最近马上讲API里的StringBuffer类,看了一下老毕的视频,于是用StringBuilder试了一下,犯了个低级错误。错误代码如下
package javaSE2;
public class StringBuilder {
public static void main(String[] args){
StringBuilder builder = new StringBuilder();
builder.append("a");
}
报错是The method append(String) is undefined for the type StringBuilder