HTTPClient Example - Exception in thread “main” java.lang.NoSuchFieldError: INSTANCE

Question

I am using HttpClient components from Apache for the following simple program and I see the below exception:

Exception in thread \"main\" java.lang.NoSuchFieldErr         


        

Answer 1

Looking at the source code of DefaultHttpRequestWriterFactory

package org.apache.http.impl.io;

import org.apache.http.HttpRequest;
import org.apache.http.annotation.Immutable;
import org.apache.http.io.HttpMessageWriter;
import org.apache.http.io.HttpMessageWriterFactory;
import org.apache.http.io.SessionOutputBuffer;
import org.apache.http.message.BasicLineFormatter;
import org.apache.http.message.LineFormatter;

@Immutable

public class  [More ...] DefaultHttpRequestWriterFactory implements HttpMessageWriterFactory {

    public static final DefaultHttpRequestWriterFactory INSTANCE = new DefaultHttpRequestWriterFactory();

    private final LineFormatter lineFormatter;

    public  [More ...] DefaultHttpRequestWriterFactory(final LineFormatter lineFormatter) {
        super();
        this.lineFormatter = lineFormatter != null ? lineFormatter : BasicLineFormatter.INSTANCE;
    }

    public  [More ...] DefaultHttpRequestWriterFactory() {
        this(null);
    }

    public HttpMessageWriter  [More ...] create(final SessionOutputBuffer buffer) {
        return new DefaultHttpRequestWriter(buffer, lineFormatter);
    }

}

Are you sure you are using HttpCore 4.3.2? DefaultHttpRequestWriterFactory try to resolve

BasicLineFormatter.INSTANCE

field but can not find it.

Check your classpath for libraries which could contains another BasicLineFormatter class, maybe you have a HttpCore from an old version in conflict with the 4.3.2 version.