Identifier expected java ошибка

Posted by Marta on November 21, 2021 Viewed 91034 times

In this article you will learn how to fix the java error: identifier expected to get a better understanding of this error and being able to avoid in the future.

This error is a very common compilation error that beginners frequently face when learning Java. I will explain what is the meaning of this error and how to fix it.

What’s the meaning of Identifier Expected error?

The identifier expected error is a compilation error, which means the code doesn’t comply with the syntax rules of the Java language. For instance, one of the rules is that there should be a semicolon at the end of every statement. Missing the semicolon will cause a compilation error.

The identifier expected error is also a compilation error that indicates that you wrote a block of code somewhere where java doesn’t expect it.

Here is an example of piece of code that presents this error:

public class Example {
	System.out.println("Hello");
}

If you try to compile this class, using the javac command in the terminal, you will see the following error:

Output:

Example.java:5: error: <identifier> expected
    System.out.println("Hello");
                      ^
Example.java:5: error: illegal start of type
    System.out.println("Hello");
                       ^

This error is slightly confusing because it seems to suggest there is something wrong with line 2. However what it really means is that this code is not in the correct place.

How to Fix it

We have seen what the error actually means, however how could I fix it? The error appears because I added some code in the wrong place, so what’s the correct place to right code? Java expects the code always inside a method. Therefore, all necessary to fix this problem is adding a class method and place the code inside. See this in action below:

public class Example {

    public void print() {
        System.out.println("Hello");
    }
}

The code above will compile without any issue.

Another example

Here is another example that will return the identifier expected error:

public class Example {

    public void print() {
        System.out.println("Hello");
    }

    Example e = new Example();
    e.print(); // Here is the error
}

Output:

Example.java:10: error: <identifier> expected
    e.print();
           ^

As before, this compilation error means that there is a piece of code: e.print() that is not inside a class method. You might be wondering, why line 7 ( Example e = new Example(); ) is not considered a compilation error? Variable declarations are allowed outside a method, because they will be considered class fields and their scope will be the whole class.

Here is a possible way to fix the code above:

public class Example {

    public void print() {
        System.out.println("Hello");
    }

    Example e = new Example();

    public void method2(){
        e.print();
    }
}

The fix is simply placing the code inside a method.

Conclusion

To summarise, this article covers how to fix the identifier expected java error. This compilation error will occur when you write code outside a class method. In java, this is not allow, all code should be placed inside a class method.

In case you want to explore java further, I will recommend the official documentation

Hope you enjoy the tutorial and you learn what to do when you find the identifier expected error. Thanks for reading and supporting this blog.

Happy coding!

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1. Understanding <identifier> expected Error in Java
2. Example 1: When Parameters in a Method Are Missing Data Type or Name
3. Example 2: When the Expression Statements Are Misplaced
4. Example 3: When Declaration Statements Are Misplaced
5. Conclusion

In this article, we will learn about Java’s <identifier> expected error.

Understanding <identifier> expected Error in Java

The <identifier> expected is the most common Java compile-time error faced by novice programmers. This error occurs when a method parameter does not have a data type or name declared or when an expression statement is written outside a method, a constructor, or an initialization block.

In Java, an identifier is a sequence of one or more characters where the 1st character must be a letter or $ or _, and the subsequent characters can be letters, digits, $ or _.

These identifiers are used to name a variable, a method, a class, a package, an interface, etc.

When the Java code is compiled initial phase involves lexical analysis of the program. Here the program is categorized into tokens, and all the tokens, including identifiers, are verified against a set of grammar rules.

And whenever as per grammar rules, an identifier is expected, but it’s not present, and something else is found in its place compiler raises the <identifier> expected error. Angle brackets here signify a reference to the token objects.

Let’s look at some examples to understand it better now.

Example 1: When Parameters in a Method Are Missing Data Type or Name

Parameters inside a method must have data followed by the variable name, which is an identifier; missing either of those will inevitably raise the <identifier> expected error.

1. Data of the parameter is missing

   public class Demo
   {
       public static int square(x)
       {
           return x*x;
       }
   
       public static void main(String[] args)
       {
   
           System.out.println(square(10));
   
       }
   }
   

   Output:

   square.java:9: error: <identifier> expected
   public static int square(x) {
           	        	  ^
   1 error
   

   If we observe the error above, we see that variable x is missing the data type. If we give the data type for it, it will work properly.

   public class Demo
   {
   
           public static int square( int x)
           {
               return x*x;
           }
   
           public static void main(String[] args)
           {
   
               System.out.println(square(10));
   
           }
   }
   

   Output:

