String 与StringBuffer比较

Posted 2020-07-24 watchfree

package String比较;
/*
 * String 与StringBuffer比较
 * String 不可变,一旦赋值，就不能被修改
 * StringBuffer可变的字符串。
 * StringBuffer的追加效率更高
 */

public class Test8 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str = "abc";
        str.replace("a", "b");
        System.out.println(str);// abc
        StringBuffer sbf = new StringBuffer("abc");
        sbf.replace(0, 1, "de");
        System.out.println(sbf);// debc

        String s1 = "chinasofti";
        int time = 10000;
        @SuppressWarnings("unused")
        String tempstr = "";
        long start1 = System.currentTimeMillis();
        for (int i = 0; i < time; i++) {
            tempstr += s1;
        }
        long end1 = System.currentTimeMillis();
        System.out.println("String：" + (end1 - start1) + "ms");// 876ms

        StringBuffer tempsbf = new StringBuffer();
        long start2 = System.currentTimeMillis();
        for (int i = 0; i < time; i++) {
            tempsbf.append(s1);
        }
        long end2 = System.currentTimeMillis();
        System.out.println("StringBuffer:" + (end2 - start2) + "ms");// 1ms
    }

}