从另一个类

Question

我是Java和Android开发的新手。我正在为儿童开发一个应用程序，在Java部分包含一些类。其中一个类用于交换名为ColorCustomSwipeAdapter的页面，还有另一个用于将文本转换为包含名为ReadName的方法的speakOut语音的类，问题在我尝试时开始通过speakOut类调用方法ColorCustomSwipeAdapter。它抛出NPE并且应用程序崩溃。

以下是代码：

ColorCustomSwipeAdapter.java

package com.example.ibrahim.toddlerssmartbook;

import android.content.Context;
import android.speech.tts.TextToSpeech;
import android.support.v4.view.PagerAdapter;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;

import java.util.Locale;

 /**
    * Created by Ibrahim on 3/19/2016.
 */
public class ColorCustomSwipeAdapter extends PagerAdapter {

ReadName sayName=new ReadName() ;
private int[] image_resource = {R.drawable.red,R.drawable.green,R.drawable.blue,R.drawable.pink,R.drawable.gray ,R.drawable.yellow,R.drawable.brown,
           R.drawable.black,R.drawable.purple,R.drawable.orange,R.drawable.white};
private String[] color_name=   {"Red","Green","Blue","Pink","Gray","Yellow","Brown","Black","Purple","Orange","White"};
 private Context ctx;
  private LayoutInflater layoutInflater;
public ColorCustomSwipeAdapter(MainActivity ctx){this.ctx=ctx;}
@Override

public int getCount() {
    return image_resources.length;
}

@Override
public boolean isViewFromObject(View view, Object object) {
    return (view==(LinearLayout)object);
}

@Override
public Object instantiateItem(ViewGroup container, int position) {

    layoutInflater= (LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
      View    item_view=layoutInflater.inflate(R.layout.swipe_layout,container,false);
    ImageView imageView=(ImageView)item_view.findViewById(R.id.image_view);
    TextView textView=(TextView)item_view.findViewById(R.id.name);
    imageView.setImageResource(image_resources[position]);
    textView.setText(color_name[position]);

    sayName.speakOut(color_name[position]);//The ERROR IS HERE

    container.addView(item_view);
    return item_view;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((LinearLayout)object);
    }
}

Readname.java

package com.example.ibrahim.toddlerssmartbook;

import android.content.Context;
import android.speech.tts.TextToSpeech;
import android.support.v7.app.AppCompatActivity;
import android.widget.Toast;

import java.io.IOException;
import java.util.Locale;

/**
   * Created by Ibrahim on 4/7/2016.
*/
public class ReadName extends AppCompatActivity {
private int result;

public ReadName() {
   result=0;
}

 TextToSpeech  ttsObject=new TextToSpeech(this,new              TextToSpeech.OnInitListener(){
   @Override
 public void onInit(int status){
 if(status==TextToSpeech.SUCCESS){
result = ttsObject.setLanguage(Locale.US);
}else{
Toast.makeText(getApplicationContext(),"Feature not supported in your    device.",Toast.LENGTH_SHORT).show();
   }}
  });
  public void speakOut(String name){

 if (result == TextToSpeech.LANG_NOT_SUPPORTED || result ==    TextToSpeech.LANG_MISSING_DATA) {
      Toast.makeText(getApplicationContext(), "Feature not supported in your    device.", Toast.LENGTH_SHORT).show();
   } else {
      ttsObject.speak(name, TextToSpeech.QUEUE_FLUSH, null);
   }
  }
   @Override
   public void onDestroy() {

    if (ttsObject != null) {
        ttsObject.stop();
        ttsObject.shutdown();
    }
    super.onDestroy();
 }
}