Java统计一个字符串在另外一个字符串出现次数的方法

package me.chunsheng.javatest;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
 * Created by wei_spring on 16/10/11.
 * 

 * 统计一个字符串在另外一个字符串出现的次数
 * 正则匹配的方法,前提字符串不是特殊字符串
 * eg:finder("adadadadauuada", "ada") 这样会统计不准确的.
 * 另外一个遍历的解决了上面那种情况.
 * 两者时间如下(纳秒为单位): 正则明显耗时,正则本就不是统计用的!!!
 * finder:3
 * finderTime:1579549
 * getCount:4
 * getCountTime:34506
 */
public class SubStringCount {
  public static void main(String[] args) {
    System.out.println("测试结果：");
    long current1 = System.nanoTime();
    System.out.println("finder:" + finder("adadadadauuada", "ada"));
    System.out.println("finderTime:" + (System.nanoTime() - current1));
    long current2 = System.nanoTime();
    System.out.println("getCount:" + getCount("adadadadauuada", "ada"));
    System.out.println("getCountTime:" + (System.nanoTime() - current2));
  }
  public static int getCount(String source, String sub) {
    int count = 0;
    int length = source.length() - sub.length();
    for (int i = 0; i