AlertDialog with EditText, open soft keyboard automatically with focus on EditText doesn't work

Ok I managed to get it working:

Builder builder = new Builder(this);
            final EditText input = new EditText(this);
            builder
                .setTitle(R.string.dialog_title_addsubject)
                .setMessage(R.string.dialog_addsubject)
                .setView(input)
                .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {

                    public void onClick(DialogInterface dialog, int which) {
                        String value = input.getText().toString();
                        if (input.getText().toString().trim().length() == 0) {
                            Toast.makeText(Main.this, R.string.input_empty, Toast.LENGTH_SHORT).show();
                        } else {
                            db.insertSubject(value);
                            getData();
                        }
                        InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
                        imm.hideSoftInputFromWindow(input.getWindowToken(), 0);
                    }
                })
                .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {

                    public void onClick(DialogInterface dialog, int which) {
                        InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
                        imm.hideSoftInputFromWindow(input.getWindowToken(), 0);
                    }

                });

                builder.show();
                input.requestFocus();
                InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
                imm.toggleSoftInput(InputMethodManager.SHOW_FORCED, 0);

This method doesn't need a dialog so I can use builder.show() to show the dialog and the code provided by Sabre opens the soft keyboard. Another code snippet in each of the buttons closes the soft keyboard automatically.

You can use this instead of dialog.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_VISIBLE);:

InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
imm.toggleSoftInput(InputMethodManager.SHOW_FORCED, 0);

Call this after dialog.show();

   public void selectContact(Context context) {
        AlertDialog.Builder builder = new AlertDialog.Builder(context);
        builder.setIcon(R.mipmap.icon);
        builder.setTitle(R.string.title);
        builder.setPositiveButton(android.R.string.ok, context);
        builder.setNegativeButton(android.R.string.cancel,context);
        builder.setView(View.inflate(context,
                R.layout.dialog, null));
        AlertDialog alertDialog = builder.create();

        alertDialog.setOnShowListener(this); //Add listener
        alertDialog.show();
    }

open keyborad in onShow :-

    @Override
    public void onShow(DialogInterface dialog) {
        EditText editText = (EditText) ((AlertDialog) dialog).findViewById(R.id.number);
        InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
        imm.showSoftInput(editText, InputMethodManager.SHOW_IMPLICIT);
    }