如何在同一个包中访问Java类

Question

I have two java files (A.java + B.java) in src/com/example

A.java

package com.example;

public class A {
    public void sayHello(){
        System.out.println("Hello");
    }
}

B.java

package com.example;

public class B{
    public static void main(String... args) {
        A a = new A();
        a.sayHello();
    }
}

If I cd to one level above src and type javac -d classes src/com/example/B.java

I get an error saying cannot find symbol A?

Answer 1

javac doesn't know where to find source class you have to specify it with -sourcepath option.

See:

C:\example>mkdir src
C:\example>type > src/
C:\example>mkdir src\com\example
C:\example>more > src\com\example\A.java
package com.example;
public class A {
}
^C
C:\example>more > src\com\example\B.java
package com.example;
public class B {
    A a;
}
^C
C:\example>javac -d
C:\example>mkdir classes
C:\example>javac -d classes src\com\example\B.java
src\com\example\B.java:3: cannot find symbol
symbol  : class A
location: class com.example.B
        A a;
        ^
1 error
C:\example>javac -d classes -sourcepath src src\com\example\B.java
C:\example>

Answer 2

That's because Java doesn't know where to find the source of the other file. You need to either cd into the src directory, or specify the src directory on the -sourcepath .

Answer 3

试试javac -d classes src / com / example / * .java