skeleton for GenericUDF

SkeletonUDF.java

package somewhere;

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentLengthException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;

@Description(name = "skeleton",
        value = "_FUNC_(something) - Returns something")
public class SkeletonUDF extends GenericUDF {
    // declare OIs
    
    @Override
    public ObjectInspector initialize(ObjectInspector[] OIs) throws UDFArgumentException {
        if (OIs.length != 0) {
            throw new UDFArgumentLengthException("Specify  arguments.");
        }
        
        if (/*check type of OIs*/) {
            throw new UDFArgumentTypeException(0, "Only  type argument is acceptable but "
                    + OIs[0].getTypeName() + " was passed as ``");
        }
    
        // init OIs
        
        return null;
    }

    @Override
    public Object evaluate(GenericUDF.DeferredObject[] dObj) throws HiveException {
        // process and return writable value
        
        return null;
    }
    
    @Override
    public String getDisplayString(String[] children) {
        final StringBuilder sb = new StringBuilder();
        sb.append("skeleton");
        sb.append("(");
        if (children.length > 0) {
            sb.append(children[0]);
            for (int i = 1; i < children.length; i++) {
                sb.append(", ");
                sb.append(children[i]);
            }
        }
        sb.append(")");
        return sb.toString();
    }
}