随机获取用户定义的字符串

此类需要使用之前讲到的IntegerWeightRandom类；

示例：

给定"a"赋予权重100，"b"的权重为50，则getNextString()时取"a"的概率要更大；

package org.xiazdong.util;

/*给定字符串集合，设定每个字符串的权重，返回随机字符串*/
public class StringRandom {
	private String[] datas;
	private IntegerWeightRandom random = new IntegerWeightRandom();
	public StringRandom(String[]datas){
		this.datas = datas;
	}
	public void setStringWeight(int weight,int idx){
		if(datas.length>idx)
			random.addWeightNumber(weight, idx);
	}
	public String getNextString(){
		int idx = random.getNextInt();
		return datas[idx];
	}
}

测试类：

package test.org.xiazdong.util;

import org.junit.Test;

import org.xiazdong.util.StringRandom;

import junit.framework.TestCase;

public class StringRandomTest extends TestCase {

	@Test
	public void testGetNextString() {
		StringRandom random = new StringRandom(new String[] { "a", "b", "c" });
		random.setStringWeight(10, 0);
		random.setStringWeight(20, 1);
		random.setStringWeight(30, 2);
		for (int i = 0; i < 10; i++)
			System.out.println(random.getNextString());
	}
}