앱의 다음 활동 페이지로 이동하려고하면 앱이 작동을 멈 춥니 다.

Question

꽤 기본적인 6-7 활동 앱을 만들고있어 정말 간단하게 유지하려고합니다. 성공적으로 네 가지 인스턴스를 추가했습니다. 앱의 하단에서 '다음'을 누르면 앱의 다음 활동으로 이동합니다. 그러나, 나는 붙어있어 계속하는 법을 알 수 없다. 디버깅을 시도했지만 오류 메시지의 의미를 파악할 수 없습니다. 당신의 도움을 주셔서 감사합니다.

로그 캣에서 오류 메시지 :

java.lang.IllegalStateException: Could not execute method for android:onClick 
                       at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293) 
                       at android.view.View.performClick(View.java:4785) 
                       at android.view.View$PerformClick.run(View.java:19884) 
                       at android.os.Handler.handleCallback(Handler.java:739) 
                       at android.os.Handler.dispatchMessage(Handler.java:95) 
                       at android.os.Looper.loop(Looper.java:135) 
                       at android.app.ActivityThread.main(ActivityThread.java:5343) 
                       at java.lang.reflect.Method.invoke(Native Method) 
                       at java.lang.reflect.Method.invoke(Method.java:372) 
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905) 
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700) 
                       Caused by: java.lang.reflect.InvocationTargetException 
                       at java.lang.reflect.Method.invoke(Native Method) 
                       at java.lang.reflect.Method.invoke(Method.java:372) 
                       at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
                       at android.view.View.performClick(View.java:4785)  
                       at android.view.View$PerformClick.run(View.java:19884)  
                       at android.os.Handler.handleCallback(Handler.java:739)  
                       at android.os.Handler.dispatchMessage(Handler.java:95)  
                       at android.os.Looper.loop(Looper.java:135)  
                       at android.app.ActivityThread.main(ActivityThread.java:5343)  
                       at java.lang.reflect.Method.invoke(Native Method)  
                       at java.lang.reflect.Method.invoke(Method.java:372)  
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905)  
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700)  
                       Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.CharSequence android.widget.TextView.getText()' on a null object reference 
                       at com.example.android.budgeit10.expenses.fourthNext(expenses.java:86) 
                       at java.lang.reflect.Method.invoke(Native Method)  
                       at java.lang.reflect.Method.invoke(Method.java:372)  
                       at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)  
                       at android.view.View.performClick(View.java:4785)  
                       at android.view.View$PerformClick.run(View.java:19884)  
                       at android.os.Handler.handleCallback(Handler.java:739)  
                       at android.os.Handler.dispatchMessage(Handler.java:95)  
                       at android.os.Looper.loop(Looper.java:135)  
                       at android.app.ActivityThread.main(ActivityThread.java:5343)  
                       at java.lang.reflect.Method.invoke(Native Method)  
                       at java.lang.reflect.Method.invoke(Method.java:372)  
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905)  
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700) 

  

JAVA :

<LinearLayout 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" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    tools:context="com.example.android.budgeit10.incomePage"> 

    <TextView 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:gravity="center" 
     android:text="MONTHLY EXPENSES" 
     android:textSize="24dp" /> 

    <LinearLayout 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:orientation="horizontal"> 

     <TextView 
      android:id="@+id/totalMonthlyIncome" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:paddingBottom="16dp" 
      android:paddingTop="16dp" 
      android:text="Enter Monthly Income" 
      android:textSize="22dp" 
      android:textStyle="bold" /> 


     <EditText 
      android:id="@+id/monthlyIncome" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:hint="@string/income_on_expenses" 
      android:inputType="phone" 
      android:paddingLeft="16dp" 
      android:paddingRight="16dp" 
      android:textSize="16dp" /> 

    </LinearLayout> 

    <LinearLayout 
     android:layout_width="match_parent" 
     android:layout_height="2dp" 
     android:background="#2E7D32" /> 

