constructors(s) |
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Definition
Answer:
1,2,3,5,4,6
Pg(234-237) |
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Term
In what order will the following happen?
*What special case will cause a different order?
Typically when the first line of the static main method creates an instance of the parent class:
1) Parent’s Static Initialization blocks
2) Child’s Static Initialization blocks
3) Parent’s Initialization blocks
4) Childs Initialization blocks
5) Parent’s Constructor(s)
6) Child’s Constructors(s) |
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Definition
Answer:
1,3,5,
*If the main method is imbedded in the child object then the order would be:
1,2,3,5
pg(234-237) |
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Term
| What are the two primary purposes of Java wrapper classes? |
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Definition
1) To provide a mechanism to wrap values in an object so that the values can be used for activities reserved for Objects such as the Collections API.
2) To provide an assortment of utility functions for primitives. |
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Term
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Definition
The part of memory where Java objects live, and the one and only part of memory that is in any way involved in the garbage collection process
(p. 255) |
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Term
| When does the garbage collector run? |
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Definition
The JVM decides when to run the garbage collector. One can request that it run through the code, but there are no guarantees that it will do so.
(p. 256) |
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Term
| When is an object eligible for garbage collection? |
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Definition
When no live thread can access it.
(p. 256) |
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Term
| What are the three ways one can remove a reference to an object, thereby making it eligible for garbage collection? |
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Definition
1. Set the reference to null.
2. Set the reference variable to refer to another object
3. Isolate a reference (make them an island, so that even if two objects reference one another, those objects themselves cannot be reached by any thread).
(p. 257-259) |
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Term
| What always runs just before an object is deleted by the garbage collector? |
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Definition
The finalize() method (inherited from Object)
(p. 263) |
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Term
| Can finalize() result in saving an object from deletion? |
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Definition
Yes - in that method, one could write code that passes a reference to the object in question back to another object, effectively uneligibilizing the object for garbage collection.
(p. 263) |
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Term
| T/F: The finalize() method can be called more than once |
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Definition
F: The finalize method is called only once (at most) by the garbage collector, and might never be called at all if the object is never eligible for deletion or the garbage collector never runs.
(p. 263) |
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Term
| Default value for Boolean variables is True. (T/F?) |
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Definition
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Term
| Float initializes to 0.0F. (T/F) |
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Definition
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Term
class ArrayExample {
public static void main(String[] args) {
int x = -1;
int y = 0;
int z = 1;
int[] myArray = new int[3]
myArray[y] = -1;
myArray[x] = 0;
myArray[z] = 1;
System.out.println(myArray[2][0]);
} }
What will the following output?
a. -1
b. 0
c. Compilation Error
d. Runtime Error
e. ArrayIndexOutOfBoundsException |
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Definition
| b. Runtime exception. x is a negative number. (pg 225) |
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Term
class ArrayExample {
public static void main(String[] args) {
int x = -1;
int[] tempArray = {{1,2,4,4}, {x,2}, {3,x}};
System.out.println(tempArray[1][0]);
}}
T/F - This will compile without errors. |
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Definition
| True - This will compile correctly, and output -1. (pg 226) |
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Term
How many objects are created on the heap with the following code?
int[][] tempArray = {{1,9,2,2}, {3,7}, {4,4}}; |
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Definition
| Four objects are created on the heap. (pg 228) |
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Term
class ArrayExample {
public static void main(String[] args) {
int x = 0;
int[] tempArray;
tempArray = new int[3] {4,x,2};
System.out.println(tempArray[2]);
}}
T/F - The following code will compile correctly and output 0. |
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Definition
| False - You cannot specify a size for an anonymous array creation syntax. (pg 230) |
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Term
What is the output of:
class AddBoxing {
static void go(Integer x) { System.out.println("Integer"); }
static void go(long x) { System.out.println("long"); }
public static void main(String[] args) {
int i=5;
go(i);
}
} |
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Definition
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Term
What is the output of:
class AddVarArgs {
static void go(int x, int y) { System.out.println("int,int"); }
static void go(byte... x) { System.out.println("byte..."); }
public static void main(String[] args) {
byte b=5;
go(b,b);
}
} |
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Definition
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Term
| Can you widen and then box? |
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Definition
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Term
| Can you box and then widen? |
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Definition
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Term
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Definition
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Term
What does the following Octal numbers equal in decimal:
A. int x = 011
B. int y = 010 |
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Definition
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Term
will this code compile?
byte b =3;
b = (byte) (b+7); |
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Definition
| Will not compile without the cast, since b + 7 results in an int. |
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