Question

我是java的新手，我有一个非常常见的编译错误。我尝试了其他解决方案，但没有任何对我有用。我必须创建一个日历，这是我的Date.java的片段：

package edu.kit.informatik.calendar;
public final class Date {

private final int year; // Placeholder value
private final int month; // Placeholder value
private final int day; // Placeholder value

public int dayOfYear;

public Date(int year, int month, int dayOfMonth){
    this.year  = year;
    this.month  = month;
    this.day  = dayOfMonth;
}   
public DateTime atTime(Time time){
    DateTime dateTime = new DateTime(this, time);
    return dateTime;
}
public int getYear(){
    return year;
}
public int getMonthValue(){
    return month;
}
public int getDayOfMonth(){
    return day;
}   
public int getMonth(){
    return Month.ofIndex(month);
}

在另一个名为DateTime.java的文件中，我有这样的东西：

package edu.kit.informatik.calendar;

public final class DateTime {

private final Date date; // Placeholder value
private final Time time; // Placeholder value

public DateTime(Date date, Time time){
    this.date = date;
    this.time = time;
}

public Date getDate(){
    return date;
}
public Time getTime(){
    return time;
}

public int getYear(){
    return date.getYear();
}
public int getMonthValue(){
    return date.getMonthValue();
}
public Month getMonth(){
    return date.getMonth();
}
public int getDayOfYear(){
    return date.getDayOfYear();
}
public int getDayOfMonth(){
    return date.getDayOfMonth();
}
public int getHour(){
    return time.getHour();
}
public int getMinute(){
    return time.getMinute();
}
public int getSecond(){
    return time.getSecond();
}

public String toString(){
    return date.toString() + "T" + time.toString();
}
}

然后还有另一个名为Time.java的文件，但它看起来就像另外两个。

当我尝试编译DateTime.java

时

C:\Users\Marcel\Documents\Programmieren\assignment01-     solution\TaskE\edu\kit\informatik\calendar>javac DateTime.java
DateTime.java:12: error: cannot find symbol
private final Date date; // Placeholder value
              ^
symbol:   class Date
location: class DateTime
DateTime.java:13: error: cannot find symbol
    private final Time time; // Placeholder value
                  ^
  symbol:   class Time
location: class DateTime
DateTime.java:15: error: cannot find symbol
      public DateTime(Date date, Time time){
                      ^
  symbol:   class Date
  location: class DateTime
DateTime.java:15: error: cannot find symbol
        public DateTime(Date date, Time time){
                        ^
  symbol:   class Time
  location: class DateTime
DateTime.java:20: error: cannot find symbol
        public Date getDate(){
               ^
  symbol:   class Date
  location: class DateTime
  DateTime.java:23: error: cannot find symbol
        public Time getTime(){
               ^
symbol:   class Time
location: class DateTime
DateTime.java:33: error: cannot find symbol  
    public Month getMonth(){
           ^
symbol:   class Month
location: class DateTime
7 errors

Answer 1

当您尝试编译DateTime.java时，它对您的Date类一无所知。如果使用另一个，你需要编译它们：

javac DateTime.java Date.java

Answer 2

这听起来像是类路径/构建路径问题。由于您尚未设置$ CLASSPATH且未使用-cp选项，因此编译时应位于TaskE目录中。

或者（如@chryslis所说）使用IDE或构建工具（如Maven或Ant）来构建，并消除手动键入javac命令的不可预测性。

Java-“未找到符号”

2 个答案: