有时劳科德鲁格的答案并不管用。我是这样做的，经过了一些尝试和错误:

public static void showKeyboard(Activity activity) {
    if (activity != null) {
        activity.getWindow()
                .setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
    }
}

public static void hideKeyboard(Activity activity) {
    if (activity != null) {
        activity.getWindow()
                .setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
    }
}

EditText部分:

    editText.setOnFocusChangeListener(new View.OnFocusChangeListener() {
        @Override
        public void onFocusChange(View v, boolean hasFocus) {
            if (!hasFocus) {
                hideKeyboard(getActivity());
            } else {
                showKeyboard(getActivity());
            }
        }
    });

在Activity的onResume()部分，你可以调用方法bringKeyboard();

 onResume() {
     EditText yourEditText= (EditText) findViewById(R.id.yourEditText);
     bringKeyboard(yourEditText);
 }


  protected boolean bringKeyboard(EditText view) {
    if (view == null) {
        return false;
    }
    try {
      // Depending if edittext has some pre-filled values you can decide whether to bring up soft keyboard or not
        String value = view.getText().toString();
        if (value == null) {
            InputMethodManager imm = (InputMethodManager)context.getSystemService(Context.INPUT_METHOD_SERVICE);
            imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
            return true;
        }
    } catch (Exception e) {
        Log.e(TAG, "decideFocus. Exception", e);
    }
    return false;
  }

信不信由你，当我发现活动动画可以禁用软键盘时，我的软键盘问题得到了解决。当你用

i.setFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);

and

overridePendingTransition(0, 0);

它可以隐藏软键盘，没有办法显示它。

如果EditText是在回收器或ListView和/或这有禁用状态使用下面的代码。

public static void showKeyboardByFocus(final View view)
    {
        view.requestFocus();

        InputMethodManager keyboard = SystemMaster.getInputMethodManager();
        keyboard.showSoftInput(view, InputMethodManager.SHOW_IMPLICIT);

        Runnable re = new Runnable()
        {
            @Override
            public void run()
            {
                view.setEnabled(true);
                view.requestFocus();
            }
        };

        Handler h = new Handler(Looper.getMainLooper());
        h.postDelayed(re, 360);
    }

我用定时器。键盘可以显示编辑文本聚焦。

    edittext = (EditText) findViewById(R.id.edittext );
    edittext.requestFocus();
    edittext.setFocusableInTouchMode(true);
    if (edittext.requestFocus()) {
        final Thread timer = new Thread() {
            public void run() {
                try{
                    sleep(500);
                    InputMethodManager imm =(InputMethodManager) getApplicationContext().getSystemService(INPUT_METHOD_SERVICE);
                    imm.showSoftInput(edittext, SHOW_IMPLICIT);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        };
        timer.start();

editText.post(new Runnable() {
    @Override
    public void run() {
        InputMethodManager imm = (InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
        imm.showSoftInput(editText, InputMethodManager.SHOW_IMPLICIT);
    }
});