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Java Program to convert a Map to a read only map
Let’s say the following is our Map −
Map<String, String>map = new HashMap<String,String>();
map.put("1","A");
map.put("2","B");
map.put("3","C");Make it read-only using the unmodifiableMap() method −
map = Collections.unmodifiableMap(map);
Example
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
public class Demo {
public static void main(String[] argv) throws Exception {
Map<String, String>map = new HashMap<String,String>();
map.put("1","A");
map.put("2","B");
map.put("3","C");
// making it read-only
map = Collections.unmodifiableMap(map);
try {
map.put("4","D");
map.put("5","E");
map.put("6","F");
} catch (UnsupportedOperationException e) {
System.out.println(e.getMessage());
}
}
}Output
null
Updated on: 30-Jul-2019
169 Views
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