Cannot find symbol : default access interfaces(declared in different src file) implemented on a public class java using `javac` command

Question

This is a really novice question but I am not able to implement any default-access interface from the first source file('F:/Java_Practice/src/listpage1/interfaceTest/InterfaceCan.java;`) on the public class in the second source file(F:/Java_Practice/src/listpage1/interfaceTest/InterfaceCan1.java;). Please throw light on this. Thankyou!

/* Source file name listpage1.interfaceTest.InterfaceCan1.java */

package listpage1.interfaceTest;

import static java.lang.System.out;

public interface InterfaceCan1
    {
        int iCan_var = 2;
        void iCanMethod();
    }

class PackageInfo
{
    void packInfo()
    {
        out.println("This package is meant to contain all the interfaces used for testing the behavior of interfaces.");
    }
}
interface I1
{
    int i1_var = 1;
    void i1Method();
}

interface I1x extends I1
{
    int i1x_var = 10;
    void i1xMethod();
}

interface I2x extends InterfaceCan1
{
    int i2x_var = 20;
    void i3xMethod();
}

interface I3
{
    int I3 = 3;
    void i3Method();
}

//Another source file: listpage1.interfaceTest.InterfaceTest.java

package listpage1.interfaceTest;

import static java.lang.System.out;


public class InterfaceTest implements I1//This line is throwing error
{
    public void i1Method()
    {
        out.println("Inside the method InterfaceTest.i1Method()");
    }
    public static void main(String[] s)
    {
        TestInterface1 ob1 = new TestInterface1();
        out.println(ob1.i_var);
        ob1.iMethod();
        out.println(ob1.iCan_var);
        ob1.iCanMethod();
    }
}

interface I
{
    int i_var = 0;
    void iMethod();
}

class TestInterface1 implements I, InterfaceCan1, I1
{
    public void iMethod()
    {
        out.println("Inside the method TestInterface1.iMethod().");
    }

    public void iCanMethod()
    {
        out.println("Inside the method TestInterface1.iCanMethod()");
    }
    public void i1Method()
    {
        out.println("Inside the method TestInterface1.i1Method()");
    }
}

class InterfaceTest2 implements I1
{
    public void i1Method()
    {
        out.println("Inside the method TestInterface1.i1Method()");
    }
}

Compilation Error:
listpage1\interfaceTest\InterfaceTest.java:6: error: cannot find symbol
public class InterfaceTest implements I1
                                      ^
  symbol: class I1
1 error

Answer 1

Thanks a lot for help in the comments. I finally figured out why I was not abel to compile the program. In order for the Interface to be detected while compiling using -d option (by which the .class files are placed in a different directory)

For example: My Dir structure used: F:/Java_Practice/src This held all the .java files. I was compiling all the files from this folder and placing the resulting .class files in F:/Java_Practice/class folder by using the following command: "F:\Java_Practice\src>javac -d F:/Java_Practice/class listpage1/interfaceTest/InterfaceTest.java"(Refer to code in question)

The .class of that interface and all other classes which got placed in another directory(In this case:'F:/Java_Practice/class'). Now that directory needs to be specified while compiling the .java file using the -classpath option like so:

F:\Java_Practice\src>javac -d F:/Java_Practice/class -classpath .;F:/Java_Practice/class listpage1/interfaceTest/InterfaceTest.java

Interestingly If you miss the -classpath option while compiling you will still be able to access all the public classes and public interfaces! However to access default-access classes and interfaces you will have to include -classpath in javac command

Please go through this link for more details on setting classpath: http://docs.oracle.com/javase/8/docs/technotes/tools/windows/classpath.html