理工女孩

偶然看到一個結構TreeMap，所以將它拿來將HashMap來做區別

HashMap再存入key和value的時候時隨機存入的，要拿取的時候是利用key來將相對應的value拿出來，如果想要在Map中新增或刪除，HashMap比較好用

TreeMap會自動將存入的key做排序，若是想要存入Map並有排序的話，TreeMap較好用

Kotlin Example

Step 1:

先新增兩種類型

val hashmap = HashMap<String,String>()
val treemap = TreeMap<String,String>()

Step 2:

在hashmap和treemap中我都新增相同的東西

hashmap.put("A","1")
hashmap.put("D","4")
hashmap.put("C","3")
hashmap.put("B","2")

treemap.put("A","1")
treemap.put("D","4")
treemap.put("C","3")
treemap.put("B","2")

Step 3:

再把它印出來驗證有沒有排序

for((key, value) in hashmap){
    Log.d(TAG,"Hash Map[$key] = $value")
}
Log.d(TAG,"Hash Map:"+hashmap)

for((key, value) in treemap){
    Log.d(TAG,"Tree Map[$key] = $value")
}
Log.d(TAG,"Tree Map:"+treemap)

Strp 4:

結果會是

可以很明顯地看到TreeMap是依照順序排好，則HashMap就是依照當初的順序存放的

JAVA Example

因為是一樣的東西，只是換成JAVA所以我就只有把程式碼貼上來

Step 1:

private HashMap<String,String> hashMap = new HashMap<>();
private TreeMap<String,String> treeMap = new TreeMap<>();

Step 2:

hashMap.put("A","1");
hashMap.put("D","4");
hashMap.put("C","3");
hashMap.put("B","2");

treeMap.put("A","1");
treeMap.put("D","4");
treeMap.put("C","3");
treeMap.put("B","2");

Step 3:

for (String name:hashMap.keySet()) {
    Log.d(TAG,"Hash Map key:"+name);
}
Log.d(TAG,"Hash Map:"+hashMap);

for (String name:treeMap.keySet()) {
    Log.d(TAG,"Tree Map key:"+name);
}
Log.d(TAG,"Tree Map:"+treeMap);

Step 4: