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Within my MainActivity.java I am trying to open a file according to the code given here. But when running the code

public class MainActivity extends AppCompatActivity {

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

        final Button button = (Button) findViewById(R.id.btn1);
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Toast.makeText(getBaseContext(), "YOUR TEXT HERE", Toast.LENGTH_LONG).show();
                // Perform action on click

                FileInputStream fis = getBaseContext().openFileInput("hello.txt", Context.MODE_PRIVATE);
                InputStreamReader isr = new InputStreamReader(fis);
                BufferedReader bufferedReader = new BufferedReader(isr);
                StringBuilder sb = new StringBuilder();
                String line;
                while ((line = bufferedReader.readLine()) != null) {
                    sb.append(line);
                }
            }
        });

    }
}

I get the following error: 

Error:(27, 55) error: method openFileInput in class Context cannot be applied to given types;
required: String
found: String,int
reason: actual and formal argument lists differ in length

I am not even able to understand what the error means. What 'argument list' is the message referring to?

Community
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Alex
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  • pass only file name instead of filename and mode in `FileInputStream`. Before using someones code from stackoverflow try to read comments as well – jack jay Jan 12 '17 at 20:11
  • That seems to work. So I guess the example code is wrong, for some reasons. – Alex Jan 12 '17 at 20:12
  • Don't use `getBaseContext()` unless you know what you're doing with it, and have an explicit reason to. Just call `openFileInput()` directly on the `Activity`, which is a `Context`. – Mike M. Jan 12 '17 at 20:12
  • Even better. I have no idea what `getBaseContext()` does ... – Alex Jan 12 '17 at 20:13
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    And yeah, that example is wrong. `openFileInput()` only takes the `String` argument. – Mike M. Jan 12 '17 at 20:16

2 Answers2

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As mentioned by @MuhammadKashifArif:

Instead of this

FileInputStream fis = getBaseContext().openFileInput("hello.txt",Context.MODE_PRIVATE);

use this

FileInputStream fis = openFileInput("hello.txt", MODE_PRIVATE);

It doesn't matter.

Context is context, and getBase context is still the same context as everything else, calling getBaseContext doesn't change the type of context compared to using this in an activity. There is no difference between accessing MODE_PRIVATE statically and using import static

I am not sure when exactly this changed (and I am not going to look through every version of android to check either), but it is openFileOutput that takes two arguments, a String an an Integer.

openFileInput now only takes one argument. So:

FileInputStream fis = /*Some context here if you are outside an activity.*/openFileInput("hello.txt");

And to load:

FileOutputStream fos = /*some context if outside activity.*/openFileOutput("hello.txt", Context.MODE_PRIVATE);

And I would once again like to clear up the fact that it doesn't make a difference whether or not you call getBaseContext, getApplicationContext, or call this/SomeActivity.this inside an activity. The context class itself doesn't change, the fields are the same. And writing MODE_PRIVATE without Context. in front of it is called a static import. The only difference between Context.MODE_PRIVATE and the static import MODE_PRIVATE is only you don't have to type those characters. The method doesn't exist no matter how you call it

As for the compile error, it basically says you are supplying more arguments than the method requires. You should also see a red warning over the call to the method as well, but what you see is the compile error as you tried to compile the build while there is a call to an unknown method.

Zoe
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0

As @LunarWatcher said the openFileInput takes 1 parameter.So,

Instead of this

FileInputStream fis = getBaseContext().openFileInput("hello.txt",Context.MODE_PRIVATE);

use this

FileInputStream fis = openFileInput("hello.txt");
Muhammad Kashif Arif
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