如何从hashmap中找到最高关键值 [英] How to find highest key value from hashmap

问题描述

用最大键值进行迭代，以便它将取代最大字符串值。首先我的代码是

  HashMap< String，String> mapp = new HashMap< String，String>（）; 
 mapp.put（ab，blue）; 
 mapp.put（abc，black）; 
 mapp.put（abcd，pink）; 
 for（Iterator it = alltyp.iterator（）; it.hasNext（）;）{
 String finalstring =（String）it.next（）; 
 
 Iterator it1 = mapp.entrySet（）。iterator（）; （it1.hasNext（））
 {
 Map.Entry pairs =（Map.Entry）it1.next（）; 
 String key_ =（String）pairs.getKey（）; 
 String value_ =（String）pairs.getValue（）; 
 finalstring = finalstring.replaceAll（key_，value_）; 
 
 
 $ / code $ / pre 
 
我想用最大键值进行迭代意味着键值abcd应先迭代，然后abc然后ab。      。如果您想自定义排序，您也可以传递比较器。
 
 $ b 
  HashMap< String，String> mapp = new HashMap< String，String>（）; 
 mapp.put（ab，blue）; 
 mapp.put（abc，black）; 
 mapp.put（abcd，pink）; 
 
 //按字母顺序查找最大按键
字符串maxKey = Collections.max（mapp.keySet（））; 
 
 
比较器< String> strLenCmp = new Comparator< String>（）{
 @Override 
 public int compare（String o1，String o2）{
 return Integer.compare（o1.length（），o2.length（ ））; 
} 
}; 
 
 //通过键长查找最大键值
字符串longKey = Collections.max（mapp.keySet（），strLenCmp）; 
  
 编辑：使用自定义比较器添加示例
 
iterate with max key value so that it will replace max string value. first My code is
HashMap<String, String> mapp=new HashMap<String, String>();
mapp.put("ab","blue");
mapp.put("abc","black");
mapp.put("abcd","pink");
for (Iterator it = alltyp.iterator(); it.hasNext();) {
    String finalstring = (String) it.next();

    Iterator it1=mapp.entrySet().iterator();
    while(it1.hasNext())
    {
        Map.Entry pairs = (Map.Entry) it1.next();
        String key_ = (String) pairs.getKey();
        String value_ = (String) pairs.getValue();
        finalstring = finalstring.replaceAll(key_, value_);      
    }
}
I want to iterate with max key value means key value "abcd" should iterate first then "abc" then "ab".
解决方案
Here is an example using Collections.max().  You can also pass a comparator if you want a custom ordering.
HashMap<String, String> mapp=new HashMap<String, String>();
mapp.put("ab","blue");
mapp.put("abc","black");
mapp.put("abcd","pink");

// find max key alphabetically
String maxKey = Collections.max(mapp.keySet());


Comparator<String> strLenCmp = new Comparator<String>() {
    @Override
    public int compare(String o1, String o2) {
        return Integer.compare(o1.length(), o2.length());
    }
};

// find max key by key length
String longKey = Collections.max(mapp.keySet(), strLenCmp);
Edit: added example with custom Comparator

                        
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