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buttonOnClick switch isn't working

One of the activities in my app has three buttons in it and I used a switch to code them. I've used nearly identical code several other times in my app, but this particular one doesn't work. When I navigate to this screen and click any of the three buttons, nothing happens.
Here's the code that isn't working:
public void buttonOnClick(View view){
switch(view.getId()){
case R.id.generalPrefabButton:
Intent generalPrefabScreen = new Intent();
generalPrefabScreen.setClass(this, General_Prefab_Order.class);
startActivity(generalPrefabScreen);
break;
case R.id.conduitBendButton:
Intent conduitBendScreen = new Intent();
conduitBendScreen.setClass(this, Conduit_Bend_Order.class);
startActivity(conduitBendScreen);
break;
case R.id.safetyReportButton:
Intent safetyReportScreen = new Intent();
safetyReportScreen.setClass(this, Safety_Report.class);
startActivity(safetyReportScreen);
}
}

One way of achieving this is to make your class implement OnClickListener and then add it to your buttons like this:
Example:
//make your class implement OnClickListener
public class MyClass implements OnClickListener{ ... //Create your buttons and set their onClickListener to "this"
Button generalPrefabButton = (Button) findViewById(R.id.buttonplay);
generalPrefabButton.setOnClickListener(this);
Button conduitBendButton = (Button) findViewById(R.id.buttonstop);
conduitBendButton.setOnClickListener(this); ...
//implement the onClick method here
public void onClick(View v) {
// Perform action on click
switch(v.getId()) {
case R.id.generalPrefabButton:
Intent generalPrefabScreen = new Intent();
generalPrefabScreen.setClass(this, General_Prefab_Order.class);
startActivity(generalPrefabScreen);
break;
case R.id.conduitBendButton:
Intent conduitBendScreen = new Intent();
conduitBendScreen.setClass(this, Conduit_Bend_Order.class);
startActivity(conduitBendScreen);
break;
case R.id.safetyReportButton:
Intent safetyReportScreen = new Intent();
safetyReportScreen.setClass(this, Safety_Report.class);
startActivity(safetyReportScreen);
break;
}
}

Button button = new Button(R.id.generalPrefabButton);
button.setOnClickListener(this);
This sets the onClickListener activating the action in the onClick method.

Add this line to your Buttons in the layout .xml file:
android:onClick="buttonOnClick"
<Button
android:id="#+id/button"
android:onClick="buttonOnClick"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>

how I process NullPointerException on android? [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 6 years ago.
I want
when I click the button.
showing Connectingreceiver.class
but NullpointerException.
I think I not well use context.
advice for me
thanks android senior developer.
private OnClickListener mConnectOnClick = new OnClickListener() {
Context context= ConfiguredNetworkContent.this;
#Override
public void onClick(View v) {
Intent intent = new Intent(context,Connectingreceiver.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
public class Connectingreceiver extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.connecting_dialog);
}
}

Check this :
private View.OnClickListener mConnectOnClick = new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), Connectingreceiver.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
v.getContext().startActivity(intent);
}
Update :
Straight forward explanation is you need a Context to start a Activity. And in Onclick() there is a passing View in which Context already existed. So, I only used it to start activity.

where this context? Context context;
fix Context context = getApplicationContext;

Try this
// Add this line after Main class
Button yourButton;
In below code don't forget to edit "yourButtonIDfromXML"
// Add below code in OnCreate method after setContentView
Button yourButton = (Button) findViewById(R.id.yourButtonIDfromXML);
yourButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(ConfiguredNetworkContent.this, Connectingreceiver.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
finish();
}
});

The "context" - is null. You need to do null check s to avoid Null Pointer Crash. It is the easiest exception to resolve.
If your are doing OnClick event in
Activity:- Use these lines.
public static void startReceiver() {
Intent intent = new Intent(YourActivityName.this, Connectingreceiver.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}
Fragment :-
Use these lines
private OnClickListener mConnectOnClick = new OnClickListener() {
Context context;
#Override
public void onClick(View v) {
if(getActivity() != null) {
startActivity(getActivity());
}
}
And use same the startActivity() method
Also, rename your startActivity method. It is an inbuilt android method.
Prefer using camel cases for your class name. Connectingreceiver --> ConnectingReceiver.

