public class STR {
private static String Builderrud(int a){
StringBuilder builder= new StringBuilder(); //调用StringBuilder类
for (int j=0;j<a;j++){
builder.append(j); //Builder类的追加功能
}
String builder1=String.valueOf(builder);
System.out.printf(builder1); //调试打印
return builder1;
};
public static void main(String[] args) { //主函数调用
Builderrud(40); //40位随机数,要包含字母的话可修改追加
}
}