From Gossip@caterpillar

Java Gossip: ネΘン

眤ㄏノClassnewInstance()よ猭ㄓ龟ㄒてンㄒ 
Class c = Class.forName(args[0]);
Object obj = c.newInstance();
 

狦更摸﹚竡Τ礚把计篶ㄧΑ玥ㄏノ硂贺よΑㄓ篶ぃ﹚﹍把计ン狦眤璶笆篈更のネΘン﹚把计玥璶﹚把计摸眔ConstructorンㄏノConstructornewInstance()﹚把计

ㄒㄓ弧и﹚竡Student摸
  • Student.java 
package onlyfun.caterpillar;

public class Student  {
    private String name;
    private int score; 

    public Student() { 
        name = "N/A"; 
    } 

    public Student(String name, int score) { 
        this.name = name; 
        this.score = score; 
    } 

    public void setName(String name) {
        this.name = name;
    }
    
    public void setScore(int score) {
        this.score = score;
    }

    public String getName() { 
        return name; 
    } 

    public int getScore() { 
        return score; 
    } 

    public String toString() {
        return name + " " + score;
    }
}

礛笆篈更よΑㄓ笆篈ネΘン
  • NewInstanceDemo.java 
package onlyfun.caterpillar;
 
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
 
public class NewInstanceDemo {
    public static void main(String[] args) {
        Class c = null;
        
        try {
            c = Class.forName(args[0]);
            
            // ﹚把计篈
            Class[] params = new Class[2];
            params[0] = String.class;
            params[1] = Integer.TYPE;
            
            Constructor constructor = 
                             c.getConstructor(params);
            
            // ﹚把计ず甧
            Object[] paramObjs = new Object[2];
            paramObjs[0] = "caterpillar";
            paramObjs[1] = new Integer(90);
            
            // 龟ㄒて
            Object obj = constructor.newInstance(paramObjs);
            System.out.println(obj);
 
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SecurityException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }
}

磅︽ㄒ
java onlyfun.caterpillar.NewInstanceDemo onlyfun.caterpillar.Student
caterpillar 90