I think I not well use context.
You have to use it if needed, But as per your codes there is no initialization of context.
First initialize your context either with ApplicationContext or ActivityContext like here
Context context = YourActivity.this;
then you can use startActivity(intent);. You don't need to write context.startActivity(intent);. only startActivity will be enough at all.
UPDATE :
Do not pass any context their just simply do
customstartActivity();
And inside customstartActivity() method
public static void customstartActivity (){
// Intent intent = new Intent(yourActivity.this, Connectingreceiver.class);
// Intent intent = new Intent(ContextWrapper.getBaseContext(), Connectingreceiver.class);
Intent intent = new Intent(getApplicationContext(), Connectingreceiver.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}

Button working only on second click [duplicate]

This question already has answers here:
Android Button Works Only on the second Click
(2 answers)
Closed 7 years ago.
I have a simple, but annoying problem:
In my fragment, I have a button which should open another activity (intent) on click. However I have to click the button twice, and only the second time it's opening the activity.
Here is the xml layout of the button:
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Go!"
android:onClick="login"
android:id="#+id/bt_SignIn"
android:layout_below="#+id/pass"
android:layout_centerHorizontal="true"
android:layout_marginTop="70dp" />
And here is the code for onClick:
public void login(View view){
bt_SignIn = (Button) findViewById(R.id.bt_SignIn);
bt_SignIn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(), Frontpage.class);
startActivity(i);
}
}
}

You're setting the onClick listener for the button twice. You're declaring the onClick in the XML so your method can just be.
public void login(View view){
Intent i = new Intent(getApplicationContext(), Frontpage.class);
startActivity(i);
}

Why are you defining Onclick listener for btn_signIn again? As you already define in your xml login method will call on button click.
Use only below code.
public void login(View view) {
Intent i = new Intent(getApplicationContext(), Frontpage.class);
startActivity(i);
}

That is because of thee fact that in the function defined in xml you are setting the listener for the button. Do it from either the JAVA code or from the xml code.
This shall suffice
public void login(View view) {
Intent i = new Intent(getApplicationContext(), Frontpage.class);
startActivity(i);
}
What was happening earlier was that on the first click the function defined in the xml was getting invoked which inturn was setting the listener for the button, and so on the next click your activity was getting triggered

You should avoid to use onClick directly in the XML, it's a bad idea.
Remove onClick from the XML:
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Go!"
android:id="#+id/bt_SignIn"
android:layout_below="#+id/pass"
android:layout_centerHorizontal="true"
android:layout_marginTop="70dp" />
put this code in the onCreate of your Activity:
bt_SignIn = (Button) findViewById(R.id.bt_SignIn);
bt_SignIn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(), Frontpage.class);
startActivity(i);
}
}

Change your login(View view) method as follows
public void login(View view){
Intent i = new Intent(getApplicationContext(), Frontpage.class);
startActivity(i);
}
Or much better put your code inside onCreate() method
bt_SignIn = (Button) findViewById(R.id.bt_SignIn);
bt_SignIn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(), Frontpage.class);
startActivity(i);
}
}
and remove onClick from your layout
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Go!"
android:id="#+id/bt_SignIn"
android:layout_below="#+id/pass"
android:layout_centerHorizontal="true"
android:layout_marginTop="70dp" />

Multiple activities and buttons?

