新对话框活动未在Android中启动

Question

I have an activity, that starts the Dialog box when the list item is long pressed. I start the activity via this code snippet:

private void showWifiSettings(int arg2) {
                Intent newIntent = new Intent("com.example.searchingwifi.DIALOGACTIVITY");
                startActivity(newIntent);
                }

And, the code in the new Dialog activity is as undersigned.

package com.example.searchingwifi;

import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.v4.app.DialogFragment;
import android.view.LayoutInflater;

public class DialogActivity extends DialogFragment{


    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        // Get the layout inflater
        LayoutInflater inflater = getActivity().getLayoutInflater();

        // Inflate and set the layout for the dialog
        // Pass null as the parent view because its going in the dialog layout
        builder.setView(inflater.inflate(R.layout.dialog, null));


        return builder.create();
    }
}

On long pressing the corresponding list item, the Logcat gives me the following error, and the application stops running.

06-27 12:54:22.150: E/AndroidRuntime(25118): FATAL EXCEPTION: main
06-27 12:54:22.150: E/AndroidRuntime(25118): Process: com.example.searchingwifi, PID: 25118
06-27 12:54:22.150: E/AndroidRuntime(25118): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.searchingwifi/com.example.searchingwifi.DialogActivity}: java.lang.ClassCastException: com.example.searchingwifi.DialogActivity cannot be cast to android.app.Activity
06-27 12:54:22.150: E/AndroidRuntime(25118):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at android.app.ActivityThread.access$800(ActivityThread.java:135)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at android.os.Handler.dispatchMessage(Handler.java:102)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at android.os.Looper.loop(Looper.java:136)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at android.app.ActivityThread.main(ActivityThread.java:5017)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at java.lang.reflect.Method.invokeNative(Native Method)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at java.lang.reflect.Method.invoke(Method.java:515)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at dalvik.system.NativeStart.main(Native Method)
06-27 12:54:22.150: E/AndroidRuntime(25118): Caused by: java.lang.ClassCastException: com.example.searchingwifi.DialogActivity cannot be cast to android.app.Activity
06-27 12:54:22.150: E/AndroidRuntime(25118):    at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
06-27 12:54:22.150: E/AndroidRuntime(25118):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2112)
06-27 12:54:22.150: E/AndroidRuntime(25118):    ... 11 more

Can anyone help me with the error, and where am I making the mistake ?

EDIT :- Even if simply starting a new Dialog Activity, the system is still giving the error. The LogCat is as given below.

06-30 03:54:10.550: E/AndroidRuntime(1175): FATAL EXCEPTION: main
06-30 03:54:10.550: E/AndroidRuntime(1175): Process: com.example.testingdialog, PID: 1175
06-30 03:54:10.550: E/AndroidRuntime(1175): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.testingdialog/com.example.testingdialog.MainActivity}: java.lang.ClassCastException: com.example.testingdialog.MainActivity cannot be cast to android.app.Activity
06-30 03:54:10.550: E/AndroidRuntime(1175):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at android.os.Handler.dispatchMessage(Handler.java:102)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at android.os.Looper.loop(Looper.java:136)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at android.app.ActivityThread.main(ActivityThread.java:5017)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at java.lang.reflect.Method.invokeNative(Native Method)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at java.lang.reflect.Method.invoke(Method.java:515)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at dalvik.system.NativeStart.main(Native Method)
06-30 03:54:10.550: E/AndroidRuntime(1175): Caused by: java.lang.ClassCastException: com.example.testingdialog.MainActivity cannot be cast to android.app.Activity
06-30 03:54:10.550: E/AndroidRuntime(1175):     at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
06-30 03:54:10.550: E/AndroidRuntime(1175):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2112)
06-30 03:54:10.550: E/AndroidRuntime(1175):     ... 11 more

Answer 1

You should check this: http://developer.android.com/guide/topics/ui/dialogs.html#ShowingADialog

A dialog isn't the same as an Activity.

Currently you must have

public class MainActivity extends Activity{
...

change this to

public class MainActivity extends FragmentActivity{
...

Then for showing your Dialog add this code in your FragmentActivity

public void showDialog() {
DialogActivity newDialog = new DialogActivity();
newDialog.show(getSupportFragmentManager(), "myDialog");

}

Tip: Do not call your custom Dialog class like DialogActivity, but something like MyCustomDialog (not using "Activity" in the class name)

Answer 2

Here you are opening DialogFragment. Please try with below code.

DialogFragment newFragment = new DialogActivity();
newFragment.show(getFragmentManager(), "dialog");

Hope it will help

Updated: Here you are setting LayoutInflator instead of view. That is why it is giving error of input argument. Try below:

@Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        // Get the layout inflater
        View view = getActivity().getLayoutInflater().inflate(R.layout.dialog, null);
        builder.setView(view);

        return builder.create();
    }
}

Answer 3

You are trying to start activity which is actually DialogFragment . Either make it as DialogActivity and start as activity like this:

Intent intent=new Intent(getApplicationContext(), DialogActivity.class);
startActivity(intent);

OR

You can keep it as Dialogragment only, and show as dialogfragment instead of starting a new activity.

Example:

MyDialogFragment myDialogFragment = new MyDialogFragment();
myDialogFragment.show(fragManager, "myDialogFragment");

Reference Links:

Dialog Fragment example

Dialog Activity example