dynamic buttons Android Layout

Question

I want to create a layout in Android in a java class. I need that the user introduce a number between 1 to 20 and this create the number of butttons that the user has chosen.I want to create dynamic buttons and I have this code:

package com.example.nuevo;

import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.LinearLayout;

public class ControladorResuelto extends Activity {


protected Controlador controlador;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
     requestWindowFeature(Window.FEATURE_NO_TITLE);
      getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                         WindowManager.LayoutParams.FLAG_FULLSCREEN);


        LinearLayout buttonsLayout =  (LinearLayout)findViewById(R.id.linearlayoutUp); 

    int nMallas = controlador.getnMallas();

    LinearLayout.LayoutParams layoutParams = new     LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
    for(int i=0;i<nMallas;i++){
        Button button = new Button(this);
        button.setText("Buttin "+(i+1));
        buttonsLayout.addView(button, layoutParams);******
    }

    setContentView(R.layout.panel_resuelto);
}

I have an error at the line with asterisks

Yes Embattled Swag, it was that but now I have another problem, the 3 buttons that I have created dynamically were in a vertical layout and now I have changed the linear Layout to horizontal and they don't appear do you what is happening? — user3232094
– user3232094, Commented Feb 24, 2014 at 17:30

Embattled Swag · Accepted Answer · 2014-02-24 17:22:05Z

1

I'm pretty sure it's because you have setContentView(R.layout.panel_resuelto); at the end of your onCreate. Put it at the beginning, else findViewById won't work. I'm guessing you're getting a null pointer exception because the LinearLayout couldn't successfully be created since the content view wasn't set yet.

answered Feb 24, 2014 at 17:22

Embattled Swag

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5 Comments

telkins Over a year ago

More specifically, findViewById won't work until setContentView is created in this case.

user3232094 Over a year ago

Yes Embattled Swag, it was that but now I have another problem, the 3 buttons that I have created dynamically were in a vertical layout and now I have changed the linear Layout to horizontal and they don't appear do you what is happening?

Embattled Swag Over a year ago

I can't really tell. I would suggest creating a new question (with the full code).

user3232094 Over a year ago

here there is my XML layout and the java code is the same with the CotentView changed yet.

user3232094 Over a year ago

Thanks Embattled Swag!! I posted here my XML layout stackoverflow.com/questions/21995038/…

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