public class screen2 extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.screen2);
final Button button1 = (Button)findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
//AInteger.parseInt(string)
System.out.println("1");
EditText et = (EditText)findViewById(R.id.editText1);
System.out.println("2");
int zipCode = Integer.parseInt(et.getText().toString());
System.out.println("3");
System.out.println(zipCode);
System.out.println("dude...5");
}
});
}
}
This code shows the errror in the logcat :
11-13 19:58:06.806: W/KeyCharacterMap(281): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
11-13 19:58:09.471: I/System.out(281): 1
11-13 19:58:09.471: I/System.out(281): 2
11-13 19:58:09.477: D/AndroidRuntime(281): Shutting down VM
11-13 19:58:09.477: W/dalvikvm(281): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
11-13 19:58:09.527: E/AndroidRuntime(281): FATAL EXCEPTION: main
11-13 19:58:09.527: E/AndroidRuntime(281): java.lang.NullPointerException
11-13 19:58:09.527: E/AndroidRuntime(281): at com.example.andtwi.screen2$1.onClick(screen2.java:23)
11-13 19:58:09.527: E/AndroidRuntime(281): at android.view.View.performClick(View.java:2408)
11-13 19:58:09.527: E/AndroidRuntime(281): at android.view.View$PerformClick.run(View.java:8816)
11-13 19:58:09.527: E/AndroidRuntime(281): at android.os.Handler.handleCallback(Handler.java:587)
11-13 19:58:09.527: E/AndroidRuntime(281): at android.os.Handler.dispatchMessage(Handler.java:92)
11-13 19:58:09.527: E/AndroidRuntime(281): at android.os.Looper.loop(Looper.java:123)
11-13 19:58:09.527: E/AndroidRuntime(281): at android.app.ActivityThread.main(ActivityThread.java:4627)
11-13 19:58:09.527: E/AndroidRuntime(281): at java.lang.reflect.Method.invokeNative(Native Method)
11-13 19:58:09.527: E/AndroidRuntime(281): at java.lang.reflect.Method.invoke(Method.java:521)
11-13 19:58:09.527: E/AndroidRuntime(281): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
11-13 19:58:09.527: E/AndroidRuntime(281): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
11-13 19:58:09.527: E/AndroidRuntime(281): at dalvik.system.NativeStart.main(Native Method)
Though it looks like an Null Pointer exception , i think i am doing it things exactly i found on forums. Here is code of my related xml file as well. Can anyone suggest where am i doing it wrong?
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Enter Zipcode" />
<EditText
android:id="#+id/editText1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="number"
android:maxLength="5" >
<requestFocus />
</EditText>
<Button
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Get movies from Flixster" />
</LinearLayout>
The code breaks at this as well :
int zipCode = Integer.parseInt(et.getText().toString());
Try this:
Button button1 = (Button)findViewById(R.id.button1);
EditText et = (EditText)findViewById(R.id.editText1);
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
System.out.println("1");
System.out.println("2");
String zipCode = et.getText().toString();
System.out.println("3");
System.out.println(zipCode);
}
}
I think,you don't need to write String zipCode = (String)et.getText().toString(); there as it is already returns a String object.
And hope,you don't miss to include setContentView(R.layout.your_xml_file); before declaring a Button and EditText.
Edit 1:
You don't seem to get problem with
int zipCode=Integer.parseInt(et.getText().toString()); there.Try this with above code modification.
You might be getting null pointer exception because you are getting String s=et.getText().toString() as null.Please check it for null before casting it to int.
Button button1 = (Button)findViewById(R.id.button1);
EditText et = (EditText)findViewById(R.id.editText1);
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
System.out.println("1");
System.out.println("2");
String check = et.getText().toString();
int zipCode=0;
if(!check.equals(""))
zipCode=Integer.parseInt(check);
System.out.println("3");
System.out.println(zipCode);
}
}
Could you post your onCreate method, as well as line 23 on its own? The most likely problem is that you neglect to call setContentView and that is why findViewById returns null.
