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Pig having some Built-in functions, we can use that Built-in functions for our Pig Script without adding any extra code but sometimes user requirement is not available in that built-in functions at that time user can write some own custom user-defined functions called UDF (user defined function).Here is the simple steps of How To Write Pig UDF Example In Java.

Steps to create Pig UDF

Step 1:-

Open your Eclipse and Create a Java Class Name like first.java

Step 2:-

You should add jar files to that Project folder like

Right Click on project —> Build Path —> Configure Build Path —> Libraries —> Add External Jars —> Select Hadoop and Pig Lib folder Jars files and Add other Jars files In Hadoop folder —–> Click Ok.

Step 3:-

Now your Pig java program is supported in your eclipse without any errors.The basic step in Pig UDF is

public class first extends EvalFunc<Class DataType> and you return the value.

package mypro;

import java.io.IOException;
import org.apache.pig.EvalFunc;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.util.WrappedIOException;

public class Ucfirst extends EvalFunc<String> {
    public String exec(Tuple input) throws IOException {
        if (input.size() == 0)
            return null;
        try {
            String str = (String) input.get(0);
            char ch = str.toUpperCase().charAt(0);
            String str1 = String.valueOf(ch);
            return str1;

        } catch (Exception e) {
        
            throw WrappedIOException.wrap(
                    "Caught exception processing input row ", e);
        }
    }
}