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


     <TextView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:padding="8dp" 
      android:text="HOUSING" 
      android:textSize="22dp" 
      android:textStyle="bold" /> 

     <EditText 
      android:id="@+id/housingExpense" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_weight="1" 
      android:hint="@string/housing" 
      android:inputType="phone" 
      android:paddingLeft="16dp" 
      android:paddingRight="16dp" /> 

    </LinearLayout> 


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

     <TextView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:padding="8dp" 
      android:paddingTop="16dp" 
      android:text="FOOD" 
      android:textSize="22dp" 
      android:textStyle="bold" /> 

     <EditText 
      android:id="@+id/foodExpense" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_weight="1" 
      android:hint="@string/food" 
      android:inputType="phone" 
      android:paddingLeft="16dp" 
      android:paddingRight="16dp" /> 

    </LinearLayout> 

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

     <TextView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:padding="8dp" 
      android:paddingTop="16dp" 
      android:text="TRANSPORTATION" 
      android:textSize="22dp" 
      android:textStyle="bold" /> 

     <EditText 
      android:id="@+id/transportExpense" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_weight="1" 
      android:hint="@string/transport" 
      android:inputType="phone" 
      android:paddingLeft="16dp" 
      android:paddingRight="16dp" /> 
    </LinearLayout> 

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

     <TextView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:padding="8dp" 
      android:paddingTop="16dp" 
      android:text="EVERYTHING ELSE" 
      android:textSize="22dp" 
      android:textStyle="bold" /> 

     <EditText 
      android:id="@+id/otherExpense" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_weight="1" 
      android:hint="@string/other" 
      android:inputType="phone" 
      android:paddingLeft="16dp" 
      android:paddingRight="16dp" /> 

    </LinearLayout> 

    <LinearLayout 
     android:layout_width="match_parent" 
     android:layout_height="2dp" 
     android:background="#2E7D32" /> 

    <LinearLayout 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:orientation="horizontal" 
     android:paddingTop="16dp"> 

     <Button 
      android:id="@+id/expensesButton" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_weight="1" 
      android:background="#C8E6C9" 
      android:onClick="submitOrder" 
      android:padding="16dp" 
      android:text="TOTAL EXPENSES" 
      android:textSize="16dp" 
      android:textStyle="bold" /> 

     <TextView 
      android:id="@+id/totalMonthlyExpenses" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:hint="@string/monthly_expenses" 
      android:inputType="phone" 
      android:paddingLeft="16dp" 
      android:paddingRight="16dp" 
      android:textSize="16dp" /> 
    </LinearLayout> 

    <LinearLayout 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:orientation="horizontal"> 

     <TextView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:paddingTop="8dp" 
      android:text="Extra $ : " 
      android:textSize="24dp" 
      android:textStyle="bold" /> 

     <TextView 
      android:id="@+id/extra_cash" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:hint="@string/extra_cash" 
      android:inputType="phone" 
      android:paddingLeft="16dp" 
      android:paddingRight="16dp" 
      android:textSize="16dp" /> 
    </LinearLayout> 

    <RelativeLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:orientation="horizontal"> 

     <Button 
      android:id="@+id/fourthNext" 
      android:layout_width="match_parent" 
      android:layout_height="100dp" 
      android:layout_alignParentBottom="true" 
      android:background="#C8E6C9" 
      android:onClick="fourthNext" 
      android:text="NEXT" 
      android:textSize="34dp"> 

     </Button> 
    </RelativeLayout> 


</LinearLayout> 

매니페스트 :

<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
package="com.example.android.budgeit10"> 

<application 
    android:allowBackup="true" 
    android:icon="@mipmap/ic_launcher" 
    android:label="@string/app_name" 
    android:supportsRtl="true" 
    android:theme="@style/AppTheme"> 
    <activity android:name=".MainActivity"> 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 

