Java Reference
In-Depth Information
The program displays a title (line 5) on the first line in the output. The first for loop (lines
9-10) displays the numbers 1 through 9 on the second line. A dashed ( - ) line is displayed on
the third line (line 12).
The next loop (lines 15-22) is a nested for loop with the control variable i in the outer
loop and j in the inner loop. For each i , the product i * j is displayed on a line in the inner
loop, with j being 1 , 2 , 3 , . . ., 9 .
Note
Be aware that a nested loop may take a long time to run. Consider the following loop
nested in three levels:
for ( int i = 0 ; i < 10000 ; i++)
for ( int j = 0 ; j < 10000 ; j++)
for ( int k = 0 ; k < 10000 ; k++)
Perform an action
The action is performed one trillion times. If it takes 1 microsecond to perform the action,
the total time to run the loop would be more than 277 hours. Note that 1 microsecond
is one millionth (10 -6 ) of a second.
5.19
How many times is the println statement executed?
Check
Point
for ( int i = 0 ; i < 10 ; i++)
for ( int j = 0 ; j < i; j++)
System.out.println(i * j)
5.20
Show the output of the following programs. ( Hint : Draw a table and list the variables
in the columns to trace these programs.)
public class Test {
public static void main(String[] args) {
for ( int i = 1 ; i < 5 ; i++) {
int j = 0 ;
while (j < i) {
System.out.print(j + " " );
j++;
}
}
}
}
public class Test {
public static void main(String[] args) {
int i = 0 ;
while (i < 5 ) {
for ( int j = i; j > 1 ; j--)
System.out.print(j + " " );
System.out.println( "****" );
i++;
}
}
}
(a)
(b)
public class Test {
public static void main(String[] args) {
int i = 5 ;
while (i >= 1 ) {
int num = 1 ;
for ( int j = 1 ; j <= i; j++) {
System.out.print(num + "xxx" );
num *= 2 ;
}
public class Test {
public static void main(String[] args) {
int i = 1 ;
do {
int num = 1 ;
for ( int j = 1 ; j <= i; j++) {
System.out.print(num + "G" );
num += 2 ;
}
System.out.println();
i--;
}
}
}
System.out.println();
i++;
} while (i <= 5 );
}
}
(c)
(d)
 
 
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