What should I do if java cannot find the symbol?

java cannot find symbol solution: 1. Spelling error, make sure variable name, class name, method name, etc. are spelled correctly, pay attention to case sensitivity, Java is case sensitive; 2. Not imported For classes or packages that use classes in Java’s standard library or third-party libraries, you need to use the import statement at the beginning of the source code to import these classes; 3. Compilation order issues, if one class references another class, in When compiling, you need to compile the code that references the class first; 4. Compilation environment issues, check your Java development environment to ensure correct installation and configuration, etc.

# Operating system for this tutorial: Windows 10 system, Dell G3 computer.

In Java, if you encounter a "symbol not found" error, it usually means that the compiler cannot find the definition or reference of the symbol in the code. This may be due to the following reasons:

1. Spelling errors: Please ensure that your variable names, class names, method names, etc. are spelled correctly. Pay attention to case sensitivity, Java is case sensitive.

2. Unimported classes or packages: If you use classes in Java’s standard library or third-party libraries, you need to use the import statement at the beginning of the source code to import these classes. For example, if you use the java.util.ArrayList class, you need to add import java.util.ArrayList; at the beginning of the source code.

3. Compilation order issue: If you reference another class in a class, then when compiling, you need to compile the code of the referenced class first. Otherwise, the compiler cannot find the referenced class when compiling code that references the class.

4. Compilation environment issues: Check your Java development environment to ensure that your Java development tools (such as Eclipse, IntelliJ IDEA, etc.) and Java runtime environment (JRE or JDK) are correctly installed and configured.

The following is a simple example to illustrate this problem:

public class Test {  
    public static void main(String[] args) {  
        System.out.println(new ArrayList<String>());  
    }  
}

In this example, we try to use the ArrayList class, but the java.util package is not imported, so the compiler will prompt that it cannot be found Error to ArrayList. We need to add an import statement to solve this problem:

import java.util.ArrayList;  
  
public class Test {  
    public static void main(String[] args) {  
        System.out.println(new ArrayList<String>());  
    }  
}

Now, the program can compile normally.

If you encounter this problem when working on a large project, you may need to examine your code and project structure more deeply. Sometimes, this problem can be caused by project settings, library version conflicts, or other configuration issues. In this case, you may need to check and adjust the project's build script (such as Maven or Gradle configuration files) or the development environment settings.

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