Forem: Buddika Abeykoon

Reason Why j is Always 0 in the Output

Buddika Abeykoon — Tue, 12 May 2026 02:49:05 +0000

public class Main
{
public static void main(String[] args) {
System.out.println("Start\n");
int k=0;
System.out.println("k i j");
for(int i=0; i<10; i++) {
int j=0;
System.out.println(k+" "+i+" "+j);
j++;k++;
}
System.out.println("\n\nEnd");
}

}

Start
k i j
0 0 0
1 1 0
2 2 0
3 3 0
4 4 0
5 5 0
6 6 0
7 7 0
8 8 0
9 9 0
End

j is always printed as 0 because it is declared inside the for loop. Every time the loop runs, a new variable j is created and its value starts again from 0. After printing, j increases by 1 using j++, but when the next loop iteration starts, j is reset back to 0. That is why the output always shows 0 for j.

Why This Java Loop Is Not Infinite 🤔

Buddika Abeykoon — Mon, 11 May 2026 05:31:35 +0000

public class Main
{
public static void main(String[] args) {
System.out.println("Start\n");
byte i;
for(i=0; i<10; i--) {
System.out.print(i+", ");
}
System.out.print("\b\b");
System.out.println("\n\n\"i\" value is "+i+"\n\nEnd");

}

Start

0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16, -17, -18, -19, -20, -21, -22, -23, -24, -25, -26, -27, -28, -29, -30, -31, -32, -33, -34, -35, -36, -37, -38, -39, -40, -41, -42, -43, -44, -45, -46, -47, -48, -49, -50, -51, -52, -53, -54, -55, -56, -57, -58, -59, -60, -61, -62, -63, -64, -65, -66, -67, -68, -69, -70, -71, -72, -73, -74, -75, -76, -77, -78, -79, -80, -81, -82, -83, -84, -85, -86, -87, -88, -89, -90, -91, -92, -93, -94, -95, -96, -97, -98, -99, -100, -101, -102, -103, -104, -105, -106, -107, -108, -109, -110, -111, -112, -113, -114, -115, -116, -117, -118, -119, -120, -121, -122, -123, -124, -125, -126, -127, -128,

"i" value is 127

End

This loop may look like an infinite loop because the value of i keeps decreasing and will always seem to be less than 10. However, the variable i is declared as a byte, and in Java a byte can only store values from -128 to 127. The loop starts from 0 and keeps decrementing until it reaches -128. After that, Java cannot store -129 in a byte, so the value automatically wraps around to 127 due to overflow. Once i becomes 127, the condition i < 10 becomes false, and the loop terminates. That’s why this loop is not infinite.

Why Float and Double Outputs Are Different?

Buddika Abeykoon — Fri, 08 May 2026 08:59:06 +0000

float f = Long.MAX_VALUE;
double d = Long.MAX_VALUE;

System.out.println("Float max value is : "+ f);
System.out.println("Double max value is : "+ d);

===============================================
Float max value is : 9.223372E18
Double max value is : 9.223372036854776E18
===============================================*/

When we assign Long.MAX_VALUE to float and double, both try to store a very large number. But float cannot keep many digits accurately, so Java rounds the value and shows a shorter number like 9.223372E18. double has higher precision, so it can store more digits and shows a more accurate value like 9.223372036854776E18. That’s why both outputs are different even though they come from the same value.