java - 设置类实例时，我的 android 应用程序崩溃

Question

我是android编程的新手。我正在开发一个可以很好地打开并且几乎可以按照我想要的方式工作的应用程序。但我有一个问题，我不知道如何解决它。这就是问题所在：我正在用一个值填充 EditText，并且在我的 java 代码中，这个值将初始化我创建的一个对象。但这永远不会发生，因为任何初始化对象的尝试都会使我的应用程序崩溃。我在其中输入值以初始化对象的 editText 是名为 spotText 的那个。有人可以帮忙吗？这是 XML 代码：

<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:background="#000000"
    android:orientation="vertical"
    tools:context=".MainActivity" >

<ScrollView    
android:id="@+id/scroll"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:scrollbars="none">

<HorizontalScrollView 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">

<TableLayout
    android:id="@+id/TheTable"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:stretchColumns="0,1,2,3,4,5,6,7,8,9,10,11,12" >        

 <TableRow
     android:id="@+id/tbRow1"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content" >

  <TextView
    android:id="@+id/spot"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:paddingRight="10dp"
    android:text="@string/spot"
    android:textSize="10sp"
    android:gravity="center"
    android:textColor="@color/white" />

  <TextView
        android:id="@+id/div"               
        android:text="@string/div"
        android:gravity="center"
        android:textColor="@color/white"
        android:textSize="10sp" />      

    <TextView
        android:id="@+id/rate"
        android:text="@string/Rate"
        android:gravity="center"
        android:textColor="@color/white"
        android:textSize="10sp" />

    <CheckBox 
        android:id="@+id/smile"
        android:text="@string/UseSmile"             
        android:textColor="@color/white"
        android:textSize="10sp"/>

    <TextView
        android:id="@+id/ATM"
        android:text="@string/ATM"
        android:gravity="center"
        android:textColor="@color/white"
        android:textSize="10sp" />
</TableRow>

<TableRow
    android:id="@+id/tbRow2"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" >

    <EditText
        android:id="@+id/spotText"
        android:hint="@string/Spot"
        android:gravity="center"      
        android:inputType="numberSigned"
        android:textColor="@color/white"
        android:textSize="10sp" />

    <EditText
        android:id="@+id/divRate"
        android:hint="@string/divRate"
        android:gravity="center"    
        android:inputType="numberDecimal"
        android:textColor="@color/white"
        android:textSize="10sp" />

    <EditText
        android:id="@+id/IR"
        android:hint="@string/IRate"
        android:gravity="center"    
        android:inputType="numberDecimal"
        android:textColor="@color/white"
        android:textSize="10sp" />
    <EditText
        android:id="@+id/ATMVOL"
        android:hint="@string/ATM"
        android:layout_column="4"
        android:gravity="center"    
        android:inputType="numberDecimal"
        android:textColor="@color/white"
        android:textSize="10sp" />

</TableRow>        

            <TableRow
                android:id="@+id/tbRow3"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" >

                <TextView
                    android:id="@+id/product"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="10dp"
                    android:text="@string/product"
                    android:gravity="center"
                    android:textSize="10sp"
                    android:textColor="@color/white" />


                <TextView
                    android:id="@+id/strike"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="10dp"
                    android:text="@string/strike"
                    android:textSize="10sp"
                    android:gravity="center"
                    android:textColor="@color/white" />

                <TextView
                    android:id="@+id/maturity"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="10dp"
                    android:text="@string/maturity"
                    android:textSize="10sp"
                    android:gravity="center"
                    android:textColor="@color/white" />

                <TextView
                    android:id="@+id/vol"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="10dp"
                    android:textSize="10sp"
                    android:gravity="center"
                    android:text="@string/volatility"
                    android:textColor="@color/white" />

                <TextView
                    android:id="@+id/Qty"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="10dp"
                    android:textSize="10sp"
                    android:gravity="center"
                    android:text="@string/Quantity"
                    android:textColor="@color/white" />

                <TextView
                    android:id="@+id/price"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="15dp"
                    android:textSize="10sp"
                    android:gravity="center"
                    android:text="@string/price"
                    android:textColor="@color/white" />

                <TextView
                    android:id="@+id/delta"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="10dp"
                    android:text="@string/delta"
                    android:textSize="10sp"
                    android:gravity="center"
                    android:textColor="@color/white" />

                <TextView
                    android:id="@+id/gamma"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="10dp"
                    android:text="@string/gamma"
                    android:textSize="10sp"
                    android:gravity="center"
                    android:textColor="@color/white" />

                <TextView
                    android:id="@+id/theta"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="10dp"
                    android:text="@string/theta"
                    android:textSize="10sp"
                    android:gravity="center"
                    android:textColor="@color/white" />

                <TextView
                    android:id="@+id/vega"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="10dp"
                    android:text="@string/vega"
                    android:textSize="10sp"
                    android:gravity="center"
                    android:textColor="@color/white" />

