Androidの電卓がボタンのクリックでクラッシュする

Question

こんにちは私はAndroidの電卓アプリで最近作業していますが、ほとんど終了しましたが、クリックすると数字やその他の演算子がクラッシュすると問題が発生します。その後、アプリケーション全体がクラッシュします。下記のリストコード：

activity_main.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
android:id="@+id/calculator_holder" 
xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:orientation="vertical" 
tools:context="com.example.stins.calculator.MainActivity"> 

<TextView 
    android:id="@+id/formula" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:layout_weight="2.1" 
    android:fontFamily="sans-serif-light" 
    android:gravity="right|bottom" 
    android:maxLines="1" 
    android:paddingLeft="@dimen/activity_margin" 
    android:paddingRight="@dimen/activity_margin" 
    android:textSize="@dimen/formula_text_size"/> 

<TextView 
    android:id="@+id/result" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:layout_weight="1.8" 
    android:fontFamily="sans-serif-light" 
    android:gravity="center_vertical|right" 
    android:maxLines="1" 
    android:paddingLeft="@dimen/activity_margin" 
    android:paddingRight="@dimen/activity_margin" 
    android:text="0" 
    android:textSize="@dimen/display_text_size"/> 

<LinearLayout 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:layout_weight="2" 
    android:orientation="horizontal"> 

    <Button 
     android:id="@+id/btn_modulo" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="mod" 
     android:textAllCaps="false" 
     android:textSize="@dimen/mod_text_size"/> 

    <Button 
     android:id="@+id/btn_power" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="^"/> 

    <Button 
     android:id="@+id/btn_root" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="√"/> 

    <Button 
     android:id="@+id/btn_clear" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="C" 
     android:longClickable="true"/> 

    <Button 
     android:id="@+id/btn_reset" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="AC" 
     android:visibility="gone"/> 
</LinearLayout> 

<LinearLayout 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:layout_weight="2" 
    android:orientation="horizontal"> 

    <Button 
     android:id="@+id/btn_7" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="7" 
     /> 

    <Button 
     android:id="@+id/btn_8" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="8"/> 

    <Button 
     android:id="@+id/btn_9" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="9"/> 

    <Button 
     android:id="@+id/btn_divide" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="÷"/> 
</LinearLayout> 

<LinearLayout 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:layout_weight="2" 
    android:orientation="horizontal"> 

    <Button 
     android:id="@+id/btn_4" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="4"/> 

    <Button 
     android:id="@+id/btn_5" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="5"/> 

    <Button 
     android:id="@+id/btn_6" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="6"/> 

    <Button 
     android:id="@+id/btn_multiply" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="*"/> 
</LinearLayout> 

<LinearLayout 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:layout_weight="2" 
    android:orientation="horizontal"> 

    <Button 
     android:id="@+id/btn_1" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="1"/> 

    <Button 
     android:id="@+id/btn_2" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="2"/> 

    <Button 
     android:id="@+id/btn_3" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="3"/> 

    <Button 
     android:id="@+id/btn_minus" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="-"/> 
</LinearLayout> 

<LinearLayout 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:layout_weight="2" 
    android:orientation="horizontal"> 

    <Button 
     android:id="@+id/btn_0" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="0"/> 

    <Button 
     android:id="@+id/btn_decimal" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="."/> 

    <Button 
     android:id="@+id/btn_equals" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="="/> 

    <Button 
     android:id="@+id/btn_plus" 
     style="@style/MyButton" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_weight="1" 
     android:text="+"/> 
</LinearLayout> 
</LinearLayout> 

MainActivity.java

package com.example.stins.calculator; 

import android.content.ClipData; 
import android.content.ClipboardManager; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.TextView; 
import android.widget.Toast; 

import com.example.stins.calculator.Calculator; 
import com.example.stins.calculator.CalculatorImpl; 
import com.example.stins.calculator.Config; 
import com.example.stins.calculator.Constants; 
import com.example.stins.calculator.Formatter; 
import com.example.stins.calculator.Utils; 

import butterknife.BindView; 
import butterknife.ButterKnife; 
import butterknife.OnClick; 
import butterknife.OnLongClick; 
import me.grantland.widget.AutofitHelper; 

public class MainActivity extends SimpleActivity implements Calculator { 
@BindView(R.id.result) 
TextView mResult; 
@BindView(R.id.formula) 
TextView mFormula; 

private static CalculatorImpl mCalc; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    ButterKnife.bind(this); 

