cannot find symbol on declaration of array Class[]

Question

I'm trying to call method from .jar

But when I want to declare array of params for getDeclaredMethod I've got an error "cannot find symbol" on

Class[] params = new Class[]{ String };
                              ^

Whole method

 public void CallCloseWindow(String title){
        //export dll
        InputStream in = staticapi.class.getResourceAsStream("CloseWindow.dll"); 
        File fileOut = new File(System.getProperty("C:\\Java\\CloseWindow.dll")); 
        OutputStream out = new FileOutputStream(fileOut); 
        int c;
        while ((c = in.read()) != -1) { 
            out.write(c);
        }
        in.close(); 
        out.close(); 
        //call from jar class
        Class[] params = new Class[]{ String };
        Object[] parms = new Object[] { new String(title) };
        URL url=new URL("jar:file:/callapi.jar/");
        URLClassLoader ucl = new URLClassLoader(new URL[] { url });
        Class obj = Class.forName("callapi.callapi", true, ucl);
        Method m = obj.getDeclaredMethod("CloseWindow",params);
        Object instance = obj.newInstance();
        Object result = m.invoke(instance,parms);
    }

What's the problem?String.TYPE doesn't work either

Federico Vera · Accepted Answer · 2012-04-01 19:08:10Z

4

Try with Class[] params = new Class[]{ String.class };

answered Apr 1, 2012 at 19:08

Federico Vera

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5 Comments

Caffeinated Over a year ago

This is Java? What kind of construct is that - new Class[]{ String.class }

Federico Vera Over a year ago

Yes it's Java, you are constructing a Class array with only one element (the String.class).

NPE Over a year ago

@Adel: This is perfectly standard Java (but the bit you've quoted is incomplete and makes no sense without the new).

Caffeinated Over a year ago

@Fido - Thank You Very Much, that's pretty powerful.

Артём Царионов Over a year ago

I was waiting for several minutes but then forgot about it.

Alex Stybaev · Accepted Answer · 2012-04-01 19:09:06Z

1

try:

Class[] params = new Class[]{ String.class };

answered Apr 1, 2012 at 19:09

Alex Stybaev

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Comments

aioobe · Accepted Answer · 2012-04-01 19:15:20Z

1

As others have pointed out, you just missed the .class. No need to call new when initializing an array on declaration though:

Class[] params = { String.class };

should do fine. (It is only if you reinitialize the array later on, or if you for instance create an anonymous array you would need new.)

In fact, you don't need to create the params array at all. Since Class.getDeclaredMethods is a vararg method you could just do

Method m = obj.getDeclaredMethod("CloseWindow", String.class);
                                                \__________/
                                                     |
        this will be transformed to a Class[] on the fly by the constructor

answered Apr 1, 2012 at 19:15

aioobe

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