java - 根据类设置和获取字段

Question

我有 2 个包:Presentation，其中主类带有类Methods，
以及一个包含实体的包:Entity1 和 Entity2。
Entity1 有 private StringEntity1var; 和
Entity2 有私有(private)整数entity2var;

类看起来像这样:

public class Entity1 {
private String entity1var;

/**
 * @return the entity1var
 */
public String getEntity1String() {
    return entity1var;
}

/**
 * @param entity1String the entity1var to set
 */
public void setEntity1String(String entity1String) {
    this.entity1var = entity1String;
}
}

并且:

public class Entity2 {
private Integer entity2var;

/**
 * @return the entity2var
 */
public Integer getEntity2Integer() {
    return entity2var;
}

/**
 * @param entity2Field the entity2var to set
 */
public void setEntity2Integer(Integer entity2Field) {
    this.entity2var = entity2Field;
}
}

主类:

public class Main {
public static void main(String ARGS[]){
    Methods _methods = new Methods();
    _methods.doSomething("Entity1");
    _methods.doSomething("Entity2");
}
}

方法类:

public class Methods {
public void doSomething(String newClass){
    try {
        Class _class =  Class.forName("Entities."+newClass);
        //How can I set the variable on each class 
        //and get the value after 

        //Something similar to this:
        //_class.setEntity1String("Im new");
        //System.out.println(_class.getEntity1String); -> Result: Im new

        //_class.setEntity2Integer(777);
        //System.out.println(_class.getEntity2Integer); -> Result: 777


    } catch (ClassNotFoundException ex) {
        Logger.getLogger(Methods.class.getName()).log(Level.SEVERE, null,         ex);
    }
}
}

我尝试过这样的事情:

    Class newClass = Class.forName("Entities."+className);
    Method newMethod = newClass.getDeclaredMethod("getEntity1String");
    Object newValue = newMethod.invoke(newClass.newInstance());
    System.out.println(newValue);

如果我给它一个值，它确实会显示变量中的值 private StringEntity1var = "Something new" 但如何在不使用经典实例化的情况下更改该值？我想避免这种情况，因为我不知道我将收到什么类(class):

Entity1 entity = new Entity1();
entity.setEntity1String("Im also new");

解决方案(感谢immibis):

        Class _class = Class.forName("Entities." + newClass);
        Object _classInstance = (Object) _class.newInstance();
        Method _newMethod = _class.getDeclaredMethod("setEntity1String", String.class);
        _newMethod.invoke(_classInstance, "New String");

        Method _method = _class.getDeclaredMethod("getEntity1String");
        Object _methodValue = _method.invoke(_classInstance);
        System.out.println(_methodValue);

Answer 1

您使用反射调用了 getEntity1String，如下所示:

Class newClass = Class.forName("Entities."+className);
Method newMethod = newClass.getDeclaredMethod("getEntity1String");
Object newValue = newMethod.invoke(theInstanceYouWantToCallTheMethodOn);

您可以使用反射调用 setEntity1String，以同样的方式，如下所示:

Class newClass = Class.forName("Entities."+className);
Method newMethod = newClass.getDeclaredMethod("setEntity1String", String.class); // argument types need to be passed to getDeclaredMethod
newMethod.invoke(theInstanceYouWantToCallTheMethodOn, newValue); // need to pass the actual argument values now; also we don't care about the return value so it's not assigned to anything