Close

Java Collections - Collections.checkedSortedMap() Examples

Java Collections Java Java API 

PreviousNext

Class:

java.util.Collections

java.lang.Objectjava.lang.Objectjava.util.Collectionsjava.util.CollectionsLogicBig

Method:

public static <K,V> SortedMap<K,V> checkedSortedMap(SortedMap<K,V> m,
                                                    Class<K> keyType,
                                                    Class<V> valueType)

Returns a dynamically typesafe view of the specified SortedMap.


Examples


package com.logicbig.example.collections;

import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;

public class CheckedSortedMapExample {

    public static void main(String... args) {
        SortedMap<Integer, String> map = new TreeMap<>();
        map.put(1, "one");
        System.out.println(map);

        Map map2 = map;
        map2.put(2, 3);
        System.out.println(map2);
    }
}

Output

{1=one}
{1=one, 2=3}




Using checkedSortedMap: 

package com.logicbig.example.collections;

import java.util.Collections;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;

public class CheckedSortedMapExample2 {

    public static void main(String... args) {
        SortedMap<Integer, String> map = new TreeMap<>();
        map = Collections.checkedSortedMap(map, Integer.class, String.class);
        map.put(1, "one");
        System.out.println(map);

        Map map2 = map;
        map2.put(2, 3);
        System.out.println(map2);
    }
}

Output

Caused by: java.lang.ClassCastException: Attempt to insert class java.lang.Integer value into map with value type class java.lang.String
	at java.util.Collections$CheckedMap.typeCheck(Collections.java:3577)
	at java.util.Collections$CheckedMap.put(Collections.java:3620)
	at com.logicbig.example.collections.CheckedSortedMapExample2.main(CheckedSortedMapExample2.java:23)
	... 6 more

See Also