這幾天碰到了編譯失敗的嚴重問題，所以只好痛下心來好好研究看看：
我的OS:Windows XP
有設PATH：C:Program FilesJavajdk1.6.0_07bin
package要用的程式碼Fish.java：
package water;
public class Fish {
public static String name = “小金”;
public static String type = “金魚”;
public static String color = “金”;
public static void skill() {
System.out.println(“吐泡泡”);
}
}
import 要用的程式碼PetStore3.java：
import water.*;
public class PetStore3 {
public static void main(String[] args) {
String fishName = Fish.name;
String fishKind = Fish.type;
String fishColor = Fish.color;
System.out.println(“我有一隻優雅的” + fishKind +
“, 名叫” + fishName +
“, 他的顏色是”+fishColor+” 色的.”);
System.out.println(“每當他肚子餓的時候都會”);
Fish.skill();
}
}
分14種狀況測試，這真的很好玩，結果有令人恍然大悟的感覺：
| Fish.java位置 | classpath設定 | PetStore3.java位置 | 結果 |
| c:water | .; | c: | OK |
| c:water | .; | c:water | PetStore3.java:1: package water does not exist import water.*; ^ PetStore3.java:5: cannot access Fish bad class file: .Fish.class class file contains wrong class: water.Fish Please remove or make sure it appears in the correct subdirectory of the classpa th. String fishName = Fish.name; ^ 2 errors |
| c:water | .;c:; | c:water | PetStore3.java:5: cannot access Fish bad class file: d:sourcejavawaterFish.class class file contains wrong class: water.Fish Please remove or make sure it appears in the correct subdirectory of the classpa th. String fishName = Fish.name; ^ 1 error |
| c:water | .;c:; | c: | OK |
| c:sourcewater | .; | c: | PetStore3.java:1: package water does not exist import water.*; ^ PetStore3.java:5: cannot find symbol symbol : variable Fish location: class PetStore3 String fishName = Fish.name; ^ PetStore3.java:6: cannot find symbol symbol : variable Fish location: class PetStore3 String fishKind = Fish.type; ^ PetStore3.java:7: cannot find symbol symbol : variable Fish location: class PetStore3 String fishColor = Fish.color; ^ PetStore3.java:12: cannot find symbol symbol : variable Fish location: class PetStore3 Fish.skill(); ^ 5 errors |
| c:sourcewater | .;c:; | c: | PetStore3.java:1: package water does not exist import water.*; ^ PetStore3.java:5: cannot find symbol symbol : variable Fish location: class PetStore3 String fishName = Fish.name; ^ PetStore3.java:6: cannot find symbol symbol : variable Fish location: class PetStore3 String fishKind = Fish.type; ^ PetStore3.java:7: cannot find symbol symbol : variable Fish location: class PetStore3 String fishColor = Fish.color; ^ PetStore3.java:12: cannot find symbol symbol : variable Fish location: class PetStore3 Fish.skill(); ^ 5 errors |
| c:sourcewater | .;c:source; | c: | OK |
| c:sourcewater | .; | c:source | OK |
| c:sourcewater | .;c:; | c:source | OK |
| c:sourcewater | .;c:source; | c:source | OK |
| c:sourcewater | .;any path; | c:source | OK（主要是classpath設.的關係） |
| c:sourcejavawater | .; | c: | package water does not exit; |
| c:sourcejavawater | .; | c:source | package water does not exit; |
| c:sourcejavawater | .; | c:sourcejava | OK |
| d:sourcejavawater | .; | d:sourcejava | package water does not exit; |
噫！”.”不是依照目前的目錄去找package的class嗎？可是放在d:時，好像就不是這樣了，看來java的編譯規則的classpath的”.”是指針對c:講的，我終於有點恍然大悟，但是很多課本及網頁都說是依照目前的目錄去搜尋class的path，看來是有很大的爭議的，不過有這個測試之後，感覺釐清了很多觀念！