    CalculatorImpl calc = new CalculatorImpl(this); 
    AutofitHelper.create(mResult); 
    AutofitHelper.create(mFormula); 
} 

@OnClick(R.id.btn_plus) 
public void plusClicked() { 
    mCalc.handleOperation(Constants.PLUS); 
} 

@OnClick(R.id.btn_minus) 
public void minusClicked() { 
    mCalc.handleOperation(Constants.MINUS); 
} 

@OnClick(R.id.btn_multiply) 
public void multiplyClicked() { 
    mCalc.handleOperation(Constants.MULTIPLY); 
} 

@OnClick(R.id.btn_divide) 
public void divideClicked() { 
    mCalc.handleOperation(Constants.DIVIDE); 
} 

@OnClick(R.id.btn_modulo) 
public void moduloClicked() { 
    mCalc.handleOperation(Constants.MODULO); 
} 

@OnClick(R.id.btn_power) 
public void powerClicked() { 
    mCalc.handleOperation(Constants.POWER); 
} 

@OnClick(R.id.btn_root) 
public void rootClicked() { 
    mCalc.handleOperation(Constants.ROOT); 
} 

@OnClick(R.id.btn_clear) 
public void clearClicked() { 
    mCalc.handleClear(); 
} 

@OnLongClick(R.id.btn_clear) 
public boolean clearLongClicked() { 
    mCalc.handleReset(); 
    return true; 
} 

@OnClick(R.id.btn_equals) 
public void equalsClicked() { 
    mCalc.handleEquals(); 
} 

@OnClick({R.id.btn_decimal, R.id.btn_0, R.id.btn_1, R.id.btn_2, R.id.btn_3, R.id.btn_4, R.id.btn_5, R.id.btn_6, R.id.btn_7, R.id.btn_8, 
     R.id.btn_9}) 
public void numpadClick(View view) { 
    //Toast.makeText(this, "click handler called", Toast.LENGTH_SHORT).show(); 
    numpadClicked(view.getId()); 
} 

public void numpadClicked(int id) { 
    mCalc.numpadClicked(id); 
} 


@Override 
public void setValue(String value) { 
    mResult.setText(value); 
} 

@Override 
public void setValueDouble(double d) { 
    mCalc.setValue(Formatter.doubleToString(d)); 
    mCalc.setLastKey(Constants.DIGIT); 
} 

public void setFormula(String value) { 
    mFormula.setText(value); 
} 

public CalculatorImpl getCalc() { 
    return mCalc; 
} 
} 

CalculatorImpl.java

package com.example.stins.calculator; 

public class CalculatorImpl { 
private String mDisplayedValue; 
private String mDisplayedFormula; 
private String mLastKey; 
private String mLastOperation; 
private Calculator mCallback; 

private boolean mIsFirstOperation; 
private boolean mResetValue; 
private double mBaseValue; 
private double mSecondValue; 

public CalculatorImpl(Calculator calculator) { 
    mCallback = calculator; 
    resetValues(); 
    setValue("0"); 
    setFormula(""); 
} 

public CalculatorImpl(Calculator calculatorInterface, String value) { 
    mCallback = calculatorInterface; 
    resetValues(); 
    mDisplayedValue = value; 
    setFormula(""); 
} 

private void resetValueIfNeeded() { 
    if (mResetValue) 
     mDisplayedValue = "0"; 

    mResetValue = false; 
} 

private void resetValues() { 
    mBaseValue = 0; 
    mSecondValue = 0; 
    mResetValue = false; 
    mLastKey = ""; 
    mLastOperation = ""; 
    mDisplayedValue = ""; 
    mDisplayedFormula = ""; 
    mIsFirstOperation = true; 
} 