I want to make buttons once I click on the button I go to another activity?
and the problem is only the first button is working!
public class Main extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button PageOneButton = (Button) findViewById(R.id.btnPageOne);
PageOneButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent myIntent = new Intent(v.getContext(), PageOne.class);
v.getContext().startActivity(myIntent);
Button PageTwo = (Button) findViewById(R.id.btnPageTwo);
PageTwoButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent myIntent = new Intent(v.getContext(), PageTwo.class);
v.getContext().startActivity(myIntent);
}
{}
});
}
});
}
}

Think it is because most of your code is closed inside the scope of the first onClickListener, try something like this.
Button PageOneButton = (Button) findViewById(R.id.btnPageOne);
PageOneButton.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
Intent myIntent = new Intent(Main.this, PageOne.class);
startActivity(myIntent);
});
Button PageTwoButton = (Button) findViewById(R.id.btnPageTwo);
PageTwoButton.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
Intent myIntent = new Intent(Main.this, PageTwo.class);
startActivity(myIntent);
});
Using v.getContext() should be ok, this is just how I usually would do as the Activity itself is indeed a valid context. I guess it just seems more readable to me.
Edit:
Just as a clarification to the current state of your code. The second button is assigned a onClickListener only after the first button is pressed. But since the first button takes the app to a new Activity, inherently destroying the Main Activity, the second button will never have a chance to reach it's onClickListener.
Hope it makes sense, nevertheless the code above should fix the issue.

There are a couple of issues currently in your code. The first issue is that your second button is being defined inside the first button's declaration. The next issue is that you're setting the second OnClickListener to the wrongly named button. You've made a typo and instead of PageTwo, which you've called the Button (presumably you wanted to call it PageTwoButton in accordance with the first Button) and then set the OnClickListener to PageTwoButton instead. Seeing as you're also using multiple Buttons, it's a lot cleaner and more efficient to use a GroupOnClickListener. I'd probably also suggest using 'this' instead of 'v.getContext()' as well when setting up your Intents. Change your code to be like so:
Button PageOneButton = (Button) findViewById(R.id.btnPageOne);
Button PageTwoButton = (Button) findViewById(R.id.btnPageTwo);
PageOneButton.setOnClickListener(addGroupOnClickListener);
PageTwoButton.setOnClickListener(addGroupOnClickListener);
private OnClickListener addGroupOnClickListener = new OnClickListener() {
public void onClick(View v) {
if (v == PageOneButton) {
Intent myIntent = new Intent(Main.this, PageOne.class);
startActivity(myIntent);
} else if (v == PageTwoButton) {
Intent myIntent = new Intent(Main.this, PageTwo.class);
startActivity(myIntent);
}
}
};
Hope this helps!

Two words: Code Indentation
Were you to indent your code properly, you would have noticed that you're setting OnClickListener INSIDE your first buttons' listener. Move it outside your first listener, as has already been advised by others.
There's also an extra pair of {}, which is redundant.
Also, #edwoollard noticed that for the second button, you're using two different names, PageTwo and PageTwoButton. Keep that in mind, unless it's a typo.

How to navigate from one screen to another screen

How to navigate from one Activity screen to another Activity screen? In the first screen I'm having one button if I click the button it has to move to another Activity screen.

The most trivial case (called from activity):
startActivity(new Intent(this, ActivityToLaunch.class));
More details here: http://developer.android.com/guide/topics/fundamentals.html

OnClickListener onClickListener = new OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(action));
}
};
Button button = (Button) findViewById(id);
button.setOnClickListener(onClickListener);

Button x.setOnClickListener(new View.OnClickListener() {
public void onClick(View v)
{
Intent i = new Intent(y.this, Activity.class);
startActivity(i);
}
});
Here we've defined a listener for Button x. The OS will call this method and start the Activity referenced in Intent i.
Here's the official tutorial example:
http://developer.android.com/guide/tutorials/notepad/notepad-ex2.html

Button btn = (Button)findViewById(R.id.button1);
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(TestActivity.this,second.class));
}
});

public void onClick(View v)
{
Intent myintent = new Intent(currentclass.this, nextactivity.class);
startActivity(myintent);
}

