更新 java 地图条目
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Updating a java map entry
提问by jrharshath
I'm facing a problem that seems to have no straighforward solution.
我面临一个似乎没有直接解决方案的问题。
I'm using java.util.Map, and I want to update the value in a Key-Value pair.
我正在使用java.util.Map，并且我想更新键值对中的值。
Right now, I'm doing it lik this:
现在，我正在这样做：
private Map<String,int> table = new HashMap<String,int>();
public void update(String key, int val) {
if( !table.containsKey(key) ) return;
Entry<String,int> entry;
for( entry : table.entrySet() ) {
if( entry.getKey().equals(key) ) {
entry.setValue(val);
break;
}
}
}
So is there any method so that I can get the required Entryobject without having to iterate through the entire Map? Or is there some way to update the entry's value in place? Some method in Maplike setValue(String key, int val)?
那么有没有什么方法可以让我获得所需的Entry对象而不必遍历整个Map？或者有什么方法可以更新条目的值？一些方法在Map喜欢setValue(String key, int val)吗？
jrh
jrh
采纳答案by skaffman
Use
用
table.put(key, val);
to add a new key/value pair or overwrite an existing key's value.
添加新的键/值对或覆盖现有键的值。
From the Javadocs:
来自 Javadocs：
V put(K key, V value): Associates the specified value with the specified key in this map (optional operation). If the map previously contained a mapping for the key, the old value is replaced by the specified value. (A map m is said to contain a mapping for a key k if and only if m.containsKey(k) would return true.)
V put(K key, V value)：将指定值与此映射中的指定键关联（可选操作）。如果映射先前包含键的映射，则旧值将替换为指定值。（当且仅当 m.containsKey(k) 返回 true 时，才称映射 m 包含键 k 的映射。）
回答by mkoeller
回答by Priyank
If key is present table.put(key, val)will just overwrite the value else it'll create a new entry. Poof! and you are done. :)
如果存在键，table.put(key, val)则只会覆盖该值，否则会创建一个新条目。噗！你就完成了。:)
you can get the value from a map by using key is table.get(key);That's about it
您可以通过使用键从地图中获取值，就是table.get(key);这样
