Day14_StringBuffer和StringBuilder

StringBuffer和StringBuilder

package com.oop.Demo11;

/**
 * StringBuffer和StringBuilder的使用
 * 和String区别（1）效率比String高（2）比String节省内存空间
 */
public class Demo05 {
    public static void main(String[] args) {
        //StringBuffer sb=new StringBuffer ();
        StringBuilder sb=new StringBuilder ();
        //1 append();追加
        sb.append ("java是最好的语言");
        //toString 方法把它变回字符串
        System.out.println (sb.toString ());
        sb.append ("aaa");
        System.out.println (sb.toString ());
        //2.insert();添加
        sb.insert(0,"我在最前面");
        System.out.println (sb.toString ());
        //3.replace();
        sb.replace (0,5,"hello");
        System.out.println (sb.toString ());
        //4.delete();删除
        sb.delete (0,5);
        System.out.println (sb.toString ());
        //清空
        sb.delete (0,sb.length ());
        System.out.println ("清空"+sb.length ());
    }
}