如何调用setInputView方法来呈现不同的键盘

Question

我来自javascript背景，这是我第一次使用java。

我一直关注this guide。我有一个完全工作的键盘，现在我想开始定制它。我想要做的第一件事是在按下键时显示符号。

在挖掘之后看起来setInputView可能就是我需要的东西，但我不确定如何调用它？有一个switch语句控制我认为我能够挂钩的符号的大小写但是当我调用该方法时，我得到错误Attempt to invoke interface method 'void android.inputmethodservice.KeyboardView$OnKeyboardActionListener.onPress(int)' on a null object reference，我认为这是因为我认为我正在调用的函数，我其实并没打电话。

以下是我到目前为止的相关java代码：

package com.example.crhistian.spanishsymbolskeyboard;

import android.inputmethodservice.InputMethodService;
import android.inputmethodservice.KeyboardView;
import android.inputmethodservice.Keyboard;
import android.view.View;
import android.view.inputmethod.InputConnection;
import android.view.KeyEvent;
import android.media.AudioManager;
public class SpanishSymbols extends InputMethodService
    implements KeyboardView.OnKeyboardActionListener{

private KeyboardView kv;
private Keyboard keyboard;
private KeyboardView spanishkv;

private boolean caps = false;

@Override
public void onKey(int primaryCode, int[] keyCodes) {
    InputConnection ic = getCurrentInputConnection();
    playClick(primaryCode);
    switch(primaryCode){
        case Keyboard.KEYCODE_DELETE :
            ic.deleteSurroundingText(1, 0);
            break;
        case Keyboard.KEYCODE_MODE_CHANGE :
            setInputView(spanishkv);
            break;
        case Keyboard.KEYCODE_SHIFT:
            caps = !caps;
            keyboard.setShifted(caps);
            kv.invalidateAllKeys();
            break;
        case Keyboard.KEYCODE_DONE:
            ic.sendKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_ENTER));
            break;
        default:
            char code = (char)primaryCode;
            if(Character.isLetter(code) && caps){
                code = Character.toUpperCase(code);
            }
            ic.commitText(String.valueOf(code),1);
    }
}

@Override
public void onPress(int primaryCode) {
}

@Override
public void onRelease(int primaryCode) {
}

@Override
public void onText(CharSequence text) {
}

@Override
public void swipeDown() {
}

@Override
public void swipeLeft() {
}

@Override
public void swipeRight() {
}

@Override
public void swipeUp() {
}

@Override
public View onCreateInputView() {
    kv = (KeyboardView)getLayoutInflater().inflate(R.layout.keyboard, null);
    keyboard = new Keyboard(this, R.xml.keyboard);
    spanishkv = (KeyboardView)getLayoutInflater().inflate(R.layout.spanishsymbols, null);
    spanishkv.setKeyboard(keyboard);
    kv.setKeyboard(keyboard);
    kv.setOnKeyboardActionListener(this);
    return kv;
}

private void playClick(int keyCode){
    AudioManager am = (AudioManager)getSystemService(AUDIO_SERVICE);
    switch(keyCode){
        case 32:
            am.playSoundEffect(AudioManager.FX_KEYPRESS_SPACEBAR);
            break;
        case Keyboard.KEYCODE_DONE:
        case 10:
            am.playSoundEffect(AudioManager.FX_KEYPRESS_RETURN);
            break;
        case Keyboard.KEYCODE_DELETE:
            am.playSoundEffect(AudioManager.FX_KEYPRESS_DELETE);
            break;
        default: am.playSoundEffect(AudioManager.FX_KEYPRESS_STANDARD);
    }
}

}