java学习StringBuilder构造方法

package com.ithema_15;
/*
    StringBuilder构造方法：
       public StringBuilder():创建一个空白可变字符串对象，不含任何内容
       public StringBuilder(String str):根据字符串内容，来创建可变字符串对象
 */
public class StringBuilderDemo01 {
    public static void main(String[] args){
        //public StringBuilder():创建一个空白可变字符串对象，不含任何内容
        StringBuilder sb = new StringBuilder();
        System.out.println("sb:" + sb);
        System.out.println("sb.length():" + sb.length());

        //public StringBuilder(String str):根据字符串内容，来创建可变字符串对象
        StringBuilder sb2 = new StringBuilder("HelloWorld");
        System.out.println("sb2:" + sb2);
        System.out.println("sb2.length:" + sb2.length());
    }
}