Related
I have DialogFragment with custom layout that has an EditText. I am trying to get EditText value on 'ADD' Click but I have been getting NullPointerException and it crashes.
public Dialog onCreateDialog(Bundle savedInstanceState) {
AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(getActivity());
final View view = getActivity().getLayoutInflater().inflate(R.layout.add_note_dialog_fragment, null);
alertDialogBuilder.setView(view);
alertDialogBuilder.setTitle("Add New Note: ");
alertDialogBuilder.setPositiveButton("ADD", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
EditText noteTextEditText = (EditText) view.findViewById(R.id.notesText);
EditText noteTitleEditText = (EditText) view.findViewById(R.id.noteTitle2);
Editable noteText = noteTextEditText.getText();
// ^^^ HERE I GET NULL POINTER EXCEPTION
String y = noteText.toString();
String noteTitle = noteTitleEditText.getText().toString();
DatabaseHelper.addInABSTRACT_NOTES(noteText, noteTitle);
Toast.makeText(getActivity(), "ADDED ..", Toast.LENGTH_SHORT).show();
dialog.dismiss();
}
});
Kindly suggest how can I get it working ?
Thanks in advance.
LogCat:
07-08 00:08:47.030: E/AndroidRuntime(16500): FATAL EXCEPTION: main
07-08 00:08:47.030: E/AndroidRuntime(16500): Process: com.shumail.newsroom, PID: 16500
07-08 00:08:47.030: E/AndroidRuntime(16500): java.lang.NullPointerException
07-08 00:08:47.030: E/AndroidRuntime(16500): at com.g_node.gca.abstracts.AddNoteDialogFragment$1.onClick(AddNoteDialogFragment.java:70)
07-08 00:08:47.030: E/AndroidRuntime(16500): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
07-08 00:08:47.030: E/AndroidRuntime(16500): at android.os.Handler.dispatchMessage(Handler.java:102)
07-08 00:08:47.030: E/AndroidRuntime(16500): at android.os.Looper.loop(Looper.java:136)
07-08 00:08:47.030: E/AndroidRuntime(16500): at android.app.ActivityThread.main(ActivityThread.java:5086)
07-08 00:08:47.030: E/AndroidRuntime(16500): at java.lang.reflect.Method.invokeNative(Native Method)
07-08 00:08:47.030: E/AndroidRuntime(16500): at java.lang.reflect.Method.invoke(Method.java:515)
07-08 00:08:47.030: E/AndroidRuntime(16500): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
07-08 00:08:47.030: E/AndroidRuntime(16500): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
07-08 00:08:47.030: E/AndroidRuntime(16500): at dalvik.system.NativeStart.main(Native Method)
Layout XML:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="#+id/noteTitleLabel" android:text="Note Title: "
android:layout_width="wrap_content" android:layout_height="wrap_content" />
<EditText
android:id="#+id/noteTitle2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="text"
android:hint="Enter Note Title..."
android:gravity="top"
android:layout_below="#+id/noteTitleLabel"
android:singleLine="true" />
<TextView
android:id="#+id/noteTextLabel" android:text="Note Content: "
android:layout_width="wrap_content" android:layout_below="#+id/noteTitle2" android:layout_height="wrap_content" />
<EditText
android:id="#+id/noteText"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="textMultiLine"
android:hint="Enter Note Content..."
android:lines="5"
android:gravity="top"
android:layout_below="#+id/noteTextLabel"
android:singleLine="false" />
The problem was with the ID. I had written R.id.notesText by mistake whereas it was supposed to be R.id.noteText
I have implemented the ViewPager in Fragment in my application which contains the Custom layout. Now in Custom layout of ViewPager there is a TextView and onClick of the TextView i would like to replace the current fragment with other fragment. Lets say with Fragment2.
I already tried to replace but its giving error for the Resource id of the FrameLayout where i want to load the fragment. I already checked the relevant solutions in SO but none helped me.
Please any one can guide me for this error. It would be really grateful and appreciable.
Logcat:
11-13 11:17:54.480: E/AndroidRuntime(3982): FATAL EXCEPTION: main
11-13 11:17:54.480: E/AndroidRuntime(3982): java.lang.IllegalArgumentException: No view found for id 0x7f0600cc for fragment OtherProfileFragment{40ceba28 #4 id=0x7f0600cc}
11-13 11:17:54.480: E/AndroidRuntime(3982): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:865)
11-13 11:17:54.480: E/AndroidRuntime(3982): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1083)
11-13 11:17:54.480: E/AndroidRuntime(3982): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:635)
11-13 11:17:54.480: E/AndroidRuntime(3982): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1431)
11-13 11:17:54.480: E/AndroidRuntime(3982): at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:420)
11-13 11:17:54.480: E/AndroidRuntime(3982): at android.os.Handler.handleCallback(Handler.java:725)
11-13 11:17:54.480: E/AndroidRuntime(3982): at android.os.Handler.dispatchMessage(Handler.java:92)
11-13 11:17:54.480: E/AndroidRuntime(3982): at android.os.Looper.loop(Looper.java:137)
11-13 11:17:54.480: E/AndroidRuntime(3982): at android.app.ActivityThread.main(ActivityThread.java:5041)
11-13 11:17:54.480: E/AndroidRuntime(3982): at java.lang.reflect.Method.invokeNative(Native Method)
11-13 11:17:54.480: E/AndroidRuntime(3982): at java.lang.reflect.Method.invoke(Method.java:511)
11-13 11:17:54.480: E/AndroidRuntime(3982): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
11-13 11:17:54.480: E/AndroidRuntime(3982): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
11-13 11:17:54.480: E/AndroidRuntime(3982): at dalvik.system.NativeStart.main(Native Method)
Here is my code where onclick of TextView i am trying to load the Fragment.
