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a useful java tools based on java collection stream framework

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package com.github.paganini2008.devtools.beans.streaming;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Collectors;

import com.github.paganini2008.devtools.collection.ListUtils;
import com.github.paganini2008.devtools.jdbc.ResultSetSlice;

/**
 * 
 * Select
 * 
 * @author Fred Feng
 * @version 1.0
 */
public class Select implements Selectable {

	private List content;

	Select(List content) {
		this.content = content;
	}

	public static  Select from(Collection content) {
		return new Select(content instanceof List ? (List) content : new ArrayList(content));
	}

	public Selectable filter(Predicate predicate) {
		content = content.stream().filter(predicate).collect(Collectors.toList());
		return this;
	}

	public Selectable distinct() {
		content = content.stream().distinct().collect(Collectors.toList());
		return this;
	}

	public Selectable orderBy(Sort sort) {
		content.sort(sort);
		return this;
	}

	public  Groupable groupBy(Function function, String attributeName) {
		return new Groups(content).groupBy(function, attributeName);
	}

	public List list(int maxResults, int firstResult) {
		return ListUtils.slice(content, maxResults, firstResult);
	}

	public int totalCount() {
		return content.size();
	}

	public  ResultSetSlice setTransformer(Transformer transformer) {
		return new MemoryResultSetSlice(content, transformer);
	}

}