public void setValue(String value) { 
    mCallback.setValue(value); 
    mDisplayedValue = value; 
} 

private void setFormula(String value) { 
    mCallback.setFormula(value); 
    mDisplayedFormula = value; 
} 

private void updateFormula() { 
    final String first = Formatter.doubleToString(mBaseValue); 
    final String second = Formatter.doubleToString(mSecondValue); 
    final String sign = getSign(mLastOperation); 

    if (sign.equals("√")) { 
     setFormula(sign + first); 
    } else if (!sign.isEmpty()) { 
     setFormula(first + sign + second); 
    } 
} 

public void setLastKey(String mLastKey) { 
    this.mLastKey = mLastKey; 
} 

public void addDigit(int number) { 
    final String currentValue = getDisplayedNumber(); 
    final String newValue = formatString(currentValue + number); 
    setValue(newValue); 
} 

private String formatString(String str) { 
    // if the number contains a decimal, do not try removing the leading zero anymore, nor add group separator 
    // it would prevent writing values like 1.02 
    if (str.contains(".")) 
     return str; 

    final double doubleValue = Formatter.stringToDouble(str); 
    return Formatter.doubleToString(doubleValue); 
} 

private void updateResult(double value) { 
    setValue(Formatter.doubleToString(value)); 
    mBaseValue = value; 
} 

public String getDisplayedNumber() { 
    return mDisplayedValue; 
} 

public double getDisplayedNumberAsDouble() { 
    return Formatter.stringToDouble(getDisplayedNumber()); 
} 

public String getDisplayedFormula() { 
    return mDisplayedFormula; 
} 

public void handleResult() { 
    mSecondValue = getDisplayedNumberAsDouble(); 
    calculateResult(); 
    mBaseValue = getDisplayedNumberAsDouble(); 
} 

public void calculateResult() { 
    if (!mIsFirstOperation) 
     updateFormula(); 

    switch (mLastOperation) { 
     case Constants.PLUS: 
      updateResult(mBaseValue + mSecondValue); 
      break; 
     case Constants.MINUS: 
      updateResult(mBaseValue - mSecondValue); 
      break; 
     case Constants.MULTIPLY: 
      updateResult(mBaseValue * mSecondValue); 
      break; 
     case Constants.DIVIDE: 
      divideNumbers(); 
      break; 
     case Constants.MODULO: 
      moduloNumbers(); 
      break; 
     case Constants.POWER: 
      powerNumbers(); 
      break; 
     case Constants.ROOT: 
      updateResult(Math.sqrt(mBaseValue)); 
      break; 
     default: 
      break; 
    } 
    mIsFirstOperation = false; 
} 

private void divideNumbers() { 
    double resultValue = 0; 
    if (mSecondValue != 0) 
     resultValue = mBaseValue/mSecondValue; 

    updateResult(resultValue); 
} 

private void moduloNumbers() { 
    double resultValue = 0; 
    if (mSecondValue != 0) 
     resultValue = mBaseValue % mSecondValue; 

    updateResult(resultValue); 
} 

private void powerNumbers() { 
    double resultValue = Math.pow(mBaseValue, mSecondValue); 
    if (Double.isInfinite(resultValue) || Double.isNaN(resultValue)) 
     resultValue = 0; 
    updateResult(resultValue); 
} 

public void handleOperation(String operation) { 
    if (mLastKey.equals(Constants.DIGIT)) 
     handleResult(); 

    mResetValue = true; 
    mLastKey = operation; 
    mLastOperation = operation; 

    if (operation.equals(Constants.ROOT)) 
     calculateResult(); 
} 

public void handleClear() { 
    final String oldValue = getDisplayedNumber(); 
    String newValue = "0"; 
    final int len = oldValue.length(); 
    int minLen = 1; 
    if (oldValue.contains("-")) 
     minLen++; 

    if (len > minLen) 
     newValue = oldValue.substring(0, len - 1); 

