Java code fails to run, how to solve it?

Java code fails to run, how to solve it?

In the process of writing and running Java code, it is inevitable that you will encounter various errors that cause the program to fail to execute normally. This article will introduce some common Java code running failure problems and give solutions, hoping to help readers better troubleshoot errors and run the program smoothly.

1. Compilation errors

Compilation errors are one of the most common problems, usually caused by syntax errors. For example, missing semicolons, mismatched brackets, undeclared variables, etc. The following is an example of a common compilation error:

public class Test {
    public static void main(String[] args) {
        System.out.println("Hello World")
    }
}

In the above code, a semicolon is missing, causing an error during compilation. The solution is simple, just add a semicolon after the "System.out.println("Hello World")" statement.

2. Runtime errors

In addition to compilation errors, another common error is runtime errors. This kind of error usually occurs during program execution, such as null pointer exception, array out of bounds, etc. The following is an example:

public class Test {
    public static void main(String[] args) {
        int[] array = new int[3];
        System.out.println(array[3]);
    }
}

In the above code, the array exceeds the bounds and causes the program to report an error. The solution is to check whether the length of the array is sufficient and make sure that the array elements are not out of bounds when accessed.

3. Dependency error

Sometimes the program depends on external libraries or packages. If the dependencies are not configured correctly, the program will not execute normally. The following is an example:

import org.apache.commons.lang3.StringUtils;

public class Test {
    public static void main(String[] args) {
        String str = "Hello";
        System.out.println(StringUtils.upperCase(str));
    }
}

In the above code, the StringUtils class provided by the Apache Commons Lang library is used. If the library is not configured, the program cannot execute correctly. The solution is to add a dependency on the Apache Commons Lang library to the project.

4. Network connection error

When performing network programming, the program may not execute properly due to network connection problems. Here is a simple example:

import java.net.URL;
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Test {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://www.example.com");
            BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

In the above code, the program attempts to read content from a URL. If there is a problem with the network connection, it will cause the program to error. The solution is to check whether the network connection is normal and ensure that the target address can be accessed normally.

Conclusion

The above are some common problems and solutions to the failure of Java code to run. When writing and running Java code, it is recommended to pay more attention to the quality and logic of the code, troubleshoot errors in time and make adjustments to ensure that the program can execute normally. I hope that readers can better solve the problem of Java code failure through the content of this article.

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