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

I had this problem with Hadoop. It used an old version of httpclient-4.2.5.jar and httpcore-4.2.5.jar in their shared lib.

I solved this by shading parts via the maven-shade-plugin

<relocations>
    <relocation>
        <pattern>org.apache.http</pattern>
        <shadedPattern>shaded.org.apache.http</shadedPattern>
    </relocation>
</relocations>

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<HttpRequest> {

    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<HttpRequest>  [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.

Caused by: java.lang.NoSuchFieldError: INSTANCE

one of the solution of java.lang.NoSuchFieldError: INSTANCE : This happens if we have two diff version of same class in our classpath…. […], So we first find that class(one version of class) , click that class, select "build path", then we click "remove from build path" . by 333ccc333