可存重复键的HashMap

package com.ts.utils;
import java.util.*;

import java.util.function.BiConsumer;
public class SortMap<K, V> {

public TreeMap<K, Object> sortContain = new TreeMap<K, Object>();
public void put(K key, V value) {
    if (sortContain.containsKey(key)) {
        Object nowValue = sortContain.get(key);
        if (nowValue instanceof ArrayList) {
            ((ArrayList) nowValue).add(value);
        } else if (nowValue instanceof String) {
            ArrayList&lt;V&gt; temp = new ArrayList&lt;&gt;();
            temp.add((V) nowValue);
            temp.add(value);
            sortContain.put(key, temp);
        }
    } else {
        sortContain.put(key, value);
    }
}

//在jsp里用 action里的东西会变

public void forEach(BiConsumer<K, V> action) {

Objects.requireNonNull(action);

sortContain.forEach((key, value) -> {

if (value instanceof ArrayList) {

((ArrayList) value).forEach((value1) -> {

action.accept(key, (V) value1);

});

} else if (value instanceof String)

action.accept(key, (V) value);

});

}
public Map.Entry&lt;K, Object&gt; firstEntry() {
    return sortContain.firstEntry();
}

public Map.Entry&lt;K, Object&gt; higherEntry(K key) {
    return sortContain.higherEntry(key);
}

public void clear() {
    sortContain.clear();
}

}