Java: How can I access a class's field by a name stored in a variable?

问题

How can I set or get a field in a class whose name is dynamic and stored in a string variable?

public class Test {

    public String a1;
    public String a2;  

    public Test(String key) {
        this.key = 'found';  <--- error
    } 

}

回答1:

You have to use reflection:

Use Class.getField() to get a Field reference. If it's not public you'll need to call Class.getDeclaredField() instead
Use AccessibleObject.setAccessible to gain access to the field if it's not public
Use Field.set() to set the value, or one of the similarly-named methods if it's a primitive

Here's an example which deals with the simple case of a public field. A nicer alternative would be to use properties, if possible.

import java.lang.reflect.Field;

class DataObject
{
    // I don't like public fields; this is *solely*
    // to make it easier to demonstrate
    public String foo;
}

public class Test
{
    public static void main(String[] args)
        // Declaring that a method throws Exception is
        // likewise usually a bad idea; consider the
        // various failure cases carefully
        throws Exception
    {
        Field field = DataObject.class.getField("foo");
        DataObject o = new DataObject();
        field.set(o, "new value");
        System.out.println(o.foo);
    }
}

回答2:

Class<?> actualClass=actual.getClass();

Field f=actualClass.getDeclaredField("name");

The above code would suffice .

object.class.getField("foo");

Unfortunately the above code didn't work for me , since the class had empty field array.

来源：https://stackoverflow.com/questions/2127197/java-how-can-i-access-a-classs-field-by-a-name-stored-in-a-variable

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