                <TextView
                    android:id="@+id/vanna"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="10dp"
                    android:text="@string/vanna"
                    android:textSize="10sp"
                    android:gravity="center"
                    android:textColor="@color/white" />

                <TextView
                    android:id="@+id/vomma"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:paddingRight="10dp"
                    android:text="@string/vomma"
                    android:textSize="10sp"
                    android:gravity="center"
                    android:textColor="@color/white" />
            </TableRow>
            <TableRow
                android:id="@+id/tbRow4" >
                <Spinner 
                    android:id="@+id/spin1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:dropDownSelector="@string/Product"
                    android:prompt="@string/Product"
                    android:entries="@array/Array"
                    android:background="@color/SpinColor"
                    android:textSize="10sp"/>
                <EditText
                    android:id="@+id/K1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:hint="K"
                    android:gravity="center"
                    android:textSize="10sp"/>
                <EditText
                    android:id="@+id/T1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:hint="T"
                    android:gravity="center"
                    android:textSize="10sp"/>
                <EditText
                    android:id="@+id/Vol1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:hint="Vol"
                    android:gravity="center"
                    android:textSize="10sp"/>
                <EditText
                    android:id="@+id/Qty1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:hint="Qty"
                    android:gravity="center"
                    android:textSize="10sp"/>
                <TextView
                    android:id="@+id/Px1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:textSize="10sp"/>           
                <TextView
                    android:id="@+id/delta1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:textSize="10sp"/>
                <TextView
                    android:id="@+id/gamma1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:textSize="10sp"/>
                <TextView
                    android:id="@+id/theta1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:textSize="10sp"/>
                <TextView
                    android:id="@+id/vega1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:textSize="10sp"/>
                <TextView
                    android:id="@+id/vanna1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:textSize="10sp"/>
                <TextView
                    android:id="@+id/vomma1"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:textSize="10sp"/>
            </TableRow>

            <TableRow
                android:id="@+id/tbRow9">                
                 <Button 
                    android:id="@+id/delBtn"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textSize="10sp"
                    android:text="@string/delete"/>
                <Button 
                    android:id="@+id/addBtn"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textSize="10sp"
                    android:text="@string/Add"/>

            </TableRow>
        </TableLayout>

   </HorizontalScrollView>
</ScrollView>            

这是 MainActivity 类代码

    package com.example.lilpricer;

    import android.app.Activity;
    import android.os.Bundle;
    import android.text.Editable;
    import android.text.TextWatcher;
    import android.view.Menu;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.widget.Button;
    import android.widget.CheckBox;
    import android.widget.CompoundButton;
    import android.widget.CompoundButton.OnCheckedChangeListener;
    import android.widget.EditText;
    import android.widget.Spinner;
    import android.widget.TableRow;
    import android.widget.TextView;

    public class MainActivity extends Activity {

int nbRow = 1;

TableRow tb1 = null; TableRow tb2 = null; TableRow tb3 = null; TableRow tb4 = null;
TableRow tb5 = null; TableRow tb6 = null; TableRow tb7 = null; TableRow tb8 = null;
TableRow tb9 = null; 
TextView tvVol = null; TextView tvSpot;
EditText etSpot = null; EditText etDiv = null; EditText etIR = null; EditText etVol = null;
EditText etK1= null; EditText etK2= null; EditText etK3 = null; EditText etK4= null;
EditText etMat1= null; EditText etMat2= null; EditText etMat3 = null; EditText etMat4= null;
EditText etVol1= null; EditText etVol2= null; EditText etVol3 = null; EditText etVol4= null;
EditText etQty1= null; EditText etQty2= null; EditText etQty3 = null; EditText etQty4= null;
Spinner spin1 = null; Spinner spin2 = null; Spinner spin3 = null; Spinner spin4 = null;
Button Del = null; Button Add = null; Button Price = null;
CheckBox cbSmile = null;
Stock S=null; 
Future Fut1 = null; Future Fut2 = null; Future Fut3 = null; Future Fut4 = null;
Option Opt1 = null; Option Opt2 = null; Option Opt3 = null; Option Opt4 = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    setWidgetRef();


    tb5.setVisibility(View.INVISIBLE); tb6.setVisibility(View.INVISIBLE); tb7.setVisibility(View.INVISIBLE); 
    tvVol.setVisibility(View.INVISIBLE); etVol.setVisibility(View.INVISIBLE);       


    etSpot.addTextChangedListener(new TextWatcher() {
        double TheSpot= 0;          
        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            // TODO Auto-generated method stub
            TheSpot=Double.parseDouble(etSpot.getText().toString());                
            S.SetStock(TheSpot);
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {
            // TODO Auto-generated method stub

        }

        @Override
        public void afterTextChanged(Editable s) {
            // TODO Auto-generated method stub