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.activity_feed_detail, container,
false);
m_tvProfileName = (TextView) v.findViewById(R.id.afd_tvProfileName);
m_tvProfileName.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
FragmentManager m_mange = m_context.getSupportFragmentManager();
FragmentTransaction fm = m_mange.beginTransaction();
Fragment llf = new OtherFragment();
Bundle m_bundle = new Bundle();
m_bundle.putInt("Id", Id);
llf.setArguments(m_bundle);
fm.addToBackStack("Other");
fm.replace(R.id.fragmentswitcherframe, llf); //This line throwing error
fm.commit();
getActivity().finish();
}
});
return v;
}
I am new to android application development. I was doing this tutorial app.It's a very simple one. It adds one and subtracts one from the counter.When I run it in the emulator ,it says "Unfortunately tutorial has stopped working." There are no errors in the code. The API level is 17. Please help me out.
Code for java:
public class Startingpoint extends Activity {
int counter=0;
Button add,subtract;
TextView display;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.startingpoint);
add = (Button) findViewById(R.id.bAdd);
subtract= (Button) findViewById(R.id.bSubtract);
display= (Button) findViewById(R.id.text);
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
counter++;
display.setText("The total is " + counter);
}
});
subtract.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
counter--;
display.setText("The total is " + counter);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.startingpoint, menu);
return true;
}
}
Layout code in xml :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView android:id="#+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Your total is 0"
android:textSize="35dp"
android:layout_gravity="center"
android:gravity="center"/>
<Button android:layout_width="250dp"
android:layout_height="wrap_content"
android:text="Add One"
android:layout_gravity="center"
android:textSize="25dp"
android:id="#+id/bAdd"/>
<Button android:layout_width="250dp"
android:layout_height="wrap_content"
android:text="Subtract One"
android:layout_gravity="center"
android:textSize="25dp"
android:id="#+id/bSubtract"/>
</LinearLayout>
Here is the logcat :
03-02 02:45:10.730: D/AndroidRuntime(780): Shutting down VM
03-02 02:45:10.730: W/dalvikvm(780): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
03-02 02:45:10.750: E/AndroidRuntime(780): FATAL EXCEPTION: main
03-02 02:45:10.750: E/AndroidRuntime(780): java.lang.RuntimeException: Unable to start activity ComponentInfo{tutorial.example.tutorial/tutorial.example.tutorial.Startingpoint}: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.access$600(ActivityThread.java:141)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.os.Handler.dispatchMessage(Handler.java:99)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.os.Looper.loop(Looper.java:137)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.main(ActivityThread.java:5041)
03-02 02:45:10.750: E/AndroidRuntime(780): at java.lang.reflect.Method.invokeNative(Native Method)
03-02 02:45:10.750: E/AndroidRuntime(780): at java.lang.reflect.Method.invoke(Method.java:511)
03-02 02:45:10.750: E/AndroidRuntime(780): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-02 02:45:10.750: E/AndroidRuntime(780): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-02 02:45:10.750: E/AndroidRuntime(780): at dalvik.system.NativeStart.main(Native Method)
03-02 02:45:10.750: E/AndroidRuntime(780): Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button
03-02 02:45:10.750: E/AndroidRuntime(780): at tutorial.example.tutorial.Startingpoint.onCreate(Startingpoint.java:22)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.Activity.performCreate(Activity.java:5104)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
03-02 02:45:10.750: E/AndroidRuntime(780): ... 11 more
display= (Button) findViewById(R.id.text);
should be
display= (TextView) findViewById(R.id.text);
Since display is supposed to reference a TextView instance, but you're explictly casting into a Button, and these are not compatible types.
