為什么代碼打?qū)α诉€是報錯？

public?class?HelloWorld{
????static?int?score1=86;
????static?int?score2=92;
????public?static?int?sum(){
?????return?score1+score2;
????}
????public?static?void?main(String[]?args){
????int?allScore=HelloWorld.sum();
????System.out.println("總分："?+?allScore);
????
}