java - 如何按照插入 HashMap 的顺序打印 HashMap 值

Question

我有一个 HashMap，其中包含字符串作为键和值，

HashMap dataSet = new HashMap();

dataSet.put("A1", "Aania");
dataSet.put("X1", "Abatha");
dataSet.put("C1", "Acathan");
dataSet.put("S1", "Adreenas");

我想按照插入 HashMap 的顺序打印它，所以输出应该是这样的，

A1, Aania
X1, Abatha
C1, Acathan
S1, Adreenas  

谁能告诉我该怎么做？

Answer 1

您可以使用 LinkedHashMap相反，这将保留插入顺序。您无法使用标准 HashMap 完成您所要求的操作。

This implementation differs from HashMap in that it maintains a doubly-linked list running through all of its entries. This linked list defines the iteration ordering, which is normally the order in which keys were inserted into the map (insertion-order).

因此代码的第一行将变为:

Map dataSet = new LinkedHashMap();

您可能还想添加泛型作为一种好的做法:

Map<String, String> dataSet = new LinkedHashMap<String, String>();