36 lines
1.1 KiB
Java
36 lines
1.1 KiB
Java
// generics/UnboundedWildcards2.java
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// (c)2020 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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import java.util.*;
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public class UnboundedWildcards2 {
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static Map map1;
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static Map<?,?> map2;
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static Map<String,?> map3;
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static void assign1(Map map) { map1 = map; }
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static void assign2(Map<?,?> map) { map2 = map; }
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static void assign3(Map<String,?> map) { map3 = map; }
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public static void main(String[] args) {
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assign1(new HashMap());
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assign2(new HashMap());
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//- assign3(new HashMap());
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// warning: [unchecked] unchecked method invocation:
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// method assign3 in class UnboundedWildcards2
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// is applied to given types
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// assign3(new HashMap());
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// ^
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// required: Map<String,?>
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// found: HashMap
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// warning: [unchecked] unchecked conversion
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// assign3(new HashMap());
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// ^
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// required: Map<String,?>
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// found: HashMap
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// 2 warnings
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assign1(new HashMap<>());
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assign2(new HashMap<>());
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assign3(new HashMap<>());
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}
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}
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