Question 137921 in Android Studio Question posted in
The official documentation can be found here.

Android Studio – AlertDialog in seperate class to use in entire project

I tried to use a seperate class in which Alertdialog is called for showing message. But app crashes without any error



package com.example.library;

import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.widget.Toast;

public class java_class {

    public void msgbox(Context context, String msg)
    {
        AlertDialog.Builder dlgAlert  = new AlertDialog.Builder(context.getApplicationContext());
        dlgAlert.setMessage(msg)
                .setCancelable(false)
                .setPositiveButton("Ok",
                        new DialogInterface.OnClickListener()
                        {
                            public void onClick(DialogInterface dialog, int which)
                            {
                                //Toast.makeText(context, "test", Toast.LENGTH_SHORT).show();
                                // no action
                            }
                        })
                .show();
    }
}

in MainActivity i called it this way..

        Context context= getApplicationContext();
        java_class msbox=new java_class();
        msbox.msgbox(context,"Test");

when used debugger it ran upto ‘public void onClick(DialogInterface dialog, int which)’ line were app crashed.

but when i used the msgbox(String msg) in Mainactivity as function it works fine.

pls help…

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    2023-05-05 21:46:25.102 24043-24043 AndroidRuntime com.example.library E FATAL EXCEPTION: main Process: com.example.library, PID: 24043 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.library/com.example.library.MainActivity}: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running? at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3645) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3782) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:101) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2307) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loopOnce(Looper.java:201) at android.os.Looper.loop(Looper.java:288) at android.app.ActivityThread.main(ActivityThread.java:7872) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:936) Caused by: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running? at android.view.ViewRootImpl.setView(ViewRootImpl.java:1312) at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:405) at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148) at android.app.Dialog.show(Dialog.java:352) at android.app.AlertDialog$Builder.show(AlertDialog.java:1131) at com.example.library.javaclass.msgbox(javaclass.java:23) at com.example.library.MainActivity.onCreate(MainActivity.java:32) at android.app.Activity.performCreate(Activity.java:8305) at android.app.Activity.performCreate(Activity.java:8284) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1417) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3626) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3782)  at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:101)  at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)  at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2307)  at android.os.Handler.dispatchMessage(Handler.java:106)  at android.os.Looper.loopOnce(Looper.java:201)  at android.os.Looper.loop(Looper.java:288)  at android.app.ActivityThread.main(ActivityThread.java:7872)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:936)  2023-05-05 21:46:25.663 24043-24043 Process com.example.library I Sending signal. PID: 24043 SIG: 9 ---------------------------- PROCESS ENDED (24043) for package com.example.library ----------------------------

    This is screen shot of debugger... it goes till line. once it reaches "public void onClick(DialogInterface dialog, int which)" debugger crashes


  2. 0

    There’s no need to ask app context from context.

    import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;


public class JavaClass {

    public void msgbox(Context context, String msg)
    {
        AlertDialog.Builder dlgAlert  = new AlertDialog.Builder(context); //<- this changed 
        dlgAlert.setMessage(msg)
                .setCancelable(false)
                .setPositiveButton("Ok",
                        new DialogInterface.OnClickListener()
                        {
                            public void onClick(DialogInterface dialog, int which)
                            {
                                //Toast.makeText(context, "test", Toast.LENGTH_SHORT).show();
                                // no action
                            }
                        })
                .show();
    }
}

    also you can use this to get context in activity class.

    JavaClass javaClass = new JavaClass();
javaClass.msgbox(this, "Hello World2");

    In Android, we can use the this keyword to get the context of the current Activity instance. When used inside an Activity, this refers to that Activity instance, which is a subclass of the Context class. If used inside a listener, we can reference the current context by using the Activity name, such as MainActivity.this in Java or this@MainActivity in Kotlin.

    enter image description here

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search