返回类型——方法返回值的数据类型,如果方法不返回值,则返回 void。
http://download.oracle.com/javase/tutorial/java/javaOO/methods.html http://download.oracle.com/javase/tutorial/java/javaOO/methods.html
好吧,那么..这是我的问题:
public class EnumTest {
Day day;
public EnumTest(Day day) {
this.day = day;
}
public void tellItLikeItIs() {
switch (day) {
case MONDAY: System.out.println("Mondays are bad.");
break;
case FRIDAY: System.out.println("Fridays are better.");
break;
case SATURDAY:
case SUNDAY: System.out.println("Weekends are best.");
break;
default: System.out.println("Midweek days are so-so.");
break;
}
}
public static void main(String[] args) {
EnumTest firstDay = new EnumTest(Day.MONDAY);
firstDay.tellItLikeItIs();
EnumTest thirdDay = new EnumTest(Day.WEDNESDAY);
thirdDay.tellItLikeItIs();
EnumTest fifthDay = new EnumTest(Day.FRIDAY);
fifthDay.tellItLikeItIs();
EnumTest sixthDay = new EnumTest(Day.SATURDAY);
sixthDay.tellItLikeItIs();
EnumTest seventhDay = new EnumTest(Day.SUNDAY);
seventhDay.tellItLikeItIs();
}
}
http://download.oracle.com/javase/tutorial/java/javaOO/enum.html http://download.oracle.com/javase/tutorial/java/javaOO/enum.html
如果没有 void,上面的代码将无法工作。
Exception in thread "main" java.lang.Error: Unresolved compilation problems:
The method tellItLikeItIs() is undefined for the type EnumTest
我错过了什么?
为什么里面有一个空洞?
它确实返回一个字符串?
你的意思是tellItLikeItIs
方法?是的,您必须指定void
指定该方法doesn't返回任何东西。所有方法have指定返回类型,即使它是void
.
它当然不会返回字符串 - 看,任何地方都没有 return 语句。不太清楚你为什么这么想is返回一个字符串。它是printing字符串到控制台,但这与从方法返回一个字符串不同。
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