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[英]How to get value from HashMap depending on key name, while we are passing custom class objects as key and value
[英]Passing class in Hashmap and how to get the value using key
我正在嘗試將 class 作為 hashmap 中的值傳遞。我需要使用特定鍵獲取類(值)並為檢索到的 class 實例化 object。但是為了創建 object,我需要傳遞參數。
當我從另一個傳遞鍵值的 class 調用 getExpo 方法時,我的流程就到這里了。 using the key value, i need to get the correct class and using that class need to instantiate the object and need to return the object. Inorder to create object, i need to pass the arguments since the class doesnot have default constructors.
此過程的目的是在將來,我需要添加另一個鍵,對值,我不應該做任何更改.......所有 class 的實現都是相同的,即創建 object
我的 class 在這里
public class ExampleFactory {
static {
HashMap<String,Class<?>> hmap = new HashMap<String,Class<?>>();
hmap.put("jxpath", JXPathExpression.class);
hmap.put("spel", SpelExpression.class);
}
public Predicate getExpo(String key,String expression) {
// Need to get the class using key value and instantiate the object for the class
// but i need to pass parameters in order to create the object.something like this
//JXPathExpression object = new JXPathExpression(expression);
return null;
}
}
嘗試
Class aClass = hmap.get(key);
Constructor constructor = aClass.getConstructor(new Class[]{String.class});
return (Predicate) constructor.newInstance(expression);
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