I am displaying image in the activity by calling other class but it is not displaying the image it is showing me the error.my code is as follow
public class VideosActivity extends Activity {
//DrawView draw;
float a=0;
float b=0;
ImageView image;
MotionEvent event;
Button back ;
Button next;
TextView t;
String info = "";
int count =0;
FirstImage i= new FirstImage (this);
TableLayout tl;
TableRow ru,rm,rl,rlm;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.videos_layout);
i=(FirstImage)findViewById(R.id.first);
//back = (Button) findViewById(R.id.button1);
// next = (Button) findViewById(R.id.button2);
//
// addListenerOnButton();
}
private void addListenerOnButton() {
// TODO Auto-generated method stub
if (count == 0)
back.setEnabled(false);
next.setOnClickListener( new OnClickListener() {
public void onClick(View arg0) {
if(count==0){
image.setImageResource(R.drawable.hand);
back.setEnabled(true);
count++;
addListenerOnButton();
}
else if (count==1){
image.setImageResource(R.drawable.tissue);
count++;
addListenerOnButton();
}
else if (count==2){
image.setImageResource(R.drawable.cellconstfinal1);
count++;
addListenerOnButton();
}
else if (count==3){
//nucleus
image.setImageResource(R.drawable.cellconstfinal1);
count++;
addListenerOnButton();
}
else if (count==4){
//nchromosome
image.setImageResource(R.drawable.hand);
count++;
addListenerOnButton();
}
else
{ //double helix
count++;
image.setImageResource(R.drawable.handash1);
next.setEnabled(false);
addListenerOnButton();
}
}
});
back.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
if(count==1){
image.setImageResource(R.drawable.human);
back.setEnabled(false);
count--;
addListenerOnButton();
}
else if (count==2){
image.setImageResource(R.drawable.hand);
count--;
addListenerOnButton();
}
else if (count==3){
image.setImageResource(R.drawable.tissue);
count--;
addListenerOnButton();
}
else if (count==4){
image.setImageResource(R.drawable.cellconstfinal1);
count--;
addListenerOnButton();
}
else if (count==5){
//nucleus
image.setImageResource(R.drawable.tissue);
count--;
addListenerOnButton();
}
else {
//chromosome
//count==6
image.setImageResource(R.drawable.cellconstfinal1);
count--;
addListenerOnButton();
next.setEnabled(true);
}
}
});
}
it is showing me the following error.i am not understanding why it is showing me following error.
05-10 19:27:32.097: E/AndroidRuntime(638): FATAL EXCEPTION: main
05-10 19:27:32.097: E/AndroidRuntime(638): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.androidtablayout/com.example.androidtablayout.VideosActivity}: java.lang.NullPointerException
05-10 19:27:32.097: E/AndroidRuntime(638): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.app.ActivityThread.startActivityNow(ActivityThread.java:2503)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:127)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:339)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:651)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.widget.TabHost.setCurrentTab(TabHost.java:323)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.widget.TabHost$2.onTabSelectionChanged(TabHost.java:129)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.widget.TabWidget$TabClickListener.onClick(TabWidget.java:453)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.view.View.performClick(View.java:2408)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.view.View$PerformClick.run(View.java:8816)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.os.Handler.handleCallback(Handler.java:587)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.os.Handler.dispatchMessage(Handler.java:92)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.os.Looper.loop(Looper.java:123)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.app.ActivityThread.main(ActivityThread.java:4627)
05-10 19:27:32.097: E/AndroidRuntime(638): at java.lang.reflect.Method.invokeNative(Native Method)
05-10 19:27:32.097: E/AndroidRuntime(638): at java.lang.reflect.Method.invoke(Method.java:521)
05-10 19:27:32.097: E/AndroidRuntime(638): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
05-10 19:27:32.097: E/AndroidRuntime(638): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
05-10 19:27:32.097: E/AndroidRuntime(638): at dalvik.system.NativeStart.main(Native Method)
05-10 19:27:32.097: E/AndroidRuntime(638): Caused by: java.lang.NullPointerException
05-10 19:27:32.097: E/AndroidRuntime(638): at android.content.ContextWrapper.getResources(ContextWrapper.java:80)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.view.View.<init>(View.java:1810)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.widget.ImageView.<init>(ImageView.java:103)
05-10 19:27:32.097: E/AndroidRuntime(638): at com.example.androidtablayout.FirstImage.<init>(FirstImage.java:8)
05-10 19:27:32.097: E/AndroidRuntime(638): at com.example.androidtablayout.VideosActivity.<init>(VideosActivity.java:27)
05-10 19:27:32.097: E/AndroidRuntime(638): at java.lang.Class.newInstanceImpl(Native Method)
05-10 19:27:32.097: E/AndroidRuntime(638): at java.lang.Class.newInstance(Class.java:1429)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
05-10 19:27:32.097: E/AndroidRuntime(638): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577)
05-10 19:27:32.097: E/AndroidRuntime(638): ... 18 more
05-10 19:27:41.897: I/Process(638): Sending signal. PID: 638 SIG: 9
first image .jav code is present here ………..
public class FirstImage extends ImageView {
public FirstImage(Context context) {
super(context);
// TODO Auto-generated constructor stub
}
}
videos layout is code is as follow ….
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<!-- Screen Design for VIDEOS -->
<TableLayout
android:id="@+id/tablelayout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:stretchColumns="1">
<TableRow
android:id="@+id/tableRow1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="15dip"
android:text="pic on click which will tell where is the dna located in human body or cell "
android:textSize="18dip" />
</TableRow>
<TableRow
android:id="@+id/tableRow2"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<FrameLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<com.example.AndroidTablayout.FirstImage
android:id="@+id/first"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:src="@drawable/human"/>
</FrameLayout>
</TableRow>
<TableRow
android:id="@+id/tableRow3"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<LinearLayout
android:id="@+id/linearLayout1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<Button
android:id="@+id/button1"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:text="Back" />
<Button
android:id="@+id/button2"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:text="Next" />
</LinearLayout>
</TableRow>
<TableRow
android:id="@+id/tableRow4"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="15dip"
android:text="please don't mind "
android:textSize="18dip" />
</TableRow>
</TableLayout>
</ScrollView>
EDIT:
Check this answer:
custom image view android
Maybe you need to implement the constructor with the AttributeSet parameter.