Java OCA OCP Practice Question 1558

Question

Given the following declaration: 

int [][] twoD =  {  { 1, 2, 3} ,  { 4, 5, 6, 7},  { 8, 9, 10  }  };

What will the following lines of code print? 

System.out.println (twoD [1].length);
System.out.println (twoD [2].getClass ().isArray ());
System.out.println (twoD [1][2]);

Select 1 option 

A. 4//from  w  w  w  .j av  a  2 s . com
   true
   6

B. 3
   true
   3

C. 3
   false
   3

D. 4
   false
   6



Correct Option is  : A

Note

In Java, array numbering starts from 0. So in this case, twoD is an array containing 3 other arrays.

twoD[0] is { 1, 2, 3} , twoD[1] is { 4, 5, 6, 7}, and twoD[2] is { 8, 9, 10 }.

Thus, twoD[1].length is 4 and twoD[1][2] is the third element in { 4, 5, 6, 7}, which is 6.

In Java, arrays are just like regular Objects and arrays of different types have different class names.

For example, the class name of an int [] is [I and the class name for int [][] is [[I.

For array classes, the isArray() method of a Class returns true.

For example, twoD.getClass().isArray() will return true.

There are a few questions in the exam that require you to know about this.




PreviousNext

Related