As you got the answer from A-C this time, but for next time in android application development a important suggestion:
Always see the logcat for error, and see the "Caused by:" tag, It specifies what was the cause of the problem with sufficient detail, Also see the line no that caused that error.
And try to find what can be wrong with that line of code.
For example: in your logcat it is showing-
Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button
at tutorial.example.tutorial.Startingpoint.onCreate(Startingpoint.java:22)
So you can try to read the log, and you will understand that in your file Startingpoint.java at line 22 which is located in onCreate method the error is android.widget.TextView cannot be cast to android.widget.Button. So you can easily remove your errors without any help.
Hope that helps not only you current problem but prevented your future time and efforts.
I am new to Android. I am trying to build this tiny app however every time I add the code in bold:
d = (Button) findViewById (R.id.tvDis);
the app crashes and if I remove this line, everything works fine. I am runing this on android 2.2 api 8 version and nexus s emulator.
package com.maximusstudios.numtowords;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity {
/**Called when the activity is first created.*/
int counter;
Button add, sub;
TextView d;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
counter = 0;
add = (Button) findViewById (R.id.bAdd);
**d = (Button) findViewById (R.id.tvDis);**
sub = (Button) findViewById(R.id.bSub);
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
counter++;
}
});
sub.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
counter--;
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
XML CODE:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
tools:context=".MainActivity" >
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Your Total is 0"
android:textSize="20dp"
android:layout_gravity="center"
android:gravity="center"
android:id="#+id/tvDis"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Add one"
android:layout_gravity="center"
android:textSize="20dp"
android:id="#+id/bAdd"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Add one"
android:layout_gravity="center"
android:textSize="20dp"
android:id="#+id/bSub"
/>
</LinearLayout>
Error list:
02-10 18:00:21.452: D/AndroidRuntime(910): Shutting down VM
02-10 18:00:21.452: W/dalvikvm(910): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
02-10 18:00:21.472: E/AndroidRuntime(910): FATAL EXCEPTION: main
02-10 18:00:21.472: E/AndroidRuntime(910): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.maximusstudios.numtowords/com.maximusstudios.numtowords.MainActivity}: java.lang.ClassCastException: android.widget.TextView
02-10 18:00:21.472: E/AndroidRuntime(910): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
02-10 18:00:21.472: E/AndroidRuntime(910): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
02-10 18:00:21.472: E/AndroidRuntime(910): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
02-10 18:00:21.472: E/AndroidRuntime(910): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
02-10 18:00:21.472: E/AndroidRuntime(910): at android.os.Handler.dispatchMessage(Handler.java:99)
02-10 18:00:21.472: E/AndroidRuntime(910): at android.os.Looper.loop(Looper.java:123)
02-10 18:00:21.472: E/AndroidRuntime(910): at android.app.ActivityThread.main(ActivityThread.java:4627)
02-10 18:00:21.472: E/AndroidRuntime(910): at java.lang.reflect.Method.invokeNative(Native Method)
02-10 18:00:21.472: E/AndroidRuntime(910): at java.lang.reflect.Method.invoke(Method.java:521)
02-10 18:00:21.472: E/AndroidRuntime(910): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
02-10 18:00:21.472: E/AndroidRuntime(910): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
02-10 18:00:21.472: E/AndroidRuntime(910): at dalvik.system.NativeStart.main(Native Method)
02-10 18:00:21.472: E/AndroidRuntime(910): Caused by: java.lang.ClassCastException: android.widget.TextView
02-10 18:00:21.472: E/AndroidRuntime(910): at com.maximusstudios.numtowords.MainActivity.onCreate(MainActivity.java:23)
02-10 18:00:21.472: E/AndroidRuntime(910): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-10 18:00:21.472: E/AndroidRuntime(910): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
02-10 18:00:21.472: E/AndroidRuntime(910): ... 11 more
Change to
d = (TextView) findViewById (R.id.tvDis);
Your casting was wrong. With your code, when you do (Button), you are trying to cast the TextView that is returned by findViewById() into a Button, which doesn't work due to them being incompatible types.
You define d as a TextView and try to cast it to a Button
Should be
d = (TextView) findViewById (R.id.tvDis);
The error you're getting is a ClassCastException
I cannot figure out why these 2 buttons are not working, i have a layout file inwhich is created when the user selects a certain theme in my application. With the layout it has a webview it has 2 buttons to goback and goforward.
