Question

Hey guys im trying to make a dynamic scrollable list of selectiondata which a user can add or remove a spinner and editText when they need to. I have the Spinner and editText being added without an issue, but when i try to delete the one on the bottom of the list.. I get a null pointer error.

At first i thought it was because i was not referencing them properly (relevant editText and spinner data is held in a hashmap) however i have printed out the key names and they appear correct.

Here is the code..

Variables

int count = 0;
HashMap<String,Spinner> spinnerMap = new HashMap<String,Spinner>();
HashMap<String,EditText> editTextMap = new HashMap<String,EditText>();
LinearLayout horzLayout;
LinearLayout layout;

addRow method

 public void addRow()
    {
        Toast.makeText(getApplicationContext(), "editText"+count, Toast.LENGTH_SHORT).show();
        layout = (LinearLayout) findViewById(R.id.scrollerLayout);  
        LinearLayout horzLayout = new LinearLayout(this);
        LinearLayout.LayoutParams p = new LinearLayout.LayoutParams(
                LinearLayout.LayoutParams.MATCH_PARENT,
                LinearLayout.LayoutParams.WRAP_CONTENT
        );
        editTextMap.put("editText"+count, new EditText(this));
        editTextMap.get("editText"+count).setWidth(100);
        editTextMap.get("editText"+count).setHeight(40);
        spinnerMap.put("spinner"+count, new Spinner(this));
        List<String> spinnerItems = new ArrayList<String>();
        spinnerItems.add("Super Duper Bad Evil Weed");
        spinnerItems.add("Super Duper Edible Weed");
        spinnerItems.add("Funky Looking Weed");
        spinnerItems.add("Special Weed");

        ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, spinnerItems);
        dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinnerMap.get("spinner"+count).setAdapter(dataAdapter);
        horzLayout.setOrientation(LinearLayout.HORIZONTAL);
        layout.addView(horzLayout, p);
        horzLayout.addView(spinnerMap.get("spinner"+count));
        horzLayout.addView(editTextMap.get("editText"+count));
        count++;

    }

RemoveRow Method

    public void removeRow()
{
    count--;
    Toast.makeText(getApplicationContext(), "editText"+count, Toast.LENGTH_SHORT).show();
    horzLayout.removeView(spinnerMap.get("spinner"+count));
    spinnerMap.remove("spinner"+count);
    horzLayout.removeView(editTextMap.get("editText"+count));
    editTextMap.remove("editText"+count);

}

Exact Error Message..

> 06-09 23:48:33.369: E/AndroidRuntime(560): FATAL EXCEPTION: main
06-09 23:48:33.369: E/AndroidRuntime(560): java.lang.NullPointerException
06-09 23:48:33.369: E/AndroidRuntime(560):  at org.unisa.paddockpad.ScreenTwo.removeRow(ScreenTwo.java:83)
06-09 23:48:33.369: E/AndroidRuntime(560):  at org.unisa.paddockpad.ScreenTwo$2.onClick(ScreenTwo.java:52)
06-09 23:48:33.369: E/AndroidRuntime(560):  at android.view.View.performClick(View.java:3511)
06-09 23:48:33.369: E/AndroidRuntime(560):  at android.view.View$PerformClick.run(View.java:14105)
06-09 23:48:33.369: E/AndroidRuntime(560):  at android.os.Handler.handleCallback(Handler.java:605)
06-09 23:48:33.369: E/AndroidRuntime(560):  at android.os.Handler.dispatchMessage(Handler.java:92)
06-09 23:48:33.369: E/AndroidRuntime(560):  at android.os.Looper.loop(Looper.java:137)
06-09 23:48:33.369: E/AndroidRuntime(560):  at android.app.ActivityThread.main(ActivityThread.java:4424)
06-09 23:48:33.369: E/AndroidRuntime(560):  at java.lang.reflect.Method.invokeNative(Native Method)
06-09 23:48:33.369: E/AndroidRuntime(560):  at java.lang.reflect.Method.invoke(Method.java:511)
06-09 23:48:33.369: E/AndroidRuntime(560):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
06-09 23:48:33.369: E/AndroidRuntime(560):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
06-09 23:48:33.369: E/AndroidRuntime(560):  at dalvik.system.NativeStart.main(Native Method)

Any help would be greatly appreciated!

update

I am able to delete the views right after they are created inside that method.

Answer 1

horzLayout initialized in addRow ( as local variable ) but not in remove row (where it global)…