StringBuffer sb = new StringBuffer("sdfs");
sb.append("sdf");
sb.append(2);//这行会报错。。。。The type java.lang.CharSequence cannot be resolved. It is indirectly referenced from required .class files
//----------------------------
String s1 = "dg";
StringBuffer s2 = new StringBuffer();
for(int x=0;x<s1.length();x++){
String y =String.ValueOf(s1.charAt(x));//这个会报错
String y = (String)s1.charAt(x);//这个也会报错
s2.insert(x,s1.charAt(x));//这个还他妈的会报错!!!!!!!
哭晕在客厅。。。满头大汗,,,