Are there header files in java

The Necessary Header File for BasicHttpRequest

Generating these header files used to involve a straightforward process of executing the command line utility on class files. I’m curious about the motivation behind separating the interface from the implementation in C/C++ through header files. Additionally, I wonder why this concept wasn’t adopted by the creators of newer languages.

What’s the header file for BasicHttpRequest

I am utilizing Apache HttpComponents and wondering about the header file for BasicHttpRequest.

I am encountering an error while attempting to create a basic program.

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory at org.apache.http.impl.client.AbstractHttpClient.(AbstractHttpClient.java:159) at org.apache.http.impl.client.DefaultHttpClient.(DefaultHttpClient.java:178) at test.main(test.java:24) Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory at java.net.URLClassLoader$1.run(URLClassLoader.java:217) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205)

Which header file corresponds to this line?

HttpRequest request = new BasicHttpRequest("GET", "/",HttpVersion.HTTP_1_1); 

In contrast to C or C++, Java lacks the concept of » Header files «. The error encountered is a type of runtime error error, not a compile-time error, and it is unrelated to the absence of a «header file».

Looking at the error message:

The error message occurs when the class org.apache.commons.logging.LogFactory cannot be found. The Apache HttpComponents library has various dependencies, including Apache Commons Logging. To resolve this issue, you must download the Logging library and add the JAR file to your classpath.

In addition to Commons Logging, it is important to include all other dependencies in your classpath. Refer to the page titled «Dependencies for Apache HttpComponents» for more information.

Java socket programming header, I am trying to send a file through a java socket and receive it through another. However, this happens: Send Content: java sockets header file-transfer. Share. Improve this question. Follow edited May 22, 2010 at 6:06. Andy. asked May 22, 2010 at 5:55.

Generate JNI header files for class files in JDK 10

The Java Native Interface (JNI) includes an important component that involves connecting JVM code with native code using C headers. Previously, generating these header files was a simple process of using the command line utility javah on class files. This would automatically generate prototypes any method that had the native modifier.

Starting from Java 10, the previously utilized javah utility has been eliminated, and instead, a new flag «-h» to javac is recommended as a replacement. While this alternative works effectively when Java source files are accessible, it falls short in cases where only compiled class files are present. (The reason behind this inquiry is that I am attempting to generate JNI bindings from Scala sources. To achieve this, my current approach involves compiling the Scala sources first and then applying javah to the resultant class files.)

In a scenario where only compiled class files are accessible, is it possible to generate C header files in a manner similar to the approach utilized by javah in the past?

If generating headers for numerous files is a desperate necessity, you can opt for javap . It may be the sole choice, despite its flaws and numerous assumptions.

#!/bin/bash # FIRST_ARG - full class name (with package) # SECOND_ARG - class path CLASS_NAME=`javap -cp $2 $1 | \ grep -v "Compiled from" | \ grep "public class" | \ cut -f3 -d" " | \ awk -F"." '< print $NF >'` PACKAGE_NAME=`javap -cp $2 $1 | \ grep -v "Compiled from" | \ grep "public class" | \ cut -f3 -d" " | \ sed s/\.$$//` DIR_NAME=`echo $PACKAGE_NAME | sed 's|\.|/|g'` mkdir -p java_jni/$ JAVA_FILE_NAME="java_jni/$/$.java" echo "package $;" > $ echo "public class $ > $ javap -cp $2 $1 | grep "native" | while read line; do param=0 comma=`echo $line | grep "," | wc -l` while [ $comma -gt 0 ]; do line=`echo $line | sed "s/,/ param_$|/"` let param=param+1 comma=`echo $line | grep "," | wc -l` done line=`echo $line | sed "s/)/ param_$)/" | sed 's/|/,/g'` echo " $line" >> $ done echo ">" >> $ mkdir -p c_header javac -h c_header $

I believe there is potential to enhance its aesthetic appeal.

