看看https://stackoverflow.com/a/39144104/2914140，我简化了一点:

// In onCreateView():
view.edit_text.run {
    requestFocus()
    post { showKeyboard(this) }
}

fun showKeyboard(view: View) {
    val imm = view.context.getSystemService(
        Context.INPUT_METHOD_SERVICE) as InputMethodManager?
    imm?.showSoftInput(view, InputMethodManager.SHOW_IMPLICIT)
}

它比https://stackoverflow.com/a/11155404/2914140:好

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

因为当你按Home键并移动到主屏幕时，键盘会保持打开状态。

这是一个很好的例子:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ScrollView
        android:id="@+id/scrollID"
        android:layout_width="fill_parent"
        android:layout_height="0dip"
        android:layout_weight="1" >

        <LinearLayout
            android:id="@+id/test"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical" >
        </LinearLayout>
    </ScrollView>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:baselineAligned="true"
        android:orientation="horizontal"
        android:paddingBottom="5dp"
        android:paddingLeft="5dp"
        android:paddingRight="5dp"
        android:weightSum="1" >

        <EditText
            android:id="@+id/txtInpuConversation"
            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_weight="0.5"
            android:hint="@string/edt_Conversation" >

            <requestFocus />
        </EditText>

        <Button
            android:id="@+id/btnSend"
            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_weight="0.5"
            android:text="@string/btn_Conversation" />
    </LinearLayout>

</LinearLayout>

edittext.setShowSoftInputOnFocus(真正的);是关于这个问题的最流畅的解决方案。

AlertDialog.Builder alertSearch = new AlertDialog.Builder(activity);
alertSearch.setIcon(R.drawable.ic_launcher);
alertSearch.setTitle("Search");
final EditText edittext = new EditText(activity);
edittext.setSingleLine();
edittext.setHint("...");
edittext.setText(SearchString);

在聚焦时设置键盘

edittext.setShowSoftInputOnFocus(true);

获得焦点

edittext.requestFocus();

And

alertSearch.setView(edittext);
alertSearch.setPositiveButton("OK", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int whichButton) {
        // Do something
        act.recreate();
    }
});
alertSearch.show();

是的，你可以用setOnFocusChangeListener来做，它会帮助你。

editText.setOnFocusChangeListener(new View.OnFocusChangeListener() {
    @Override
    public void onFocusChange(View v, boolean hasFocus) {
        if (hasFocus) {
            dialog.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
        }
    }
});

要显示键盘，对我来说，我必须执行以下操作

Android文本字段:设置焦点+软输入编程

基本上解决方案如下

@Override
public void onResume() {
    super.onResume();
    //passwordInput.requestFocus(); <-- that doesn't work
    passwordInput.postDelayed(new ShowKeyboard(), 325); //250 sometimes doesn't run if returning from LockScreen
}

ShowKeyboard在哪里

private class ShowKeyboard implements Runnable {
    @Override
    public void run() {
        passwordInput.setFocusableInTouchMode(true);
        //passwordInput.requestFocusFromTouch(); //this gives touch event to launcher in background -_-
        passwordInput.requestFocus();
        getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
        ((InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE)).showSoftInput(passwordInput, 0);
    }
}

在成功输入之后，我还确保隐藏了键盘

getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
((InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE))
                    .hideSoftInputFromWindow(getView().getWindowToken(), 0);

将这些方法放在Util类中，并在任何地方使用。

科特林

fun hideKeyboard(activity: Activity) {
    val view = activity.currentFocus
    val methodManager = activity.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    assert(view != null)
    methodManager.hideSoftInputFromWindow(view!!.windowToken, InputMethodManager.HIDE_NOT_ALWAYS)
}

private fun showKeyboard(activity: Activity) {
    val view = activity.currentFocus
    val methodManager = activity.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    assert(view != null)
    methodManager.showSoftInput(view, InputMethodManager.SHOW_IMPLICIT)
}

Java

public static void hideKeyboard(Activity activity) {
    View view = activity.getCurrentFocus();
    InputMethodManager methodManager = (InputMethodManager) activity.getSystemService(Context.INPUT_METHOD_SERVICE);
    assert methodManager != null && view != null;
    methodManager.hideSoftInputFromWindow(view.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
}

private static void showKeyboard(Activity activity) {
    View view = activity.getCurrentFocus();
    InputMethodManager methodManager = (InputMethodManager) activity.getSystemService(Context.INPUT_METHOD_SERVICE);
    assert methodManager != null && view != null;
    methodManager.showSoftInput(view, InputMethodManager.SHOW_IMPLICIT);
}