A fluent API for ContentResolver#query

Query.java

package test;

import java.util.ArrayList;

import android.content.ContentResolver;
import android.database.Cursor;
import android.net.Uri;

/**
 * Just an incomplete POC .... MANY operators missing (IN,BETWEEN, ...) AND MANY MORE!
 * 
 * @author b.quentin
 * 
 */
public class Query {

    public interface QueryBuilder {

	public interface UnfinishedWhere {

	    public QueryBuilder.Where ne(String value);
	    
	    public QueryBuilder.Where eq(String value);

	    public QueryBuilder.Where le(String value);

	    public QueryBuilder.Where l(String value);

	    public QueryBuilder.Where g(String value);

	    public QueryBuilder.Where ge(String value);

	    public QueryBuilder.Where like(String value);

	}

	public interface Where {
	    public QueryBuilder and();

	    public QueryBuilder or();

	    public QueryBuilder.FinishedQueryBuilder orderBy(String orderBy);

	    public Query build();

	}

	
	public interface FinishedQueryBuilder {
		public Query build();
	}
	
	public QueryBuilder select(String... columns);

	public QueryBuilder.UnfinishedWhere where(String column);
	

	public Query build();

	public Where where(Where q);

    }

    private QueryBuilderImpl queryBuilderImpl;

    private Query(QueryBuilderImpl queryBuilderImpl) {
	this.queryBuilderImpl = queryBuilderImpl;
    }

    public static QueryBuilder create() {
	return new QueryBuilderImpl();
    }

    public Cursor execute(ContentResolver contentResolver, Uri contentUri) {
	String[] projection = queryBuilderImpl.fields;
	String selection = queryBuilderImpl.where.toString();
	String[] selectionArgs = queryBuilderImpl.params.toArray(new String[queryBuilderImpl.params.size()]);
	String sortOrder = queryBuilderImpl.sortOrder;
	
	return contentResolver.query(contentUri, projection, selection, selectionArgs, sortOrder);
    }

    public static class QueryBuilderImpl implements QueryBuilder, QueryBuilder.UnfinishedWhere, QueryBuilder.Where, QueryBuilder.FinishedQueryBuilder {

	private String[] fields;
	private String sortOrder;
	private StringBuffer where = new StringBuffer();
	private ArrayList<String> params = new ArrayList<String>();

	@Override
	public QueryBuilder select(String... columns) {
	    fields = columns;
	    return this;
	}

	
	@Override 
	public Where where(Where qb){
	    QueryBuilderImpl w = (QueryBuilderImpl) qb;
	    where.append("(");
	    where.append(w.where.toString());
	    where.append(")");
	    params.addAll(w.params);
	    
	    return this;
	}
	
	@Override
	public UnfinishedWhere where(String column) {
	    where.append(" ");
	    where.append(column);
	    return this;
	}

	@Override
	public QueryBuilder.FinishedQueryBuilder orderBy(String orderBy) {
	    this.sortOrder = orderBy;
	    return this;
	}

	@Override
	public QueryBuilder and() {
	    where.append(" AND ");
	    return this;
	}

	@Override
	public QueryBuilder or() {
	    where.append(" OR ");
	    return this;
	}

	
	@Override
	public Where ne(String value) {
	    params.add(value);
	    where.append("<>?");
	    return this;
	}
	
	@Override
	public Where eq(String value) {
	    params.add(value);
	    where.append("=?");
	    return this;
	}

	@Override
	public Where le(String value) {
	    params.add(value);
	    where.append("<=?");
	    return this;
	}

	@Override
	public Where l(String value) {
	    params.add(value);
	    where.append("<?");
	    return this;
	}

	@Override
	public Where g(String value) {
	    params.add(value);
	    where.append(">?");
	    return this;
	}

	@Override
	public Where ge(String value) {
	    params.add(value);
	    where.append(">=?");
	    return this;
	}

	@Override
	public Where like(String value) {
	    params.add(value);
	    where.append("LIKE ? ");
	    return this;
	}

	@Override
	public Query build() {
	    return new Query(this);
	}

    }

}