CODEWITHSUNDEEP
javaandroidandroid-intent
Saint Robson
Saint Robson

Reputation: 5525

Making A Toast In An Activity From Different Java Class File

I have 2 .java files : AnswerActivity.java

public class AnswerActivity extends AppCompatActivity {

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

        new JSONTask().execute("https://example.com/api.php");
    }
}

and JSONTask.java 

public class JSONTask extends AsyncTask<String, String, String> {

    @Override
    protected String doInBackground(String... params) {

    //--- some code cut here ---//

    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);

        Intent i = new Intent(this, AnswerActivity.class);
        Toast.makeText(i, result, Toast.LENGTH_LONG).show();
    }
}

my last 2 lines always gives me error :

    Intent i = new Intent(this, AnswerActivity.class);
    Toast.makeText(i, result, Toast.LENGTH_LONG).show();

I want to display the result into AnswerActivity as a Toast. but why I always get this error message? 

Error:(68, 20) error: no suitable constructor found for Intent(JSONTask,Class<AnswerActivity>)
constructor Intent.Intent(String,Uri) is not applicable
(argument mismatch; JSONTask cannot be converted to String)
constructor Intent.Intent(Context,Class<?>) is not applicable
(argument mismatch; JSONTask cannot be converted to Context)

Error:(69, 14) error: no suitable method found for makeText(Intent,String,int)
method Toast.makeText(Context,CharSequence,int) is not applicable
(argument mismatch; Intent cannot be converted to Context)
method Toast.makeText(Context,int,int) is not applicable
(argument mismatch; Intent cannot be converted to Context)

what did I miss here? thank you

Upvotes: 3

Views: 1843

Answers (5)

MikeKeepsOnShine
MikeKeepsOnShine

Reputation: 1750

The better approach is create a constructor in the class

Context context;

public void init(Context ctx){
       this.context = ctx;
}

Then you can create the Toast

Toast.makeText(this.context, result, Toast.LENGTH_LONG).show();

Upvotes: 0

Abhishek Jain
Abhishek Jain

Reputation: 3702

If you are not using JSONTask class anywhere else then you can define it within your AnswerActivity as an inner class. If you do that then this code should work,

Toast.makeText(AnswerActivity.this, result, Toast.LENGTH_LONG).show();

Otherwise you have to pass your application context to the JSONTask and use that within Toast.

public class JSONTask extends AsyncTask<String, String, String> {

    private Context appContext;

    public JSONTask(Context context){
        this.appContext= context;
    }

    @Override
    protected String doInBackground(String... params) {

    //--- some code cut here ---//

    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);    
        Toast.makeText(appContext, result, Toast.LENGTH_LONG).show();
    }
}

Upvotes: 0

W4R10CK
W4R10CK

Reputation: 5550

Remove this:

    Intent i = new Intent(this, AnswerActivity.class);
    Toast.makeText(i, result, Toast.LENGTH_LONG).show();

With this:

Pass Context in AsyncTask class:

public class JSONTask extends AsyncTask<String, String, String> {
private Context context;
//in constructor:
public JSONTask(Context context){
    this.context=context;
}

@Override
protected String doInBackground(String... params) {

//--- some code cut here ---//

}

@Override
protected void onPostExecute(String result) {
    super.onPostExecute(result);


    Toast.makeText(context, result, Toast.LENGTH_LONG).show();
}
}

And use this in Activity:

new JSONTask(AnswerActivity.this).execute("https://example.com/api.php");

Upvotes: 2

alex samsung
alex samsung

Reputation: 110

Your JSONTask should be

public class JSONTask extends AsyncTask<String, String, String> {

    Context mContext;

    public JSONTask(Context mContext) {
        this.mContext = mContext;
    }

    @Override
    protected String doInBackground(String... params) {
        //--- some code cut here ---//
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        Toast.makeText(mContext, result, Toast.LENGTH_LONG).show();
    }
}

Initialization

 new JSONTask(this).execute("https://example.com/api.php");

Upvotes: 2

Murat Karag&#246;z
Murat Karag&#246;z

Reputation: 37594

You need a context to show a Toast. Usually it's the Activity or the Fragment having the context. But since your AsyncTask is not a inner class of your AnswerActivity you have no reference to a context. So you could pass the Activity in the constructor and use that

public class JSONTask extends AsyncTask<String, String, String> {

    private Context context;

    public JSONTask(Context context){
      this.context = context;
    }

    @Override
    protected void onPostExecute(String result) {
        Toast.makeText(context, result, Toast.LENGTH_LONG).show();
    }
}

And use it with 

new JSONTask(this)... // and so on

The big advantage of this is, that you do not keep a reference to the Activity and just pass the Context - since Activity does extend the Context.

Upvotes: 5

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