Library

Arrays Unit Test

By Mickey Arnold
Last updated 10 months ago
20 Questions

Consider the following method below.
public static double check(int[] vals)
{
double[] amounts = {.15,.2,.5,.01};
if(amounts.length != vals.length){
return 0.0;
}
double total = 0.0;
for(int i = 0; i < vals.length; i++)
{
total += vals[i] * amounts[i];
}
return total;
}
What will the method check() return if passed the array {7, 3, 5, 4}?

Consider the following method below.
public static double check(int[] vals)
{
double[] amounts = {.15,.2,.5,.01};
if(amounts.length != vals.length){
return 0.0;
}
double total = 0.0;
for(int i = 0; i < vals.length; i++)
{
total += vals[i] * amounts[i];
}
return total;
}
What will the method check() return if passed the array {7, 5, 4}?

Which of the following swaps elements 0 and 1 in array?
int[] array = {7,8,10,11,4,3};

I.
array[0] = array[1];
array[1] = array[0];

II.
int save = array[0];
array[0] = array[1];
array[1] = save;

III.
array[0]+= array[1];
array[1] = array[0]+array[1];
array[0]-= array[1];

What is output by the code below?
int[] array = {33,14,37,11,27};
System.out.println( array[ 6 - 3 ] );

What is output by the code below?
int[] array = {7,8,10,11,4,3};
Arrays.sort( array );
System.out.println(array[2]);

What is output by the code below?
int[] nums = new int[10];
for (int i=0; i<nums.length; i++)
{
nums[i] = i*3;
}
System.out.println(nums[6]);

What is output by the code below?
int[] array = {7,8,10,11,4,3};
array[array[0]/2]=15;
array[array[4]-4]=9;
array[array.length/2-1]=5;
array[1]=array[0]+4;
System.out.println(array[0]);

Which of the following correctly fill /* blank */ in method isIt() ?
//method isIt should return true if all of the numbers
//in array are in increasing ( ascending ) order
public static boolean isIt(int[] array)
{
for(int spot=0; spot<array.length-1; spot++)
{
/* blank */
return false;
}
return true;
}

What is output by the following code?
int[] array = {1,2,3,4,0};
int aplus = array[array[array[array[0]]]];
System.out.println( aplus );

Consider the following instance variable and incomplete method.
The method getBiggest should return the largest value in tRay.

private int[] tRay; //assume the tRay contains values
public int getBiggest()
{
int big = Integer.MIN_VALUE;

/* blank */

return big;
}

Which of the following code segments shown below could be used to replace
/* blank */ so that getBiggest will work as intended?

I. for( int i=0; i<tRay.length; i++ )
if( tRay[i] > big )
big = tRay[i];

II. for( int item : tRay )
if( tRay[item] > big )
big = tRay[item];

III. for( int item : tRay )
if( item > big )
big = item;

What is output by the code below?
int[] array = {7,8,10,11,4,3};
array[array[0]/2]=15;
array[array[4]+1]=9;
array[array.length/2-1]=5;
array[1]=array[0]+4;
out.println(array[5]);

What is output by the code below?
String s = "apluscompsci.com";
String words[] = new String[ s.length() ];
for (int b = s.length()-1; b>=0 ;b--)
words[b] = s.substring(b);
Arrays.sort(words);
System.out.println(words[2].length());

What is output by the code below?
String[] ray = "10 22 5 33 11 4 222".split(" ");
Arrays.sort( ray );
int x = Integer.parseInt( ray[0] );
int r = Integer.parseInt( ray[1] );
x += r;
System.out.println( x );

What is output by the code below?

Integer[] ray;
ray = new Integer[4];
System.out.println( ray[3] );

Consider the following class definitions below to determine the output of the provided code segments.
public class Cat
{
private String name;
private int age;
public Cat( String n, int a )
//implementation not shown
public String getName()
//implementation not shown
public int getAge()
//implementation not shown

//other methods not shown
}
//client code in another class
Cat[] bunch = new Cat[5];
bunch[4] = new Cat("wile", 5);
System.out.println( bunch[4].getAge() );

What is output by the code below?

String[] ray;
ray = new String[5];
ray[1] = "one";
ray[2] = "two";
ray[3] = "three";
ray[0] = ray[2];
ray[2] = null;
System.out.println( ray[4].length() );

Consider the following class definitions.
public class Cat
{
private String name;
private int age;

public String getName()
//implementation not shown
public int getAge()
//implementation not shown

//constructors and other methods not shown
}
public class CatBarn
{
private Cat[] kitties; //assume kitties has stuff in it

//returns the average age of all of the kitties
public double averageAge( ){
/* blank */
}
//constructors and other methods not shown
}
Which of the following code segments shown below could be used to replace
/* blank */ so that method averageAge() will work as intended?
I.
int cnt = 0;
double sum = 0;
for( Cat c : kitties )
{
sum += c.getAge();
cnt = cnt + 1;
}
return sum / cnt;

II.
int cnt = 0;
double sum = 0;
for( Cat c : kitties )
{
sum = sum + c;
cnt += 1;
}
return sum / cnt;

III.
double sum = 0;
for( int i = 0; i < kitties.length; i++ )
sum += kitties[i].getAge();
return sum / kitties.length;

Consider the following instance variable and incomplete method.
The method getBiggies should return a new ArrayList
that contains all values in list that are larger than val.

private List<Double> list; //assume list contains values

public List<Double> getBiggies( double val)
{
ArrayList<Double> bigs = new ArrayList<Double>();

/* blank */

return bigs;
}

Which of the following code segments shown below could be used to replace
/* blank */ so that getBiggies will work as intended?

I. for ( int i = 0; i < list.size(); i++)
if( list.get(i) > val )
bigs.add(i);
II. for ( int i = 0; i < list.size(); i++)
if( list.get(i) > val )
bigs.add(val);
III. for ( int i = 0; i < list.size(); i++)
if( list.get(i) > val )
bigs.add(list.get(i));
IV. for ( double item : list )
if( item > val )
bigs.add(item);

What is output by the code below?
Double[] ray = {3.1,5.2,6.3,1.4};
for( double r : ray )
r = 0;
System.out.println( ray[2] );

Consider the code below.

<blank>[] ray = {12,55,-988,9.6,0};
for( <blank> dog : ray )
System.out.println( dog );
Which of the following could fill <blank> ?