Calling a method from library (jar)

Question

I'm trying to understand library usage in Android. So I created a very simple library and import it in my project. I want to call the method cubeOf() from MyOperations.jar (library file). There is no building errors but the application is stopping unexpectedly when I runned.

MainActivity.java class (in MyApplication):

package com.sam.myapplication;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.widget.TextView;
import com.sam.mylibrary.MyOperations;

public class MainActivity extends Activity {

    TextView tv1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        tv1 = (TextView) findViewById(R.id.textView1);
        MyOperations op = new MyOperations();
        int a = op.cubeOf(8); // Just a random number
        tv1.setText(a);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
}

MyOperations.java class (in MyLibrary):

package com.sam.mylibrary;

public class MyOperations {
    public static void main(String[] arg) {

    }
    public static int cubeOf(int i) {
        int c = i*i*i;
        return c;
    }
}

SOLVED!

Thanks for replies, I solved the issue through this article.

cubeOf being a static method should be accessed in a static way: MyOperations.cubeOf(). — Goran Horia Mihail, Dec 14 '13 at 20:48
If the app's crashing, you should have a stack trace of some kind in your console; that should help you find the problem—if it doesn't, post it here as more information. — Josh, Dec 14 '13 at 21:25
@SpacePope Thanks for advice I added my log errors to the post. — smtnkc, Dec 14 '13 at 22:41

score 0 · Answer 1 · answered Dec 14 '13 at 20:47

0

Change

    tv1.setText(a);

with

 tv1.setText(String.valueOf(a));

in your case you are using a as index for R.string, and if it does not exist, ResourceNotFoundException will be thrown

answered Dec 14 '13 at 20:47

Blackbelt

156,034
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Thanks but nothing changed. – smtnkc Dec 14 '13 at 21:09

score 0 · Answer 2 · edited Jun 20 '20 at 09:12

0

You are not mentioning the reason for your application to crash. I believe there might be 2 problems:

1 adding to blackbelt answer above:

you might simply use:

put setText(""+a)

So there isn't confusion about 'a' being used as numeric vs. string

2 You may have a build path issue.

Look at this answer:

How can I use external JARs in an Android project?

If you have a pretty recent version of Eclipse/ADT the folder should be called 'libs' else the folder was called 'lib' ( Eclipse/ADT TBD )

Also, the "Java Build Path" -> "Order And Export" make sure you are checking on the external library especially if from a different package.

edited Jun 20 '20 at 09:12

Community

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1

answered Dec 14 '13 at 21:00

Rastikan

517
5
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I have already built the path, and yes i'm using a recent version. – smtnkc Dec 14 '13 at 22:39
Did you checked marked the library as export in the "Order And Export" tab ? Actually, are using a reference project or a compiled .jar version? Did you exported classes from the library project? – Rastikan Dec 14 '13 at 22:45
Do you have a s ky pe ac c o unt? I can offer a few minutes of support. – Rastikan Dec 14 '13 at 22:52

score 0 · Answer 3 · answered Dec 14 '13 at 21:22

0

So just to confirm earlier responses, you tried both changes in onCreate? That is,

    int a = MyOperations.cubeOf(8); // Just a random number
    tv1.setText(String.valueOf(a));

call static methods statically (don't even new a MyOperations)
pass a string to setText

answered Dec 14 '13 at 21:22

Rob Starling

3,868
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Yes, i did both of them. – smtnkc Dec 14 '13 at 22:19

Calling a method from library (jar)

SOLVED!

3 Answers3

1 adding to blackbelt answer above:

2 You may have a build path issue.