java - speech.speak 抛出空指针异常

Question

我写了这个应用程序，实际上我想提供说话功能。但是在添加这个之后，要说的文字就不起作用了。我在 speech.speak(text, TextToSpeech.QUEUE_FLUSH, null);

处收到空指针异常

import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.Random;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.speech.tts.TextToSpeech;
import android.text.Html;
import android.text.method.ScrollingMovementMethod;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;


@SuppressLint("NewApi")
public class BestQuotes_MainActivity extends Activity implements OnClickListener,TextToSpeech.OnInitListener
{
    int IMAGE_FIRST = 0;
    int IMAGE_LAST = 40;
    int CURRENT_IMAGE = 0;

    private String m_sText = null;
    private TextToSpeech speech;

    List<String> quotes = new ArrayList();
    Context mContext = null;
    ImageButton bSpeakerButton;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_best_quotes_main);
        mContext = getBaseContext();
        quotes = (new LoadContents()).populateList();
        addImages();
        Button bShareButton = (Button) findViewById(R.id.shareButton);
        bSpeakerButton = (ImageButton) findViewById(R.id.speaker);
        bShareButton.setOnClickListener(this);
        bSpeakerButton.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                speak();
            }

        });
    }

    private void speak()
    {
        String text = getText();
        speech.speak(text, TextToSpeech.QUEUE_FLUSH, null); //throwing null pointer exception here
    }
    private void addImages() {

        Random rand = new Random();
        int randomNum = rand.nextInt(quotes.size() - 1 - IMAGE_FIRST + 1)
        + IMAGE_FIRST;
        CURRENT_IMAGE = randomNum;

        Log.e("CNH", "Rand value=" + randomNum);

        TextView tv = (TextView) findViewById(R.id.quote);
        tv.setMovementMethod(new ScrollingMovementMethod());
        tv.setTextSize(20);
        tv.setGravity(Gravity.LEFT|Gravity.CENTER_VERTICAL);

        String text = quotes.get(randomNum);
        setText(text);
        text = text.replace("\n", "<br />");
        tv.setGravity(Gravity.LEFT|Gravity.CENTER_VERTICAL);
        tv.setText(Html.fromHtml("<b>" + getText() + "</b>"));


        ImageButton imgNext = (ImageButton) findViewById(R.id.imgnext);
        ImageButton imgPrevious = (ImageButton) findViewById(R.id.imgprevious);

        imgNext.setImageResource(R.drawable.next);
        imgPrevious.setImageResource(R.drawable.previous);
        findViewById(R.id.imgnext).setOnClickListener(new HandleClick());
        findViewById(R.id.imgprevious).setOnClickListener(new HandleClick());
    }

    private class HandleClick implements OnClickListener {
        public void onClick(View view) {
            if (view.getId() == findViewById(R.id.imgnext).getId()) {

                int id = getNextImageNumber(1);

                TextView tv;
                tv = (TextView) findViewById(R.id.quote);
                tv.setTextSize(20);

                String text = quotes.get(id);
                setText(text);
                text = text.replace("\n", "<br />");
                tv.setGravity(Gravity.LEFT|Gravity.CENTER_VERTICAL);
                tv.setText(Html.fromHtml("<b>" + text + "</b>"));

            } else if (view.getId() == findViewById(R.id.imgprevious).getId()) {

                int id = getNextImageNumber(2);

                TextView tv = (TextView) findViewById(R.id.quote);
                tv.setMovementMethod(new ScrollingMovementMethod());
                tv.setTextSize(20);


                String text = quotes.get(id);
                text = text.replace("\n", "<br />");
                setText(text);
                tv.setGravity(Gravity.LEFT|Gravity.CENTER_VERTICAL);
                tv.setText(Html.fromHtml("<b>" + text + "</b>"));

            }
        }

    }

    public int getNextImageNumber(int nextOrPrevious) {
        IMAGE_LAST = quotes.size() - 1;
        if (nextOrPrevious == 1) {
            if (CURRENT_IMAGE == IMAGE_LAST) {
                CURRENT_IMAGE = IMAGE_FIRST;
            } else {
                CURRENT_IMAGE = CURRENT_IMAGE + 1;
            }
        } else {
            if (CURRENT_IMAGE == IMAGE_FIRST) {
                CURRENT_IMAGE = IMAGE_LAST;
            } else {
                CURRENT_IMAGE = CURRENT_IMAGE - 1;
            }
        }
        return CURRENT_IMAGE;
    }

    public void onBackPressed() 
    {
        finish();
    }

    public void deleteDir(File dir) {
        if (dir != null && dir.isDirectory()) {
            try {
                File[] children = dir.listFiles();
                if (children.length > 0) {
                    for (int i = 0; i < children.length; i++) {
                        File[] temp = children[i].listFiles();
                        for (int x = 0; x < temp.length; x++) {
                            temp[x].delete();
                        }
                    }
                }
            } catch (Exception e) {
                Log.e("Cache", "failed cache clean");
            }
        }
    }

    public void downloadUrl(View v) {
        String url = "";
        // int url = 1;
        Log.e("Clicked1", "" + v.getTag());

    }

    @Override
    public void onClick(View v)
    {
        Intent iShare = new Intent(android.content.Intent.ACTION_SEND);
        iShare.putExtra(android.content.Intent.EXTRA_TEXT, getText());
        iShare.setType("text/plain");
        startActivity(Intent.createChooser(iShare, "select any from the list:"));
        /*finish();*/

    }

    public void setText(String sText)
    {
        this.m_sText = sText;
    }

    public String getText()
    {
        return m_sText;
    }

    @Override
    public void onDestroy()
    {
        if (speech != null) {
            speech.stop();
            speech.shutdown();
        }
        super.onDestroy();
    }

    @Override
    public void onInit(int status) 
    {
        if (status == TextToSpeech.SUCCESS)
        {
            int result = speech.setLanguage(Locale.US);
            if (result == TextToSpeech.LANG_MISSING_DATA
                    || result == TextToSpeech.LANG_NOT_SUPPORTED) {
                Log.e("TTS", "This Language is not supported");
            }
            else
            {
                bSpeakerButton.setEnabled(true);
                speak();
            }
        }
        else
        {
            Log.e("TTS", "Initilization Failed!");
        }
    }
}

Answer 1

要查看的代码很多，但我认为您不会在任何地方设置 speech 变量。您必须先创建一个 Speech 对象，然后才能调用它的方法。