package org.aliangliang.tanetroamer;

import java.util.concurrent.Callable;

public class Callback implements Callable<String> {

    public String call(String param) throws Exception {
        return param;
    }

    @Override
    public String call() throws Exception {
        return null;
    }

}

@@ -35,269 +35,89 @@
 r;%0A%0A
-import java.util.concurrent.Callable;%0A%0Apublic class Callback implements Callable%3CString%3E %7B%0A%0A    public String call(String param) throws Exception %7B%0A        return param;%0A    %7D%0A%0A    @Override%0A    public String call() throws Exception %7B%0A        return null;%0A    %7D%0A
+public interface Callback %7B%0A    public String call(String param) throws Exception;
 %0A%7D%0A

Use interface