        }
    });
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}



private void setWidgetRef()
    {
        tb1 = (TableRow) findViewById(R.id.tbRow1); tb2 = (TableRow) findViewById(R.id.tbRow2);
        tb3 = (TableRow) findViewById(R.id.tbRow3); tb4 = (TableRow) findViewById(R.id.tbRow4);
        tb5 = (TableRow) findViewById(R.id.tbRow5); tb6 = (TableRow) findViewById(R.id.tbRow6);
        tb7 = (TableRow) findViewById(R.id.tbRow7); tb8 = (TableRow) findViewById(R.id.tbRow8);
        tb9 = (TableRow) findViewById(R.id.tbRow9); 

        etSpot = (EditText) findViewById(R.id.spotText); etDiv=(EditText) findViewById(R.id.divRate); 
        etIR= (EditText) findViewById(R.id.IR); etVol = (EditText) findViewById(R.id.ATMVOL);
        etK1= (EditText) findViewById(R.id.K1); etK2= (EditText) findViewById(R.id.K2);
        etK3= (EditText) findViewById(R.id.K3); etK4= (EditText) findViewById(R.id.K4);
        etMat1 = (EditText) findViewById(R.id.T1);etMat2 = (EditText) findViewById(R.id.T2); 
        etMat3 = (EditText) findViewById(R.id.T3);etMat4 = (EditText) findViewById(R.id.T4);
        etVol1 =(EditText) findViewById(R.id.Vol1);etVol2 =(EditText) findViewById(R.id.Vol2);
        etVol3 =(EditText) findViewById(R.id.Vol3);etVol4 =(EditText) findViewById(R.id.Vol4);
        etQty1=(EditText)  findViewById(R.id.Qty1); etQty2=(EditText)  findViewById(R.id.Qty2); 
        etQty3=(EditText)  findViewById(R.id.Qty3); etQty4=(EditText)  findViewById(R.id.Qty4);

        tvVol = (TextView) findViewById(R.id.ATM); tvSpot = (TextView) findViewById(R.id.spot);

        Del = (Button) findViewById(R.id.delBtn); Add = (Button) findViewById(R.id.addBtn);
        Price = (Button) findViewById(R.id.priceBtn);

        cbSmile = (CheckBox) findViewById(R.id.smile);

        spin1 = (Spinner) findViewById(R.id.spin1);spin2 = (Spinner) findViewById(R.id.spin2);
        spin3 = (Spinner) findViewById(R.id.spin3);spin4 = (Spinner) findViewById(R.id.spin4);
    }
    }

这是我尝试初始化实例的类

    package com.example.lilpricer;

public class Stock {
private double S;   

Stock(double Price){
    S=Math.abs(Price);
}

Stock(){
    this.S=0;
}
public void SetStock(double price) {
    // TODO Auto-generated method stub
    S=Math.abs(price);
}
}

这是应用程序崩溃时的logcat。如您所见，它似乎是 EditText 中的 NullPointerException，我在其中输入了初始化对象 Stock 的值，但我不明白为什么会出现这样的错误，因为我在 java 中定义了一个 EditText 并将它与 EditText 链接在我的 XML 页面中，与我的对象（此处命名为 S）相同，它已被定义为全局变量，因此它存在。我显然在这里遗漏了一些东西，但我只是看不到它是什么。非常感谢您的帮助。

01-06 02:06:24.770: E/AndroidRuntime(5721): FATAL EXCEPTION: main
01-06 02:06:24.770: E/AndroidRuntime(5721): java.lang.NullPointerException
01-06 02:06:24.770: E/AndroidRuntime(5721):     at com.example.lilpricer.MainActivity$1.onTextChanged(MainActivity.java:144)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.widget.TextView.sendOnTextChanged(TextView.java:7092)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.widget.TextView.handleTextChanged(TextView.java:7151)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:8794)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.text.SpannableStringBuilder.sendTextChanged(SpannableStringBuilder.java:962)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:496)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:435)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:30)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.text.method.NumberKeyListener.onKeyDown(NumberKeyListener.java:121)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.widget.TextView.doKeyDown(TextView.java:5246)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.widget.TextView.onKeyDown(TextView.java:5065)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.KeyEvent.dispatch(KeyEvent.java:2609)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.View.dispatchKeyEvent(View.java:7198)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.widget.HorizontalScrollView.dispatchKeyEvent(HorizontalScrollView.java:332)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.widget.ScrollView.dispatchKeyEvent(ScrollView.java:353)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1359)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchKeyEvent(PhoneWindow.java:1920)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at com.android.internal.policy.impl.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1395)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.app.Activity.dispatchKeyEvent(Activity.java:2370)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1847)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.ViewRootImpl.deliverKeyEventPostIme(ViewRootImpl.java:3701)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.ViewRootImpl.handleImeFinishedEvent(ViewRootImpl.java:3651)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:2818)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.os.Looper.loop(Looper.java:137)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at android.app.ActivityThread.main(ActivityThread.java:5039)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at java.lang.reflect.Method.invokeNative(Native Method)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at java.lang.reflect.Method.invoke(Method.java:511)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-06 02:06:24.770: E/AndroidRuntime(5721):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

你从来没有实例化过这个类。在使用之前添加S=new Stock()或；S=new Stock(price)S