java 通用类型,Java接口通用类型

Never used Java before and trying to implement an interface in a class:

Interface:

public interface TestInterface {

public void doSomething(E elem);

}

Class:

public class TestClass implements TestInterface {

public static void main() {

// ...

}

public void doSomething(E elem) {

// ...

}

}

When I run the javac compiler. I get these errors:

TestClass.java:5: cannot find symbol

symbol: class E

public class TestClass implements TestInterface {

^

TestClass.java:11: cannot find symbol

symbol : class E

location: class TestClass

public void doSomething(E elem) {

^

If I replace all the "E"'s with i.e. "String", it will work, but I want it to use generic types. How do I do this?

解决方案

When creating TestClass you need to pass what is E, something like below

public class TestClass implements TestInterface {

public static void main() {

// ...

}

public void doSomething(String elem) {

// ...

}

}

or you need to make TestClass as generic

public class TestClass implements TestInterface {

public static void main() {

// ...

}

public void doSomething(E elem) {

// ...

}

}