13 Common Mistakes in Java Coding to Avoid — BE AWARE !!!
- Don’t forget the case-sensitivity of Java
Some languages that are still in use today do not care about case. SQL and HTML are two examples. You may occasionally need to remind yourself that Java is case-sensitive if you’re used to using either of these languages. Java’s keyword characters are all lowercase. An “if” statement, for instance, cannot be a “IF” statement. Additionally, keep in mind to use lowercase or uppercase consistently when creating names. Java will treat a variable name that appears more than once as having wholly different names.
2. Improper value comparisons
It can be tempting to use a single equal sign when writing two values. Unfortunately, Java won’t forgive this. Always use a double equal sign. For example, write “if (inputNumber == randomNumber).”
3. A switch case construct that is missing a break.
One of the most frequent errors made by novice Java programmers is this one. Although it won’t result in a build error, the code will operate incorrectly as a result. This error frequently goes undetected until the program is launched, which makes debugging difficult. Because Java contains a feature called fall through, missing a break is a problem. Fall through results in the code execution simply moving on to the next case if there isn’t a break in the current case.
4. Using identifiers without first declaring them
All identifiers must be declared in Java before being used. You will encounter the “cant find symbol” issue if you skip this step. The spelling of the identifier as indicated when it was declared versus when it was utilized may also be the cause of this error message. Other scenarios include the class not having been imported or the variable not being used in the same context as when it was declared.
5. Using a switch statement in place of a “if…else” statement to avoid doing so — Don’t lose your time with using switch case
The way the switch statement operates is by searching through each possible scenario for the appropriate one. The cases will all be put to the test. Although overusing the switch statement may not necessarily indicate a serious error, it may indicate poor object orientation. If a “if…else” statement can be used instead, do so. As an added benefit, “if…else” statements are frequently found to be simpler to comprehend by Java developers.
6. Neglecting Existing Libraries
It’s unquestionably a mistake for Java developers to disregard the countless Java libraries that exist. Search for available libraries before creating something from scratch; many of them have been refined over time and are free to use. These could be network-related libraries like Netty or Akka, or logging libraries like logback and Log4j. Some of the libraries, like Joda-Time, are now accepted as being the norm.
The next personal experience comes from one of my earlier initiatives. The portion of the program that handles HTML escaping was entirely new. Years of successful operation were followed by a user input that sent the program into an endless loop.
7. Don’t forget the ‘break’ keyword in a Switch-Case block
These humiliating Java bugs can go undetected until they are used in actual production. Switch statements’ fallthrough behavior is frequently beneficial, but failing to use the “break” keyword when this behavior is not wanted might have severe effects. The program will output “Zero” and “One” if “break” is not present in “case 0” because the control flow inside this block will traverse the full “switch” statement until it encounters a “break.” For instance:
public static void isThisSwitchCase() {
int caseIndex = 0;
switch (caseIndex) {
case 0:
System.out.println("yes");
case 1:
System.out.println("maybe");
break;
case 2:
System.out.println("no");
break;
default:
System.out.println("have to be,1");
}
}In most cases, the cleaner solution would be to use polymorphism and move code with specific behaviors into separate classes. Java mistakes such as this one can be detected using static code analyzers
8. Forgetting to Free Resources
Java newbies should remember to release the resource once you are through utilizing it because programs frequently open files or network connections. If any exception were to be made while using these resources, similar vigilance should be exercised. One can counter that the FileInputStream contains a finalizer that calls the close() function on a garbage collection event, but since we can’t predict when a garbage collection cycle would begin, the input stream can use up system resources indefinitely. In fact, Java 7 introduces a pretty helpful and nifty statement called try-with-resources just for this situation:
private static void printLikeLinux() throws IOException {
try(FileInputStream input = new FileInputStream("ubuntu.txt")) {
int data = input.read();
while(data != -1){
System.out.print((char) data);
data = input.read();
}
}
}Any object that implements the AutoClosable interface can use this statement. It guarantees that each resource gets shut off by the statement’s conclusion.
9. Memory Leaks
Although it is comforting to not have to worry about manually allocating and clearing memory when using Java, a novice Java developer should still be aware of how memory is used in the program. Memory allocation issues could still arise. A program won’t be freed as long as it creates references to objects that are no longer required. We can still refer to this as a memory leak in a sense. Everlasting object references are the most frequent cause of memory leaks in Java because the garbage collector cannot remove objects from the heap while there are references to them.
A set of objects referencing one another might also result in circular dependencies, which makes it difficult for the garbage collector to determine whether or not these objects with cross-dependency references are necessary. When JNI is utilized, non-heap memory leaks are another problem.
10. Using static methods to access non-static members (mostly from the main method)
Because they don’t completely comprehend the distinctions between static and non-static objects in Java, inexperienced programmers frequently commit this error. It’s also interesting to see that this error most frequently occurs while attempting to access an instance variable or method in the static procedure main(). Take a look at the following code example:
public class StaticLinux { public int number; // instance variable public static void main(String[] args) { number = 30; // compile error }}
Java compiler will issue this error:
error: non-static variable number cannot be referenced from a static context
Number is an instance variable in this case, therefore the only way to access it is through an object belonging to its class, as seen in the following correction:
public class StaticExample1 { public int number; // instance variable public static void main(String[] args) { StaticExample1 obj = new StaticExample1(); obj.number = 30; }}
11. You have try to memorize code
Developers who memorize code without understanding it typically have trouble adapting it to new circumstances, which ultimately costs time and can result in errors.
Additionally, they could be unable to understand other people’s code, making collaboration challenging. Java programmers should eschew memorization in favor of concentrating on comprehending the code they are working with.
Java coding standard library classes and methods should be used as references while creating Javascript applications, and programmers should always write down all pertinent information as comments.
12. Ignoring Causes of Compile Time Errors
Compile-time errors are frequently caused by novice programming blunders made by Java developers. Syntax problems discovered by the Java compiler during compilation are known as compile-time errors.
Compile-time errors can be used to detect defects in Java source code before the program is executed, therefore Java developers should always take the time to review their code and check for them.
Using the incorrect variable type when declaring a variable or assigning incompatible data types together are frequent compile-time errors that Java designers encounter.
13. Having Null pointers
Java objects that represent a pointer to no object are called null pointers. Java code can be developed to hide the fact that a null value has been assigned to a particular variable from the programmer.
Java will attempt to access members or methods on the null object, which will result in an error, and this frequently causes runtime issues.
Java designers should exercise caution while working with Java strings, Java arrays, and Java collections since a NULL character has a Boolean value.
String firstName = “Bora”; / Line A System.out.println(firstname); / Line B /* Output will be NULL */ is a typical illustration of the Null Pointer fault.
If you are careless about checking for null values before accessing them, this could result in unexpected behavior in your Java application.
Thanks For Reading!