This task can be accomplished using one of the android's main building block named as Intents and One of the methods public void startActivity (Intent intent) which belongs to your Activity class.
An intent is an abstract description of an operation to be performed. It can be used with startActivity to launch an Activity, broadcastIntent to send it to any interested BroadcastReceiver components, and startService(Intent) or bindService(Intent, ServiceConnection, int) to communicate with a background Service.
An Intent provides a facility for performing late runtime binding between the code in different applications. Its most significant use is in the launching of activities, where it can be thought of as the glue between activities. It is basically a passive data structure holding an abstract description of an action to be performed.
Refer the official docs -- http://developer.android.com/reference/android/content/Intent.html
public void startActivity (Intent intent) -- Used to launch a new activity.
So suppose you have two Activity class and on a button click's OnClickListener() you wanna move from one Activity to another then --
PresentActivity -- This is your current activity from which you want to go the second activity.
NextActivity -- This is your next Activity on which you want to move.
So the Intent would be like this
Intent(PresentActivity.this, NextActivity.class)
Finally this will be the complete code
public class PresentActivity extends Activity {
protected void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.content_layout_id);
final Button button = (Button) findViewById(R.id.button_id);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on click
Intent activityChangeIntent = new Intent(PresentActivity.this, NextActivity.class);
// currentContext.startActivity(activityChangeIntent);
PresentActivity.this.startActivity(activityChangeIntent);
}
});
}
}
This exmple is related to button click you can use the code anywhere which is written inside button click's OnClickListener() at any place where you want to switch between your activities.

final Context cont = this;
Button btnClickABC =(Button)findViewById(R.id.btnClickABC);
btnClickABC.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(cont, NextActivity.class));
}
});

Use following code..I hope this will help you.
Button button = (Button)findViewById(R.id.xxx);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Intent intent=new Intent(CurrentActivity.this,NextActivity.class);
startActivity(intent);
}
});
xxx is id from your xml of your Button.

startActivity(new Intent(this,newActivity.class));

Switching from one activity to another is really simple, but tricky for a new one.
Your next class must be defined in AndroidManifest.xml. This is tester class:
<activity
android:name=".Tester"
android:label="#string/title_activity_tester" >`enter code here`
</activity>
final Button button = (Button) findViewById(R.id.btnGo);// btnGo is id
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent i = new Intent(CurrentClass.this, Tester.class);
startActivity(i);
}

You can navigate to the next screen using these code snippets:
Kotlin
startActivity(Intent(this, LoginActivity::class.java))
Java
startActivity(new Intent(this, LoginActivity.class))
Here's a reference: Android Developers - Starting another activity

Intent intentobj=new Intent(FromActivity.this,ToActivity.class);
startActivity(intentobj);
or you can simply use
startActivity(new Intent(FromActivity.this,ToActivity.class));

For Kotlin (if you are in an activity)
buttonToClick.setOnClickListener{ startActivity(this,YourDestinationActivity::class.java)
}
If you are in a fragment
buttonToClick.setOnClickListener{
startActivity(requireActivity, YourDestinationActivity::class.java)
}

In your method fun onCreate(savedInstanceState: Bundle?) add this.
your_btn_id.setOnClickListener{
val intent = Intent(this, yourpagename::class.java)
startActivity(intent)
}
Until now if it doesn't work then, check if these two files are added or not,
import android.content.Intent
import kotlinx.android.synthetic.main.activity_otp.*

Try this code:
Button my_btn;
my_btn = findViewById(R.id.submit_btn);
my_btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
setContentView(R.layout.activity_2);
}
});

Button navigate;
navigate = findViewById(R.id.button);
navigate.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(getApplicationContext(),"Navigate another Activity",Toast.LENGTH_LONG).show();
Intent intent = new Intent(MainActivity.this,MainActivity2.class);
startActivity(intent);
}
});

Just go to XML file and add Onclick = "opennewactivity" in button xml.
Then go to java code and create class opennewactivity you can just make it my clciking alt+Enter in xml code's "opennewactivity". in that just write
Intent intent = new Intent(this, newacivity.class);
startActivity(intent);
and if you want user to not get back to first activity again then just write this
Intent intent = new Intent(this, newactivity.class);
startActivity(intent);
finish();

Cartoon_card.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v)
{
newActivity();
}
});
}
public void newActivity()
{
Intent selectClass= new Intent(getApplicationContext(), com.example.fyp.videoplayer.class);
startActivity(selectClass);
}