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public class ListInspectorExample {
  public static void inspect(List<List<String>> l) {
    for (List<String> list : l) {
      for (String s : list) {      // ClassCastException on 42
        System.out.println(s);
      }
    }
  }

  public static void main(String[] args) {
    List<String> s = Arrays.asList("foo");
    List i = Arrays.asList(42);    // warning about raw types
    List<List<String>> l = new ArrayList<List<String>>();
    l.add(s);
    l.add(i);                      // warning about unchecked convertion
    inspect(l);
  }
}

h2. 

Noncompliant

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Code

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Example

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(Array

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of

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lists)

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The

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problem

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persists

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if

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the

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function

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paramter

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is

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replaced

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with

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an

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array

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of

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lists

{:=|

Code Block
bgColor	#ffcccc	lang java
public class ListInspectorExample {=java} public static void inspect(List<String>[] l) { for (List<String> list : l) { for (String s : list) { // ClassCastException on 42 System.out.println(s); } } } public static void main(String[] args) { List<String> s = Arrays.asList("foo"); List i = Arrays.asList(42); // warning about raw types inspect(new List[] {s, i}); // warning about unchecked convertion } } h2. Noncompliant Code Example

Noncompliant Code Example (Variadic

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Arguments)

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The

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problem

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persists

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if

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the

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function

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parameter

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is

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changed

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to

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a

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variadic

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argument

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of

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List<String>

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.

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During

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type

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erasure,

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the

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compiler

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translates

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this

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to

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a

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single

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array

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of

...

objects.

{:=|

Code Block
bgColor	#ffcccc	lang java
public =java} class ListInspectorListInspectorExample { public static void inspect(List<String>... l) { for (List<String> list : l) { for (String s : list) { // ClassCastException on 42 System.out.println(s); } } } public static void main(String[] args) { List<String> s = Arrays.asList("foo"); List i = Arrays.asList(42); // warning about raw types inspect( s, i); // warning about variadic generic parameter } }

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Code Block
bgColor #ccccff lang java
public class ListInspectorListInspectorExample { public static void inspect(List<String>... l) { for (List<String> list : l) { for (String s : list) { // ClassCastException on 42 System.out.println(s); } } } public static void main(String[] args) { List<String> s = Arrays.asList("foo"); List<Integer> i = Arrays.asList(42); inspect( s, i); // improper argument types compiler error } }

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