null into array from loop

Question

this answer comes from here: 2Darray to 1darray with for loop

I don´t know if I can reopen it once it was answered.. my apologies if that's the case.

I modified a little that function to end like this:

public  String[] initarray() {

xFINAL = new String [data_array.length];
int i = 0;
int j=0;
int UMB1 = 100;
int l = data_array.length;

for (i=0 ; i < l ; i++) {
        LATIT = Double.parseDouble(data_array [i][2]);
        LONGIT = Double.parseDouble(data_array [i][3]); 

        dist = calculateDistanceByHaversineFormula(Localizacion.LONGITUD_D, Localizacion.data_arrayUD_D,LONGIT,  LATIT);

        if (dist < UMB1){

            xFINAL[j++] = data_array [i][0];
                    System.out.println(Arrays.toString(xFINAL));
                    System.out.println("j++" + data_array[i][0]);

                }

            }

return xFINAL;

}

dist = the difference in meters between 2 locations, returning an int.

data_array is already defined before.

It's "kind of working". What I get from that code is an array like this(data1 and data3 are inside the condition, data2 would be false)

[data1 , data3 , null]

And should be like this instead I think:

[data1, data3]

The error comes when I am trying to use that xFINAL array with an spinner:

public final void rel() {




String[] array_spinner = MYSQL.xFINAL;

    ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_spinner_dropdown_item, array_spinner);
    spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    sp_1.setAdapter(spinnerArrayAdapter);
}

When I try to load the spinner it gives me the following:

03-25 13:25:26.367: E/AndroidRuntime(30843): FATAL EXCEPTION: main
03-25 13:25:26.367: E/AndroidRuntime(30843): java.lang.NullPointerException
03-25 13:25:26.367: E/AndroidRuntime(30843):    at     android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at  android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at  android.widget.Spinner.measureContentWidth(Spinner.java:681)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.widget.Spinner.onMeasure(Spinner.java:442)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.View.measure(View.java:15518)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:681)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.View.measure(View.java:15518)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:681)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.View.measure(View.java:15518)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.View.measure(View.java:15518)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:847)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.View.measure(View.java:15518)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2176)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.View.measure(View.java:15518)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.Choreographer.doCallbacks(Choreographer.java:562)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.Choreographer.doFrame(Choreographer.java:532)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.os.Handler.handleCallback(Handler.java:725)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.os.Handler.dispatchMessage(Handler.java:92)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.os.Looper.loop(Looper.java:137)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at android.app.ActivityThread.main(ActivityThread.java:5041)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at java.lang.reflect.Method.invokeNative(Native Method)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at java.lang.reflect.Method.invoke(Method.java:511)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-25 13:25:26.367: E/AndroidRuntime(30843):    at dalvik.system.NativeStart.main(Native Method)

If I just get the 3 data into the spinner it works.. so I am lost.

Any help please? :)

Thanks in advance.

[edit]

03-25 19:39:23.081: I/System.out(3501): [00000001]
03-25 19:39:23.081: I/System.out(3501): 00000001
03-25 19:39:23.091: I/System.out(3501): [00000001, 00000003]
03-25 19:39:23.091: D/AndroidRuntime(3501): Shutting down VM
03-25 19:39:23.091: W/dalvikvm(3501): threadid=1: thread exiting with uncaught    exception (group=0x40bac930)
03-25 19:39:23.091: E/AndroidRuntime(3501): FATAL EXCEPTION: main
03-25 19:39:23.091: E/AndroidRuntime(3501): java.lang.IndexOutOfBoundsException:   Invalid index 2, size is 2
03-25 19:39:23.091: E/AndroidRuntime(3501):     at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:251)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at java.util.ArrayList.get(ArrayList.java:304)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at com.example.mvlpres.c_sql.recorre_array2(c_sql.java:635)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at com.example.mvlpres.SincronizacionFragment$1.onClick(SincronizacionFragment.java:179)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at android.view.View.performClick(View.java:4204)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at android.view.View$PerformClick.run(View.java:17355)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at android.os.Handler.handleCallback(Handler.java:725)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at android.os.Handler.dispatchMessage(Handler.java:92)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at android.os.Looper.loop(Looper.java:137)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at android.app.ActivityThread.main(ActivityThread.java:5041)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at java.lang.reflect.Method.invokeNative(Native Method)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at java.lang.reflect.Method.invoke(Method.java:511)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-25 19:39:23.091: E/AndroidRuntime(3501):     at dalvik.system.NativeStart.main(Native Method)

Achintya Jha · Accepted Answer · 2013-03-25 17:28:50Z

1

 System.out.println(Arrays.toString(xFINAL));

This line should be after for loop completes.

For references (anything that holds an object) that is null.

For int/short/byte that is a 0.

For float/double that is a 0.0

For booleans that is a false.

When you create an array of String, all entries are null initially. Your array size is 3 I think so initially it is initialized with [null,null, null]. Two null get replaced with the values and one remains as it is.

EDIT: Use ArrayList instead Array

List<String> list = new ArrayList<String>();
for (i=0 ; i < l ; i++) {
    LATIT = Double.parseDouble(data_array [i][2]);
    LONGIT = Double.parseDouble(data_array [i][3]); 

    dist = calculateDistanceByHaversineFormula(Localizacion.LONGITUD_D, Localizacion.data_arrayUD_D,LONGIT,  LATIT);

    if (dist < UMB1){

        list.add(data_array [i][0]);
                System.out.println(list);
                System.out.println(list.get(i));

     }

}

edited Mar 25, 2013 at 17:28

answered Mar 25, 2013 at 13:51

Achintya Jha

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8 Comments

user2097111 Over a year ago

Ok. I get what you mean. But then, why does it crash when I try to load the array into the spinner? If the last null is actually null cause the condition is false, should the spinner just ignore it? Thanks for your response.

user2097111 Over a year ago

Copy it where? I'm getting lost :p I did a quick test, and indeed the spinner can´t read that third null into the array, the thing is.. how can I make the xFINAL array only as big as the true results from the condition not as big as data_array.length? Thanks for your help.

Achintya Jha Over a year ago

@user2097111 You are getting NPE because of null in array . So I suggest you to use ArrayList instead of Array.

user2097111 Over a year ago

Ok. And Can I somehow use my 2dArray with an ArrayList directly? I ask this because if I try to get an array from my data_array[][] to use it as List.add it's gonna be a fixed array again... I am so confused! :p

Achintya Jha Over a year ago

@user2097111 See my edit section. Try this one , I hope it will solve your problem.

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