While using the loops, we
should keep in mind for the initialization, termination and update condition.
Otherwise, there will be unexpected behavior of the program.
Infinite loop
One of the most common
mistakes while implementing any sort of looping is that that it may not ever
exit, that is the loop runs for infinite time. This happens when the condition
fails for some reason.
Java program to
illustrate infinite loop:
/**
* In this loop condition is not terminated
properly which leads to infinite
* loop.
*
* @author rajesh.dixit
*/
public class LoopPitfallTest {
public static void main(String[] args) {
// infinite loop because
termination condition is not properly used.
// condition should have
been i>0.
for (int i = 5; i > 0; i++) {
System.out.println(i);
}
int x = 5;
// infinite loop because
update statement is not provided.
while (x == 5) {
System.out.println("In the
loop");
}
}
}
OutOfMemory
Error
Another pitfall is that
you might be adding something into collection object through loop and program
can run out of memory. Please try and execute the below program, after some
time, out of memory error will be thrown.
Java program for out of
memory exception:
import java.util.ArrayList;
/**
* In this loop condition is not terminated
properly which leads to infinite
* loop.
*
* @author rajesh.dixit
*/
public class LoopPitfallTest {
public static void main(String[] args) {
ArrayList ar = new ArrayList<>();
for (int i = 0; i < Integer.MAX_VALUE; i++) {
ar.add(i);
}
}
}
Output:
Exception in thread
"main" java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:3210)
at
java.util.Arrays.copyOf(Arrays.java:3181)
