Java Programming - Flow Control
- Flow Control - General Questions
- Flow Control - Finding the output
for(int i = 0; i < 3; i++)
{
switch(i)
{
case 0: break;
case 1: System.out.print("one ");
case 2: System.out.print("two ");
case 3: System.out.print("three ");
}
}
System.out.println("done");
The variable i will have the values 0, 1 and 2.
When i is 0, nothing will be printed because of the break in case 0.
When i is 1, "one two three" will be output because case 1, case 2 and case 3 will be executed (they don't have break statements).
When i is 2, "two three" will be output because case 2 and case 3 will be executed (again no break statements).
Finally, when the for loop finishes "done" will be output.
public class Test
{
public static void main(String args[])
{
int i = 1, j = 0;
switch(i)
{
case 2: j += 6;
case 4: j += 1;
default: j += 2;
case 0: j += 4;
}
System.out.println("j = " + j);
}
}
Because there are no break statements, the program gets to the default case and adds 2 to j, then goes to case 0 and adds 4 to the new j. The result is j = 6.
boolean bool = true;
if(bool = false) /* Line 2 */
{
System.out.println("a");
}
else if(bool) /* Line 6 */
{
System.out.println("b");
}
else if(!bool) /* Line 10 */
{
System.out.println("c"); /* Line 12 */
}
else
{
System.out.println("d");
}
Look closely at line 2, is this an equality check (==) or an assignment (=). The condition at line 2 evaluates to false and also assigns false to bool. bool is now false so the condition at line 6 is not true. The condition at line 10 checks to see if bool is not true ( if !(bool == true) ), it isn't so line 12 is executed.
public class Switch2
{
final static short x = 2;
public static int y = 0;
public static void main(String [] args)
{
for (int z=0; z < 4; z++)
{
switch (z)
{
case x: System.out.print("0 ");
default: System.out.print("def ");
case x-1: System.out.print("1 ");
break;
case x-2: System.out.print("2 ");
}
}
}
}
When z == 0 , case x-2 is matched. When z == 1, case x-1 is matched and then the break occurs. When z == 2, case x, then default, then x-1 are all matched. When z == 3, default, then x-1 are matched. The rules for default are that it will fall through from above like any other case (for instance when z == 2), and that it will match when no other cases match (for instance when z==3).
int i = 0, j = 5;
tp: for (;;)
{
i++;
for (;;)
{
if(i > --j)
{
break tp;
}
}
System.out.println("i =" + i + ", j = " + j);
If you examine the code carefully you will notice a missing curly bracket at the end of the code, this would cause the code to fail.