在android.text.Editable android.widget.EditText.getText（）在由顯示java.lang.NullPointerException致

Question

package com.mukesh; 

import android.content.Context; 
import android.content.res.TypedArray; 
import android.graphics.Color; 
import android.graphics.PorterDuff; 
import android.text.Editable; 
import android.text.TextUtils; 
import android.text.InputType; 
import android.text.TextWatcher; 
import android.util.AttributeSet; 
import android.view.LayoutInflater; 
import android.view.MotionEvent; 
import android.view.View; 
import android.util.Log; 
import android.view.inputmethod.EditorInfo; 
import android.view.inputmethod.InputMethodManager; 
import android.widget.EditText; 
import android.widget.LinearLayout; 

public class OtpView extends LinearLayout { 
    private EditText mOtpOneField, mOtpTwoField, mOtpThreeField, mOtpFourField, 
     mCurrentlyFocusedEditText; 

    public OtpView(Context context) { 
    super(context); 
    init(null); 
    } 

    public OtpView(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    init(attrs); 
    } 

    public OtpView(Context context, AttributeSet attrs, int defStyle) { 
    super(context, attrs, defStyle); 
    init(attrs); 
    } 

    private void init(AttributeSet attrs) { 
    TypedArray styles = getContext().obtainStyledAttributes(attrs, R.styleable.OtpView); 
    LayoutInflater mInflater = 
     (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
    mInflater.inflate(R.layout.otpview_layout, this); 
    mOtpOneField = (EditText) findViewById(R.id.otp_one_edit_text); 
    mOtpTwoField = (EditText) findViewById(R.id.otp_two_edit_text); 
    mOtpThreeField = (EditText) findViewById(R.id.otp_three_edit_text); 
    mOtpFourField = (EditText) findViewById(R.id.otp_four_edit_text); 
    styleEditTexts(styles); 
    styles.recycle(); 
    } 

    /** 
    * Get an instance of the present otp 
    */ 
    private String makeOTP(){ 
     StringBuilder stringBuilder=new StringBuilder(); 
     stringBuilder.append(mOtpOneField.getText().toString()); 
     stringBuilder.append(mOtpTwoField.getText().toString()); 
     stringBuilder.append(mOtpThreeField.getText().toString()); 
     stringBuilder.append(mOtpFourField.getText().toString()); 
     return stringBuilder.toString(); 
    } 

    /** 
    * Checks if all four fields have been filled 
    * @return length of OTP 
    */ 
    public boolean hasValidOTP(){ 
     return makeOTP().length()==4; 
    } 

    /** 
    * Returns the present otp entered by the user 
    * @return OTP 
    */ 
    public String getOTP(){ 
     return makeOTP(); 
    } 

    /** 
    * Used to set the OTP. More of cosmetic value than functional value 
    * @param otp Send the four digit otp 
    */ 
    public void setOTP(String otp){ 
     if(otp.length()!=4){ 
      Log.e("OTPView","Invalid otp param"); 
      return; 
     } 
     if(mOtpOneField.getInputType()== InputType.TYPE_CLASS_NUMBER 
       && !otp.matches("[0-9]+")){ 
      Log.e("OTPView","OTP doesn't match INPUT TYPE"); 
      return; 
     } 
     mOtpOneField.setText(otp.charAt(0)); 
     mOtpTwoField.setText(otp.charAt(1)); 
     mOtpThreeField.setText(otp.charAt(2)); 
     mOtpFourField.setText(otp.charAt(3)); 
    } 

    private void styleEditTexts(TypedArray styles) { 
    int textColor = styles.getColor(R.styleable.OtpView_android_textColor, Color.BLACK); 
    int backgroundColor = 
     styles.getColor(R.styleable.OtpView_text_background_color, Color.TRANSPARENT); 
    if (styles.getColor(R.styleable.OtpView_text_background_color, Color.TRANSPARENT) 
     != Color.TRANSPARENT) { 
     mOtpOneField.setBackgroundColor(backgroundColor); 
     mOtpTwoField.setBackgroundColor(backgroundColor); 
     mOtpThreeField.setBackgroundColor(backgroundColor); 
     mOtpFourField.setBackgroundColor(backgroundColor); 
    } else { 
     mOtpOneField.getBackground().mutate().setColorFilter(textColor, PorterDuff.Mode.SRC_ATOP); 
     mOtpTwoField.getBackground().mutate().setColorFilter(textColor, PorterDuff.Mode.SRC_ATOP); 
     mOtpThreeField.getBackground().mutate().setColorFilter(textColor, PorterDuff.Mode.SRC_ATOP); 
     mOtpFourField.getBackground().mutate().setColorFilter(textColor, PorterDuff.Mode.SRC_ATOP); 
    } 
    mOtpOneField.setTextColor(textColor); 
    mOtpTwoField.setTextColor(textColor); 
    mOtpThreeField.setTextColor(textColor); 
    mOtpFourField.setTextColor(textColor); 
    setEditTextInputStyle(styles); 
    } 

