Array error practice

by Tim Bahls

public class Del {

            public static void main

(String[] args){

                        //CODE HERE

            }         

}

Suppose the code below replaced "//CODE HERE".  What code would compile?  What would throw an Exception?  What would the code do?  What am I trying to teach you in each case? The ones that are marked by * are not very fair questions--the do not cover course material.

1.

arr[0]=3;

System.out.println(arr[0]);

2.

int[] arr;

arr[0]=3;

System.out.println(arr[0]);

3.

int[] arr=new int[3];

arr[0]=3;

System.out.println(arr[0]);

4.

int[] arr=new int[3];

System.out.println(arr[0]+arr[1]);

5.

int[] arr=new int[3];

Array error practice

public class Del {

            public static void main

(String[] args){

                        //CODE HERE

            }         

}

Suppose the code below replaced "//CODE HERE".  What code would compile?  What would throw an Exception?  What would the code do?  What am I trying to teach you in each case? The ones that are marked by * are not very fair questions--the do not cover course material.

1.

arr[0]=3;

System.out.println(arr[0]);

2.

int[] arr;

arr[0]=3;

System.out.println(arr[0]);

3.

int[] arr=new int[3];

arr[0]=3;

System.out.println(arr[0]);

4.

int[] arr=new int[3];

System.out.println(arr[0]+arr[1]);

5.

int[] arr=new int[3];

System.out.println(arr[-1]);

6.

int[] arr=new int[3];

System.out.println(arr[1.5]);

7.

int[] arr=new int[3];

System.out.println(arr[1.0]);

8.

int[] arr=new int[3];

arr[1]=6.0;

9.

double[] arr=new int[3];

10.

int[] arr;

arr = new int[3];

11.

int[] arr = new int[0];

12.

boolean[][] arr;

13.

int[] arr = new int[7];

System.out.println(arr[7]);

14.

int[] arr = new int[7];

System.out.println(arr.length());

15.

int[] arr = new int[7];

System.out.println(arr.equals(arr));

16.

float[] arr = new float[3];

arr[2] = 123L;

17.

long[] arr = new long[2];

arr[2] = 34f;

18.

int[] arr = new int[2]

System.out.println("hello"+arr );

19*

int x = (new int[2])[0];

20*

(new int[2])[0]=3;

21.

int[] a = new int[];

22.

int[] short = new int[10];

int[] medium = new int[100];

int[] long = new int[10000];

23.

int[] a = new int[1000000000];

24.

int[] a = new int[10000000000];

25.

int[] a = new int[100L];

26.

int[] a = new int[5];

for(int i = 0; i <= 5; i++){

            System.out.println(a[i]);

}

27.

int[] a = new int[5];

System.out.println(a.length == 4);

28.

int[] a = new int[5];

a.length = 7;

29.

int[] a = new int[5];

if(a.length = 5)

            System.out.println("Y");

30.

int[] a = new int[3];

int i=0;

while i < 3 {

            a[i] = i;

}

31.

int[] a = new int[3];

int i=0;

while(i < 3)

            a[i] = i;

32.

int[] arr = new int[-3];

33*

int arr[] = new int[1];

34.

int[] arr = new int[5];

for(int i=1, i<4, i++){

            arr[i] = 7;

}

35.

int[] arr = new int[5];

arr[3]  = arr[3] + arr[2];

36.

int[] arr = new int[5];

arr[3] = 4;

arr[3] += 5;

37.

int[] arr = new int[5];

for(int i=1; i<4; i--){

            arr[3] += i;

}

38.

int[] arr = new int[5];

while(arr[0]<6);{

arr[0]++;

}

System.out.println(arr[-1]);

6.

int[] arr=new int[3];

System.out.println(arr[1.5]);

7.

int[] arr=new int[3];

System.out.println(arr[1.0]);

8.

int[] arr=new int[3];

arr[1]=6.0;

9.

double[] arr=new int[3];

10.

int[] arr;

arr = new int[3];

11.

int[] arr = new int[0];

12.

boolean[][] arr;

13.

int[] arr = new int[7];

System.out.println(arr[7]);

14.

int[] arr = new int[7];

System.out.println(arr.length());

15.

int[] arr = new int[7];

System.out.println(arr.equals(arr));

16.

float[] arr = new float[3];

arr[2] = 123L;

17.

long[] arr = new long[2];

arr[2] = 34f;

18.

int[] arr = new int[2]

System.out.println("hello"+arr );

19*

int x = (new int[2])[0];

20*

(new int[2])[0]=3;

21.

int[] a = new int[];

22.

int[] short = new int[10];

int[] medium = new int[100];

int[] long = new int[10000];

23.

int[] a = new int[1000000000];

24.

int[] a = new int[10000000000];

25.

int[] a = new int[100L];

26.

int[] a = new int[5];

for(int i = 0; i <= 5; i++){

            System.out.println(a[i]);

}

27.

int[] a = new int[5];

System.out.println(a.length == 4);

28.

int[] a = new int[5];

a.length = 7;

29.

int[] a = new int[5];

if(a.length = 5)

            System.out.println("Y");

30.

int[] a = new int[3];

int i=0;

while i < 3 {

            a[i] = i;

}

31.

int[] a = new int[3];

int i=0;

while(i < 3)

            a[i] = i;

32.

int[] arr = new int[-3];

33*

int arr[] = new int[1];

34.

int[] arr = new int[5];

for(int i=1, i<4, i++){

            arr[i] = 7;

}

35.

int[] arr = new int[5];

arr[3]  = arr[3] + arr[2];

36.

int[] arr = new int[5];

arr[3] = 4;

arr[3] += 5;

37.

int[] arr = new int[5];

for(int i=1; i<4; i--){

            arr[3] += i;

}

38.

int[] arr = new int[5];

while(arr[0]<6);{

arr[0]++;

}