CODEWITHSUNDEEP
javaandroideclipsecrash
Joey Sides
Joey Sides

Reputation: 67

Android app force close when executed

Execution of the following code crashed. There are no error messages.

It should open Web.java upon a button press and creates a Key-Value.

MainActivity.java

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Spinner;

public class MainActivity extends Activity {

    private Button btnGo;
    final Spinner page = (Spinner)findViewById(R.id.txtPage);
    String pageChoice;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final SharedPreferences sharedPref =PreferenceManager.getDefaultSharedPreferences(this);
        btnGo = (Button)findViewById(R.id.btnGo);
        btnGo.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                pageChoice = page.getSelectedItem().toString();

                //Hopefully will allow for "global" url setting.
                SharedPreferences.Editor editor = sharedPref.edit();
                editor.putString("key1", pageChoice);
                editor.commit();
                startActivity(new Intent(MainActivity.this, Web.class));
            }
        });
    }
}

Upvotes: 0

Views: 69

Answers (2)

Dhaval Patel
Dhaval Patel

Reputation: 10299

Put final Spinner page = (Spinner)findViewById(R.id.txtPage); after setContentView(R.layout.activity_main); statment

findViewById (int id)

Look for a child view with the given id. If this view has the given id, return this view. So While class load it looks for Spinner with txtPage id but it isn’t there. so you are getting null value. Which you are trying to access in onClick Method result is NPE.

Upvotes: 1

Deividi Cavarzan
Deividi Cavarzan

Reputation: 10110

This not suppose to be in class variables:

final Spinner page = (Spinner)findViewById(R.id.txtPage);

This need to be inside onCreate()method. After setContentView(), as a method variable.

findViewById() use the context to lookup the View, and this need to have a context (and the layout resource need to be inflated). You only get the context in onCreate execution, not when the class is loaded.

Upvotes: 1

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