      <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 
    <activity android:name=".PageTwo" /> 
    <activity android:name=".incomePage" /> 
    <activity android:name=".expenses" /> 
    <activity android:name=".Goals" /> 
</application> 

버튼에서

 package com.example.android.budgeit10; 

    import android.content.Intent; 
    import android.support.v7.app.AppCompatActivity; 
    import android.os.Bundle; 
    import android.text.TextUtils; 
    import android.view.View; 
    import android.widget.Button; 
    import android.widget.EditText; 
    import android.widget.TextView; 

    public class expenses extends AppCompatActivity { 

     AppCompatActivity appCompatActivity; 
     EditText housingExpense; 
     EditText foodExpense; 
     EditText transportExpense; 
     EditText otherExpense; 
     Button expensesButton; 
     TextView addExpenses; 
     EditText income; 

     double housing, food, transport, other, sum; 


     @Override 
     public void onCreate(Bundle savedInstanceState) { 

      super.onCreate(savedInstanceState); 
      setContentView(R.layout.activity_expenses); 
      housingExpense = (EditText) findViewById(R.id.housingExpense); 
      foodExpense = (EditText) findViewById(R.id.foodExpense); 
      transportExpense = (EditText) findViewById(R.id.transportExpense); 
      otherExpense = (EditText) findViewById(R.id.otherExpense); 
      expensesButton = (Button) findViewById(R.id.expensesButton); 
      addExpenses = (TextView) findViewById(R.id.totalMonthlyExpenses); 
      income = (EditText) findViewById(R.id.monthlyIncome); 


      expensesButton.setOnClickListener(new View.OnClickListener() { 
       @Override 
       public void onClick(View view) { 
        housing = Double.parseDouble(housingExpense.getText().toString()); 
        try { 
         Double.parseDouble(housingExpense.getText().toString()); 
        } catch (NumberFormatException nfe) { 
        } 
        food = Double.parseDouble(foodExpense.getText().toString()); 
        transport = Double.parseDouble(transportExpense.getText().toString()); 
        other = Double.parseDouble(otherExpense.getText().toString()); 
        sum = housing + food + transport + other; 
        addExpenses.setText(Double.toString(sum)); 

       } 
      }); 

      expensesButton.setOnClickListener(new View.OnClickListener() { 
       @Override 
       public void onClick(View view) { 


        if (TextUtils.isEmpty(housingExpense.getText().toString()) || 
          TextUtils.isEmpty(foodExpense.getText().toString()) || 
          TextUtils.isEmpty(otherExpense.getText().toString()) || 
          TextUtils.isEmpty(transportExpense.getText().toString())) { 

         addExpenses.setText("Please fill all fields."); // if any of the fields is empty, add nothing to textview 

        } else { 
         Double housing = Double.parseDouble(housingExpense.getText().toString()); 
         Double food = Double.parseDouble(foodExpense.getText().toString()); 
         Double transport = Double.parseDouble(transportExpense.getText().toString()); 
         Double other = Double.parseDouble(otherExpense.getText().toString()); 
         Double sum = housing + food + transport + other; 
         addExpenses.setText(Double.toString(sum)); 
        } 
       } 
      }); 
     } 
     public void fourthNext(View view) { 
      Intent intent = new Intent(this, Goals.class); 
      TextView textView = (TextView) findViewById(R.id.totalMonthlyIncome); 

      String income = textView.getText().toString(); 
      startActivity(intent); 

     } 

XML

Answer 1

XML 레이아웃에 'totalMonthlyIncome'이라는 ID를 가진 TextView가 있어야합니다. (자바 코드에 따르면) 거기에 있는지 확인하면 문제가 해결됩니다. java.lang.NullPointerException이 :

는 "에 의한 시도는 com.example.android에서 널 객체 참조

에 ') java.lang.CharSequence android.widget.TextView.getText ('가상 메소드를 호출 .budgeit10.expenses.fourthNext (expenses.java:86) "

는 로그 캣 에러에 따른 expenses.java 인 - 라인 86