    private void setEditTextInputStyle(TypedArray styles) { 
    int inputType = 
     styles.getInt(R.styleable.OtpView_android_inputType, EditorInfo.TYPE_TEXT_VARIATION_NORMAL); 
    mOtpOneField.setInputType(inputType); 
    mOtpTwoField.setInputType(inputType); 
    mOtpThreeField.setInputType(inputType); 
    mOtpFourField.setInputType(inputType); 
    String text = styles.getString(R.styleable.OtpView_otp); 
    if (!TextUtils.isEmpty(text) && text.length() == 4) { 
     mOtpOneField.setText(String.valueOf(text.charAt(0))); 
     mOtpTwoField.setText(String.valueOf(text.charAt(1))); 
     mOtpThreeField.setText(String.valueOf(text.charAt(2))); 
     mOtpFourField.setText(String.valueOf(text.charAt(3))); 
    } 
    setFocusListener(); 
    setOnTextChangeListener(); 
    } 

    private void setFocusListener() { 
    View.OnFocusChangeListener onFocusChangeListener = new View.OnFocusChangeListener() { 
     @Override public void onFocusChange(View v, boolean hasFocus) { 
     mCurrentlyFocusedEditText = (EditText) v; 
     mCurrentlyFocusedEditText.setSelection(mCurrentlyFocusedEditText.getText().length()); 
     } 
    }; 
    mOtpOneField.setOnFocusChangeListener(onFocusChangeListener); 
    mOtpTwoField.setOnFocusChangeListener(onFocusChangeListener); 
    mOtpThreeField.setOnFocusChangeListener(onFocusChangeListener); 
    mOtpFourField.setOnFocusChangeListener(onFocusChangeListener); 
    } 

    public void disableKeypad() { 
    OnTouchListener touchListener = new OnTouchListener() { 
     @Override public boolean onTouch(View v, MotionEvent event) { 
     v.onTouchEvent(event); 
     InputMethodManager imm = 
      (InputMethodManager) v.getContext().getSystemService(Context.INPUT_METHOD_SERVICE); 
     if (imm != null) { 
      imm.hideSoftInputFromWindow(v.getWindowToken(), 0); 
     } 
     return true; 
     } 
    }; 
    mOtpOneField.setOnTouchListener(touchListener); 
    mOtpTwoField.setOnTouchListener(touchListener); 
    mOtpThreeField.setOnTouchListener(touchListener); 
    mOtpFourField.setOnTouchListener(touchListener); 
    } 

    public void enableKeypad() { 
    OnTouchListener touchListener = new OnTouchListener() { 
     @Override public boolean onTouch(View v, MotionEvent event) { 
     return false; 
     } 
    }; 
    mOtpOneField.setOnTouchListener(touchListener); 
    mOtpTwoField.setOnTouchListener(touchListener); 
    mOtpThreeField.setOnTouchListener(touchListener); 
    mOtpFourField.setOnTouchListener(touchListener); 
    } 

    public EditText getCurrentFoucusedEditText() { 
    return mCurrentlyFocusedEditText; 
    } 

    private void setOnTextChangeListener() { 
    TextWatcher textWatcher = new TextWatcher() { 
     @Override public void beforeTextChanged(CharSequence s, int start, int count, int after) { 

     } 

     @Override public void onTextChanged(CharSequence s, int start, int before, int count) { 
     } 

     @Override public void afterTextChanged(Editable s) { 
     if (mCurrentlyFocusedEditText.getText().length() >= 1 
      && mCurrentlyFocusedEditText != mOtpFourField) { 
      mCurrentlyFocusedEditText.focusSearch(View.FOCUS_RIGHT).requestFocus(); 
     } else if (mCurrentlyFocusedEditText.getText().length() >= 1 
      && mCurrentlyFocusedEditText == mOtpFourField) { 
      InputMethodManager imm = 
       (InputMethodManager) getContext().getSystemService(Context.INPUT_METHOD_SERVICE); 
      if (imm != null) { 
      // imm.hideSoftInputFromWindow(getWindowToken(), 0); 
      } 
     } else { 
      String currentValue = mCurrentlyFocusedEditText.getText().toString(); 
      if (currentValue.length() <= 0 && mCurrentlyFocusedEditText.getSelectionStart() <= 0) { 
      mCurrentlyFocusedEditText.focusSearch(View.FOCUS_LEFT).requestFocus(); 
      } 
     } 
     } 
    }; 
    mOtpOneField.addTextChangedListener(textWatcher); 
    mOtpTwoField.addTextChangedListener(textWatcher); 
    mOtpThreeField.addTextChangedListener(textWatcher); 
    mOtpFourField.addTextChangedListener(textWatcher); 
    } 

    public void simulateDeletePress() { 
    mCurrentlyFocusedEditText.setText(""); 
    } 
} 

得到錯誤得到空值：嘗試調用虛擬方法「android.text.Editable android.widget。 EditText.getText（）」上的com.mukesh.OtpView $ 4.afterTextChanged（OtpView.java:199）

Answer 1

空對象引用的ViewGroup延伸後，在XML添加的孩子被忽略，所以

@Override 
protected void onFinishInflate() { 
    super.onFinishInflate(); 

    //here either inflate from a separate xml layout and addView 
    //OR manually create Views dynamically addView 

}