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POWeird error when using foreach loop in java
 

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  1. POWeird error when using foreach loop in java
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    <p>I am working on a little todolist-program and i'm getting a weird bug that i never had before. I have 4 classes: 1 POJO class that contains the todo-data:</p> <pre><code>public class Todo implements Comparable { private String title; private String task; private boolean done; public Todo(String title, String task) { this.title = title; this.task = task; } public String getTitle() { return title; } public void setTitle(String newTitle) { title = newTitle; } public String getTask() { return task; } public void setTask(String newTask) { task = newTask; } public boolean isDone() { return done; } public void setDone(boolean isDone) { done = isDone; } public int compareTo(Object obj) { Todo todo = (Todo) obj; return getTitle().compareTo(todo.getTitle()); } public String toString() { StringBuilder sb = new StringBuilder(); sb.append("Todo {\n"); sb.append("Title: \""); sb.append(getTitle() + "\";\n"); sb.append("Task: \""); sb.append(getTask() + "\";\n"); sb.append("}"); return sb.toString(); } } </code></pre> <p>Then I have a class that stores and loads my todos:</p> <pre><code>import java.io.BufferedReader; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import java.util.List; import com.google.gson.Gson; import com.google.gson.GsonBuilder; public class ListStorage { Gson gson = new GsonBuilder().setPrettyPrinting().create(); FileWriter writer; BufferedReader reader; public void storeList(List list, String filename) throws IOException { String json = gson.toJson(list); writer = new FileWriter(filename); writer.write(json); writer.close(); } public List loadList(String filename) throws FileNotFoundException { reader = new BufferedReader(new FileReader(filename)); List list = gson.fromJson(reader, List.class); return list; } } </code></pre> <p>Then I have a 'Manager' class that is basically my controller:</p> <pre><code>import java.util.ArrayList; import java.util.Collections; import java.util.List; public class Manager { private List&lt;Todo&gt; todos = new ArrayList&lt;&gt;(); private ListStorage storage = new ListStorage(); public List getTodos() { return todos; } public void setTodos(List newTodos) { todos = newTodos; } public ListStorage getStorage() { return storage; } public void add(String title, String task) { todos.add(new Todo(title, task)); sort(); try { storage.storeList(todos, "todos"); } catch(Exception e) { e.printStackTrace(); } } public void remove(int index) { todos.remove(index); sort(); try { storage.storeList(todos, "todos"); } catch(Exception e) { e.printStackTrace(); } } private void sort() { Collections.sort(todos); } } </code></pre> <p>And finally there is my main-class for testing my code (The bug seems to be here):</p> <pre><code>class CLITodo { public static void main(String[] args) { Manager man = new Manager(); man.add("Hello", "Bye"); man.add("Foo", "Bar"); try { man.setTodos(man.getStorage().loadList("todos")); } catch(Exception e) { } java.util.List&lt;Todo&gt; todos = man.getTodos(); for (Todo t : todos) { System.out.println(t); } } } </code></pre> <p>The error message I get when I leave the <code>&lt;Todo&gt;</code> in CLITodo class is:</p> <pre><code>Exception in thread "main" java.lang.ClassCastException: com.google.gson.internal.LinkedTreeMap cannot be cast to Todo at CLITodo.main(CLITodo.java:13) </code></pre> <p>When I remove <code>&lt;Todo&gt;</code> in CLITodo I get this error:</p> <pre><code>CLITodo.java:13:19: error: incompatible types for (Todo t : todos) { ^ required: Todo found: Object </code></pre> <p>Why does this error occur? My Manager classes getTodos()-Method returns a List of type Todo yet the compiler tells me that it is just an Object (which it is of course but it is a collection as well, which should actually work). This is the first time this error occured and I really can't seem to find what is causing it.</p>
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    1. PO
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    1. USSelim
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    1. COI'm not sure this is your real code. `man.getTodos()` returns a `List`, but you're trying to assign it to a `List<Todo>`...
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      1. USOliver Charlesworth
    2. COChanging the getTodos()-methods type into List<Todo> didn't work either if that was what you mean
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      1. USSelim
 

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