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UnboundedWildcards2.java
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35 lines (34 loc) · 1.14 KB
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// generics/UnboundedWildcards2.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
import java.util.*;
public class UnboundedWildcards2 {
static Map map1;
static Map<?,?> map2;
static Map<String,?> map3;
static void assign1(Map map) { map1 = map; }
static void assign2(Map<?,?> map) { map2 = map; }
static void assign3(Map<String,?> map) { map3 = map; }
public static void main(String[] args) {
assign1(new HashMap());
assign2(new HashMap());
//- assign3(new HashMap());
// warning: [unchecked] unchecked method invocation:
// method assign3 in class UnboundedWildcards2
// is applied to given types
// assign3(new HashMap());
// ^
// required: Map<String,?>
// found: HashMap
// warning: [unchecked] unchecked conversion
// assign3(new HashMap());
// ^
// required: Map<String,?>
// found: HashMap
// 2 warnings
assign1(new HashMap<>());
assign2(new HashMap<>());
assign3(new HashMap<>());
}
}