As I contemplate the imminent transition to Java 10, I consider the potential scenarios where I might encounter missing Java source code. In light of this, having a tool readily available seems like a prudent idea, just in case.

JNI header files can be generated using gjavah.

To resolve the issue, it is recommended to simply install JDK8. There is no need to uninstall JDK10; instead, you can modify the environment variable.

Java Source File Structure, Explanation: Java allows us to name the Java source file with anything if there is not a single class that is declared as public. But if there is a class that is declared as public, the name of the Java source file must be the same as the public class name. The Java source file extension must be .java.

Why does C/C++ have header files unlike other languages like C# and Java? [duplicate]

What was the motivation behind separating the interface from the implementation in C/C++ using header files, and why haven’t other language authors adopted this concept in newer languages? Does the absence of this concept imply its inadequacy?

EDIT: My question is not about why c/c++ use header files — I’m inquiring about the reason behind the absence of this concept in newer languages like Java, etc.

During the design of the C language, there was a need to optimize processing time and memory usage due to the limited resources of computers at that time. Instead of requiring multiple passes over the source code or constructing a large data structure in memory before emitting compiled code, a design was preferred where the compiler could read the source file and compile it «on the fly» with minimal resource usage. Header files provide a way to declare and use symbols while their definitions may be located later in the source code or even in a different file or external library.

In the design of newer languages like C# and Java, the focus was on prioritizing programmer convenience over optimizing the compiler’s resource usage. Additionally, numerous modern C compilers now employ multiple passes since it is not feasible to apply multiple code optimizations in just one pass. Consequently, adopting a similar design for new languages does not yield significant benefits in today’s context.

In addition to their other advantages, header files provide the ability to separate interface from implementation. This allows the header file to function as an API documentation without revealing implementation specifics.

I’m uncertain if this question is suitable for Stackoverflow, however:

I value the clarity of having separate .h and .cpp files when writing a class, as it provides several advantages.

When my class is used by others, they simply have to refer to the .h file without any confusion caused by internal code within the class’s methods. This function is invoked similarly to [previous method], and the accompanying comments provide a clear explanation of its functionality, eliminating the need to understand the remaining code.

When reviewing my code, the separation of .h and .cpp files enables me to compare and contrast. If I have an incomplete method in the .cpp file that I ultimately don’t need, there will be a discrepancy between the two files. Therefore, I can rely on the more comprehensible .h file for review purposes to determine if there are any errors in the .cpp file.

Image — Java BMP Header files, Java BMP Header files. Ask Question Asked 9 years, 4 months ago. Modified 9 years, 4 months ago. Viewed 4k times 1 1. I try to make a BMP file from BufferedImage. Here is function with that I try to write the header and pixels in bmp file. I have a mistake but I

Java, JNI and C++: How do I generate a header file from native method declarations?

How can I generate a header file from native method declarations in C++?

I am currently working on a Java project that utilizes JNI to communicate with C++ code. The current challenge I am facing is the need to incorporate new methods. Initially, I began by declaring these native methods in the Java code . However, I now find myself in a position where I must regenerate the header file for the JNI methods. Since I am using Eclipse, I am unsure about the steps required to accomplish this.

Although Eclipse does not have this feature integrated, it can be easily implemented.

1. To create an Ant file (code included), use File » New. » XML File and incorporate it into your project.
2. To include the Ant file as a build step, use Project » Properties » Builders » New. » Ant Builder . Set the Refresh option to «project» to ensure that the generated files are visible in the project. Place the build step after the Java Builder step, as javah requires access to the compiled class files.

By listing the relevant classes in the Ant file, you can ensure that your Java code always has the latest header files.

The Ant script can be enhanced with more advanced features, but the provided example is adequate.

I used to do it using command line.

• go to the source file directory.
• javac filename.java to generate filename.class file.
• javah filename to generate filename.h file.

For additional assistance, please consult javac and javah.

How about the JDK utility called «javah»?

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