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:text="Back"
android:layout_alignParentLeft="true"
android:layout_height="wrap_content"
android:background="#drawable/button_blue"
style="#style/ButtonText">
</Button>
<Button
android:id="#+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:background="#drawable/button_blue"
style="#style/ButtonText"
android:text="Forward">
</Button>
<WebView
android:id="#+id/webview01"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1.12" >
This is not the entire layout file, but here is the bit of stuff i am working with for the webview and the 2 buttons, now inside my main activity here is my button code.
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (Prefs.theme.equals("Theme1"))
setContentView(R.layout.main);
else if (Prefs.theme.equals("Theme2"))
setContentView(R.layout.main2);
else if (Prefs.theme.equals("Theme3"))
setContentView(R.layout.main3);
else setContentView(R.layout.main);
btnForward=(Button) findViewById (R.id.button1);
btnBackward=(Button) findViewById (R.id.button2);
btnForward.setOnClickListener(this);
btnBackward.setOnClickListener(this);
// more code within on create .....
// Later in the code
public void onClick(View v) {
switch(v.getId()) {
case R.id.button1:
WebViewClientDemoActivity.web.goBack();
break;
case R.id.button2:
WebViewClientDemoActivity.web.goForward();
break;
}
//
I problem im having is by default it loads main.xml not main3 (which is were the 2 buttons are)
LogCat Errors
07-27 16:00:34.802: E/AndroidRuntime(547): FATAL EXCEPTION: main
07-27 16:00:34.802: E/AndroidRuntime(547): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.jaisonbrooks.enlighten/com.jaisonbrooks.enlighten.WebViewClientDemoActivity}: java.lang.NullPointerException
07-27 16:00:34.802: E/AndroidRuntime(547): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
07-27 16:00:34.802: E/AndroidRuntime(547): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
07-27 16:00:34.802: E/AndroidRuntime(547): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
07-27 16:00:34.802: E/AndroidRuntime(547): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
07-27 16:00:34.802: E/AndroidRuntime(547): at android.os.Handler.dispatchMessage(Handler.java:99)
07-27 16:00:34.802: E/AndroidRuntime(547): at android.os.Looper.loop(Looper.java:123)
07-27 16:00:34.802: E/AndroidRuntime(547): at android.app.ActivityThread.main(ActivityThread.java:3683)
07-27 16:00:34.802: E/AndroidRuntime(547): at java.lang.reflect.Method.invokeNative(Native Method)
07-27 16:00:34.802: E/AndroidRuntime(547): at java.lang.reflect.Method.invoke(Method.java:507)
07-27 16:00:34.802: E/AndroidRuntime(547): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-27 16:00:34.802: E/AndroidRuntime(547): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-27 16:00:34.802: E/AndroidRuntime(547): at dalvik.system.NativeStart.main(Native Method)
07-27 16:00:34.802: E/AndroidRuntime(547): Caused by: java.lang.NullPointerException
07-27 16:00:34.802: E/AndroidRuntime(547): at com.jaisonbrooks.enlighten.WebViewClientDemoActivity.onCreate(WebViewClientDemoActivity.java:75)
07-27 16:00:34.802: E/AndroidRuntime(547): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
07-27 16:00:34.802: E/AndroidRuntime(547): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
07-27 16:00:34.802: E/AndroidRuntime(547): ... 11 more
First in your onCreate method find your buttons by ids :
public class YourActivity extends Activity implements OnClickListener {
Button btnForward;
Button btnBackward;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnForward=(Button) findViewById (R.id.btnForward);
btnBackward=(Button) findViewById (R.id.btnBackward);
//set listeners
btnForward.setOnClickListener(this);
btnBackward.setOnClickListener(this);
// your code here ....
}
#Override
public void onClick(View v ) {
switch(v.getId()) {
case R.id.btnBackward:
WebViewClientDemoActivity.web.goBack();
break;
case R.id.btnForward:
WebViewClientDemoActivity.web.goForward();
break;
}
}
}
It should work. Make sure you don't have 2 buttons with the same #id.
It's a common issue when you multiplicate your buttons from one. (copy/paste)
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:text="Back"
android:layout_alignParentLeft="true"
android:layout_height="wrap_content"
android:background="#drawable/button_blue"
style="#style/ButtonText" />
<Button
android:id="#+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:background="#drawable/button_blue"
style="#style/ButtonText"
android:text="Forward" />
try this.
then later in java code, do this
Button btnNext = (Button) findViewById(R.id.button2);
btnNext.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v)
{
WebViewClientDemoActivity.web.goForward();
}
});
Button btnBack = (Button) findViewById(R.id.button1);
btnNext.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v)
{
WebViewClientDemoActivity.web.goBack();
}
});