2. The parameter’s data type is the identifier; the variable name is missing here.

   public class Demo
   {
   
       public static int square(int)
       {
           return x*x;
       }
   
       public static void main(String[] args)
       {
   
           System.out.println(square(10));
   
       }
   }
   

   Output:

   square.java:9: error: <identifier> expected
   public static int square(int) {
           	        	   ^
   1 error
   

   If we observe the error above, we can clearly see that we specified the data type but didn’t attach any variable name.

   public class Demo
   {
   
           public static int square( int x)
           {
           	return x*x;
           }
   
           public static void main(String[] args)
           {
   
           	System.out.println(square(10));
   
           }
   }
   

   Output:

Example 2: When the Expression Statements Are Misplaced

The compiler raises an error when an expression statement is written outside a method, a constructor or an initialization block <identifier> expected.

Example code:

public class Demo
{
    private String name;
    name = "Naruto";
    System.out.println(name);
}

Output:

Demo.java:9: error: <identifier> expected
  name = "Naruto";
      ^
Demo.java:10: error: <identifier> expected
  System.out.println(name);
                    ^
Demo.java:10: error: <identifier> expected
  System.out.println(name);
                        ^
3 errors

If we observe the error above, the error occurs because the statements are not enclosed within a function or a constructor. Let’s write these statements inside a method named print.

public class Demo {

    private String name;

    public void print()
    {
        name = "Naruto";
        System.out.println(name);
    }

    public static void main(String[] args) {

        Demo obj = new Demo();
        obj.print();

    }
}

Output:

Example 3: When Declaration Statements Are Misplaced

This is rare but not unheard of when working with try-with-resources statements. All these statements require that any closable resource be declared immediately after the try keyword.

If the resource variable is declared outside the try-with-resources statement, then the <identifier> expected error might be raised by the compiler (as compiler to compiler, this may vary).

Example code: Here, the closable resource is BufferedReader.

import  java.io.*;


public class Demo
{

        public static void main(String[] args) {
        StringBuilder obj = new StringBuilder();
        BufferedReader br = null;

        try (br = new BufferedReader(new InputStreamReader(System.in))){
            String lines = "";
            while (!(lines = br.readLine()).isBlank()) {
                obj.append(lines);
            }
        } catch(Exception e){
            e.printStackTrace();
        }


    }

}

Output:

Demo.java:13: error: <identifier> expected
        try (br = new BufferedReader(new InputStreamReader(System.in))) {
              ^
1 error

The error will be resolved if we declare the BufferedReader obj inside the try block.

import  java.io.*;


public class Demo
{

    public static void main(String[] args) {
        StringBuilder obj = new StringBuilder();

        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))){

            String lines = "";
            while (!(lines = br.readLine()).isBlank()) {
                obj.append(lines);
            }
        } catch(Exception e){
            e.printStackTrace();
        }


    }

}

Conclusion

In this article, we learned about why the <identifier> expected error had been raised by the compiler and how it’s the most common compile-time error faced by newbies. We also looked at different examples analyzing the cases when this error was raised.

I’am glad to see peaple learning Java, and i’am happy to see peaople helping the juniors.
When i see your code, my first advise is to get a good IDE like Eclipse, IntelliJ or Netbeans, it will help you to see quickly the compilation errors.

My second advise is to get a look to the dev norms, as a junior i think is the first methodology you have to study to have a comprehensive and maintainable code.

for example please avoid adding several blank lines between the method signature and the first statment.
I barely touched your code to get it works.
I hope you will enjoy Java.

public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        intro(input);
        time(input);
    }

    public static void intro(Scanner input) {
        System.out.println("Welcome");
        System.out.println("What is your name");

        String name = input.nextLine();
        System.out.println("Nice to meet you, " + name + " where are you travelling to?");
        String dest = input.nextLine();
        System.out.println("Great! " + dest + " sounds like a great trip");
    }

    public static void time(Scanner input) {
        int hours, minutes;
        float perd, perdc, change;

        System.out.println("How many days are you going to spend travelling?");

        int days = input.nextInt();

        hours = days * 24;
        minutes = hours * 60;

        System.out.println("How much money in USD are you going to spend?");

        Float money = input.nextFloat();
        perd = money / days;

        System.out.println("What is the three letter currency symbol of your destination?");

        String curr = input.nextLine();

        System.out.println("How many " + curr + " are there in 1USD?");

        Float ex = input.nextFloat();
        change = money * ex;
        perdc = perd * ex;

        System.out.println("If you are travelling for " + days + " that is the same as " + hours + " or " + minutes + " minutes");
        System.out.println("If you are going to spend " + money + " $USD that means per day you can spend upto $" + perd + " USD");
        System.out.println("Your total budget in " + ex + " is " + change + ex + " ,which per day is  " + perdc + curr);
    }