I couldn't see the java.lang.NullPointerException error

Question

Can Anyone help me please? explain to me why this code is "java.lang.NullPointerException" error.

final ImageButton sampleImageButton = (ImageButton) findViewById(R.id.btn_sample);

    final Dialog dd_dialog = new Dialog(MainActivity.this);
    dd_dialog.setContentView(R.layout.Sample_layout);
    dd_dialog.setTitle("Sample");
    dd_dialog.setCancelable(true);

sampleImageButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    dd_dialog.show();
                }
            });

here's the xml

<Button android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btn_sample"
        android:text="Sample"
        android:background="#4372AA"
        android:layout_marginRight="10dp"
        android:paddingLeft="10dp"
        android:paddingRight="10dp"
        android:textColor="#FFFFFF"
        android:layout_marginTop="30dp"/>

i already edit the code.. but the error is pointing to this code sampleImageButton.setOnClickListener(new View.OnClickListener() { — Kiel, Jan 13 '16 at 09:56
hmmm,getting `NPE` because probably ImageView is inside layout of Dialog. so try it as :`final ImageButton sampleImageButton = (ImageButton) dd_dialog .findViewById(R.id.btn_sample); ` — ρяσѕρєя K, Jan 13 '16 at 09:56
Possible duplicate of [What is a Null Pointer Exception, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — yennsarah, Jan 13 '16 at 09:57
@ρяσѕρєя K actually the error is pointing to this part sampleImageButton.setOnClickListener(new View.OnClickListener() { — Kiel, Jan 13 '16 at 09:58
@anupDasari here's the logcat errors FATAL EXCEPTION: main Process: sample.sample.com.sampledesign, PID: 32593 java.lang.NullPointerException — Kiel, Jan 13 '16 at 10:02
at sample.sample.com.sampledesign.MainActivity$3.onClick(MainActivity.java:116) at android.view.View.performClick(View.java:4637) at android.view.View$PerformClick.run(View.java:19422) — Kiel, Jan 13 '16 at 10:03
at android.os.Handler.handleCallback(Handler.java:733) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5479) — Kiel, Jan 13 '16 at 10:03
at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283) — Kiel, Jan 13 '16 at 10:03
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099) at dalvik.system.NativeStart.main(Native Method) — Kiel, Jan 13 '16 at 10:03
@ρяσѕρєя here's the new structure of the codes: final Dialog dd_dialog = new Dialog(MainActivity.this); final ImageButton sampleImageButton = (ImageButton) dd_dialog.findViewById(R.id.btn_sample); dd_dialog.setContentView(R.layout.Sample_layout); dd_dialog.setTitle("Sample"); dd_dialog.setCancelable(true); then the onclicklistener here — Kiel, Jan 13 '16 at 10:14
@ρяσѕρєяK I found the problem just now, thanks for the effort :) — Kiel, Jan 13 '16 at 10:18

Akhi Prajapati · Accepted Answer · 2016-01-13T10:15:18.870

1

problem is here you have taken button in xml layout and in java file you declare ImageButton so change from ImageButton to Button.

change this line from

final ImageButton sampleImageButton = (ImageButton) findViewById(R.id.btn_sample);

To

final Button sampleImageButton = (Button) findViewById(R.id.btn_sample);

edited Jan 13 '16 at 10:15

answered Jan 13 '16 at 10:07

Akhi Prajapati

147
3

score 0 · Answer 2 · answered Jan 13 '16 at 09:58

0

It looks like that you haven't set the activity view using setContentView before using findViewById

Hope this helps.

answered Jan 13 '16 at 09:58

Mustansar Saeed

2,730
2
22
46

score 0 · Answer 3 · answered Jan 13 '16 at 09:59

probably this must be the correction :

final ImageButton sampleImageButton = (ImageButton) dd_dialog.findViewById(R.id.btn_sample);

add this below of

final Dialog dd_dialog = new Dialog(MainActivity.this);
dd_dialog.setContentView(R.layout.Sample_layout);

I couldn't see the java.lang.NullPointerException error

3 Answers3