我正在嘗試編譯一位前同事的代碼，但它說(shuō)該方法unmodifiableList()不能應(yīng)用于給定類(lèi)型。Eclipse 中的代碼沒(méi)有顯示任何錯(cuò)誤。但它仍然不讓我編譯它。可能是什么錯(cuò)誤？package framework.interview.demographics;import java.util.ArrayList;import java.util.Collections;import java.util.List;import java.util.Objects;import java.util.stream.Collectors;import java.util.stream.Stream;import org.apache.xmlbeans.impl.xb.xsdschema.Public;import framework.data.people.NonReference;import framework.data.people.people;public class schedualData {    private final List<people> schedual;    private schedualData(List<people> schedual) {            this.schedual = Objects.requireNonNull(schedual);    }    public static schedualData getSchedualData(List<people> schedual) {        if(schedual.size() < 1)            throw new IllegalArgumentException("schedual must   contain at least one people");        if(Stream.of(schedual).filter(people -> (!(people instanceof NonReference))).count() != 1)            throw new IllegalArgumentException("There must be one and only one Reference between"   + "People, number, and Review");        return new schedualData(schedual);    }        //****** Getters ******\\       public people getReference() {          return schedual.stream()         .filter(people -> !(people instanceof NonReference))         .toArray(people[]::new)[0];    }       public List<NonReference> getNonReferenceschedual() {        //This is where the error is showing.         return Collections               .unmodifiableList(schedual.stream()               .filter(NonReference.class::isInstance)               .map(x -> (NonReference) x)               .collect(Collectors.toCollection     (ArrayList<NonReference>::new)));      }    public List<people> getFullschedual() {        return Collections.unmodifiableList(schedual);    }     public int size() {       return schedual.size();   }}