java--split,index,StringTokenizer比较

import java.util.StringTokenizer;

public class SplitDemo {
    //jdk8
    public static void main(String[] args){
        String s = "a,b,c";
        String[] split = s.split(",");
        for (String s1 : split) {
            System.out.println(s1);
        }
        StringTokenizer st = new StringTokenizer(s,",");
        while (st.hasMoreTokens()){
            String s1 = st.nextToken();
            System.out.println(s1);
        }
        String s2 = "a,c";
        while (true){
            int i = s2.indexOf(",");
            if (i < 0 && s2.length()<0){
                break;
            }
            if (i < 0){
                System.out.println(s2);
                break;
            }else {
                System.out.println(s2.substring(0,i));
                s2 = s2.substring(i+1);
            }
        }

        testSplit();
        testStringTokenizer();
        testIndexOf();
        //split-598
        //StringTokenizer-38
        //indexOf-4577
    }
    public static void testSplit(){
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < 1000; i++) {
            sb.append(i);
            if (i < 999){
                sb.append(",");
            }
        }
        String str = sb.toString();
        long begin = System.currentTimeMillis();
        for (int i = 0; i < 10000; i++) {
            str.split(",");
        }
        long end = System.currentTimeMillis();
        System.out.println("split" + (begin-end));
    }
    public static void testStringTokenizer(){
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < 1000; i++) {
            sb.append(i);
            if (i < 999){
                sb.append(",");
            }
        }
        String str = sb.toString();
        long begin = System.currentTimeMillis();
        for (int i = 0; i < 10000; i++) {
            StringTokenizer st = new StringTokenizer(str);
            while (st.hasMoreTokens()){
                st.nextToken();
            }
            st = new StringTokenizer(str);
        }
        long end = System.currentTimeMillis();
        System.out.println("StringTokenizer" + (begin-end));
    }
    public static void testIndexOf(){
        String s = null;
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < 1000; i++) {
            sb.append(i);
            if (i < 999){
                sb.append(",");
            }
        }
        s = sb.toString();
        String str = s;
        long begin = System.currentTimeMillis();
        for (int i = 0; i < 10000; i++) {
            while (true){
                int a = str.indexOf(",");
                if (a < 0){
                    break;
                }
                str = str.substring(a+1);
            }
            str = s;
        }
        long end = System.currentTimeMillis();
        System.out.println("indexOf" + (begin-end));
    }
}