    newValue = newValue.replaceAll("\\.$", ""); 
    newValue = formatString(newValue); 
    setValue(newValue); 
    mBaseValue = Formatter.stringToDouble(newValue); 
} 

public void handleReset() { 
    resetValues(); 
    setValue("0"); 
    setFormula(""); 
} 

public void handleEquals() { 
    if (mLastKey.equals(Constants.EQUALS)) 
     calculateResult(); 

    if (!mLastKey.equals(Constants.DIGIT)) 
     return; 

    mSecondValue = getDisplayedNumberAsDouble(); 
    calculateResult(); 
    mLastKey = Constants.EQUALS; 
} 

public void decimalClicked() { 
    String value = getDisplayedNumber(); 
    if (!value.contains(".")) 
     value += "."; 
    setValue(value); 
} 

public void zeroClicked() { 
    String value = getDisplayedNumber(); 
    if (!value.equals("0")) 
     addDigit(0); 
} 

private String getSign(String lastOperation) { 
    switch (lastOperation) { 
     case Constants.PLUS: 
      return "+"; 
     case Constants.MINUS: 
      return "-"; 
     case Constants.MULTIPLY: 
      return "*"; 
     case Constants.DIVIDE: 
      return "/"; 
     case Constants.MODULO: 
      return "%"; 
     case Constants.POWER: 
      return "^"; 
     case Constants.ROOT: 
      return "√"; 
    } 
    return ""; 
} 

public void numpadClicked(int id) { 
    if (mLastKey.equals(Constants.EQUALS)) 
     mLastOperation = Constants.EQUALS; 
    mLastKey = Constants.DIGIT; 
    resetValueIfNeeded(); 

    switch (id) { 
     case R.id.btn_decimal: 
      decimalClicked(); 
      break; 
     case R.id.btn_0: 
      zeroClicked(); 
      break; 
     case R.id.btn_1: 
      addDigit(1); 
      break; 
     case R.id.btn_2: 
      addDigit(2); 
      break; 
     case R.id.btn_3: 
      addDigit(3); 
      break; 
     case R.id.btn_4: 
      addDigit(4); 
      break; 
     case R.id.btn_5: 
      addDigit(5); 
      break; 
     case R.id.btn_6: 
      addDigit(6); 
      break; 
     case R.id.btn_7: 
      addDigit(7); 
      break; 
     case R.id.btn_8: 
      addDigit(8); 
      break; 
     case R.id.btn_9: 
      addDigit(9); 
      break; 
     default: 
      break; 
    } 
} 
} 

Logcat

02-11 20:18:59.116 6438-6438/com.example.stins.calculator E/AndroidRuntime: FATAL EXCEPTION: main 
                      Process: com.example.stins.calculator, PID: 6438 
                      java.lang.NullPointerException: Attempt to invoke virtual method 'void com.example.stins.calculator.CalculatorImpl.numpadClicked(int)' on a null object reference 
                       at com.example.stins.calculator.MainActivity.numpadClicked(MainActivity.java:105) 
                       at com.example.stins.calculator.MainActivity.numpadClick(MainActivity.java:101) 
                       at com.example.stins.calculator.MainActivity_ViewBinding$16.doClick(MainActivity_ViewBinding.java:192) 
                       at butterknife.internal.DebouncingOnClickListener.onClick(DebouncingOnClickListener.java:22) 
                       at android.view.View.performClick(View.java:5198) 
                       at android.view.View$PerformClick.run(View.java:21147) 
                       at android.os.Handler.handleCallback(Handler.java:739) 
                       at android.os.Handler.dispatchMessage(Handler.java:95) 
                       at android.os.Looper.loop(Looper.java:148) 
                       at android.app.ActivityThread.main(ActivityThread.java:5417) 
                       at java.lang.reflect.Method.invoke(Native Method) 
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

私はプログラムがクラッシュする原因を見つけることができません。誰かが何かを見ますか？私はすべての助けに感謝します！

Answer 1

この行削除：

CalculatorImpl calc = new CalculatorImpl(this); 

をしてと交換してください：

mCalc = new CalculatorImpl(this);