CODEWITHSUNDEEP
androidnullpointerexception
Joseph Little-Indelible
Joseph Little-Indelible

Reputation: 643

How do I fix this nullpointerexception in my android activity?

package org.example.mbtiapplication;

import java.util.ArrayList;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;

public class MBTITest extends Activity implements OnItemSelectedListener   {

    Spinner firstSpinner = (Spinner) findViewById(R.id.spinner1);
    Spinner secondSpinner = (Spinner) findViewById(R.id.spinner2);
    Spinner thirdSpinner = (Spinner) findViewById(R.id.spinner3);
    Spinner fourthSpinner = (Spinner) findViewById(R.id.spinner4);
    ArrayList<String> Evaluator = new ArrayList<String>();



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_mbtitest);
        addItemsOnSpinner1();
        addItemsOnSpinner2();
        addItemsOnSpinner3();
        addItemsOnSpinner4();

    }

    public void addItemsOnSpinner1(){   
        Spinner firstSpinner = (Spinner) findViewById(R.id.spinner1);
        // Create an ArrayAdapter using the string array and a default spinner layout
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
                R.array.spinnerarraybool, android.R.layout.simple_spinner_item);
        // Specify the layout to use when the list of choices appears
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        // Apply the adapter to the spinner
        firstSpinner.setAdapter(adapter);


    }

    public void addItemsOnSpinner2(){   
        Spinner firstSpinner = (Spinner) findViewById(R.id.spinner2);
        // Create an ArrayAdapter using the string array and a default spinner layout
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
                R.array.spinnerarraybool, android.R.layout.simple_spinner_item);
        // Specify the layout to use when the list of choices appears
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        // Apply the adapter to the spinner
        firstSpinner.setAdapter(adapter);
    }

    public void addItemsOnSpinner3(){   
        Spinner firstSpinner = (Spinner) findViewById(R.id.spinner3);
        // Create an ArrayAdapter using the string array and a default spinner layout
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
                R.array.spinnerarraybool, android.R.layout.simple_spinner_item);
        // Specify the layout to use when the list of choices appears
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        // Apply the adapter to the spinner
        firstSpinner.setAdapter(adapter);
    }

    public void addItemsOnSpinner4(){   
        Spinner firstSpinner = (Spinner) findViewById(R.id.spinner4);
        // Create an ArrayAdapter using the string array and a default spinner layout
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
                R.array.spinnerarraybool, android.R.layout.simple_spinner_item);
        // Specify the layout to use when the list of choices appears
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        // Apply the adapter to the spinner
        firstSpinner.setAdapter(adapter);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View arg1, int arg2,
            long arg3) {
        switch (parent.getId()){
        case R.id.spinner1:
            String firstAnswer = firstSpinner.getSelectedItem().toString();
            Evaluator.add(firstAnswer);
        case R.id.spinner2:
            String secondAnswer = firstSpinner.getSelectedItem().toString();
            Evaluator.add(secondAnswer);
        case R.id.spinner3:
            String thirdAnswer = firstSpinner.getSelectedItem().toString();
            Evaluator.add(thirdAnswer);
        case R.id.spinner4:
            String fourthAnswer = firstSpinner.getSelectedItem().toString();
            Evaluator.add(fourthAnswer);

        }


    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0) {
        // TODO Auto-generated method stub

    }

}

Stacktrace:

11-24 14:06:55.778: E/AndroidRuntime(1842): FATAL EXCEPTION: main
11-24 14:06:55.778: E/AndroidRuntime(1842): Process: org.example.mbtiapplication, PID: 1842
11-24 14:06:55.778: E/AndroidRuntime(1842): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{org.example.mbtiapplication/org.example.mbtiapplication.MBTITest}: java.lang.NullPointerException
11-24 14:06:55.778: E/AndroidRuntime(1842):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2102)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at android.app.ActivityThread.access$700(ActivityThread.java:135)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at android.os.Handler.dispatchMessage(Handler.java:102)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at android.os.Looper.loop(Looper.java:137)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at android.app.ActivityThread.main(ActivityThread.java:4998)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at java.lang.reflect.Method.invokeNative(Native Method)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at java.lang.reflect.Method.invoke(Method.java:515)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at dalvik.system.NativeStart.main(Native Method)
11-24 14:06:55.778: E/AndroidRuntime(1842): Caused by: java.lang.NullPointerException
11-24 14:06:55.778: E/AndroidRuntime(1842):     at android.app.Activity.findViewById(Activity.java:1883)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at org.example.mbtiapplication.MBTITest.<init>(MBTITest.java:15)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at java.lang.Class.newInstanceImpl(Native Method)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at java.lang.Class.newInstance(Class.java:1208)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
11-24 14:06:55.778: E/AndroidRuntime(1842):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2093)
11-24 14:06:55.778: E/AndroidRuntime(1842):     ... 11 more

When I press on my button to start my new activity, I get this in my log cat and an error telling me that my application has stopped. I am not sure on how to fix this issue still after doing some research and would like to know how I can fix this problem as it occurs. Thank you

Upvotes: 0

Views: 249

Answers (1)

Raghunandan
Raghunandan

Reputation: 133570

Move the initialization in onCreate after setContentView as below

Spinner firstSpinner ;
Spinner secondSpinner ;
Spinner thirdSpinner;
Spinner fourthSpinner ;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_mbtitest); 
    // initialize after setting the layout to the activity 
     firstSpinner = (Spinner) findViewById(R.id.spinner1);
     secondSpinner = (Spinner) findViewById(R.id.spinner2);
     thirdSpinner = (Spinner) findViewById(R.id.spinner3);
     fourthSpinner = (Spinner) findViewById(R.id.spinner4);
     ... //rest of the code  
}

Also there is no need to initialize spinner again remove the spinner initialization in addItemsOnSpinner2() just use firstSpinner since its a class memner. Same for others.

   Spinner firstSpinner = (Spinner) findViewById(R.id.spinner2);

Upvotes: 1

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