我知道已经有很多关于如何解决致命异常的条目，但没有一个能解决我的问题。我正在开发一个非常简单的计算器，它有九个按钮、一个编辑文本和一个文本视图。它的全部目的是简单地输入一个数字，点击一个带有另一个数字的按钮，然后这些产品将出现在文本视图中。
<RelativeLayout 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" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginTop="16dp"
android:text="@string/number" />
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView1"
android:layout_centerHorizontal="true"
android:layout_marginTop="16dp"
android:ems="10"
android:inputType="numberDecimal" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/editText1"
android:layout_marginLeft="16dp"
android:layout_marginTop="23dp"
android:text="@string/s1" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/button1"
android:layout_alignBottom="@+id/button1"
android:layout_centerHorizontal="true"
android:text="@string/s2" />
<Button
android:id="@+id/button3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/button2"
android:layout_alignBottom="@+id/button2"
android:layout_alignRight="@+id/textView1"
android:text="@string/s3" />
<Button
android:id="@+id/button4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button1"
android:layout_below="@+id/button1"
android:layout_marginTop="16dp"
android:text="@string/s4" />
<Button
android:id="@+id/button5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/button4"
android:layout_alignBottom="@+id/button4"
android:layout_alignLeft="@+id/button2"
android:text="@string/s5" />
<Button
android:id="@+id/button6"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/button5"
android:layout_alignBottom="@+id/button5"
android:layout_alignLeft="@+id/button3"
android:text="@string/s6" />
<Button
android:id="@+id/button7"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button4"
android:layout_below="@+id/button4"
android:layout_marginTop="22dp"
android:text="@string/s7" />
<Button
android:id="@+id/button8"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/button7"
android:layout_alignBottom="@+id/button7"
android:layout_alignLeft="@+id/button5"
android:text="@string/s8" />
<Button
android:id="@+id/button9"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/button8"
android:layout_alignBottom="@+id/button8"
android:layout_alignLeft="@+id/button6"
android:text="@string/s9" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button8"
android:layout_below="@+id/button8"
android:layout_marginTop="70dp"
/>
</RelativeLayout>
我终于解决了所有的问题，或者我是这么想的，但是现在当我尝试运行程序时，它甚至在加载之前就意外停止了：
11-10 11:50:13.198: E/AndroidRuntime(451): FATAL EXCEPTION: main
11-10 11:50:13.198: E/AndroidRuntime(451): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.deitel.multiplicationtables/com.deitel.multiplicationtables.Main}: java.lang.InstantiationException: com.deitel.multiplicationtables.Main
11-10 11:50:13.198: E/AndroidRuntime(451): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1569)
11-10 11:50:13.198: E/AndroidRuntime(451): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
11-10 11:50:13.198: E/AndroidRuntime(451): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
11-10 11:50:13.198: E/AndroidRuntime(451): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
11-10 11:50:13.198: E/AndroidRuntime(451): at android.os.Handler.dispatchMessage(Handler.java:99)
11-10 11:50:13.198: E/AndroidRuntime(451): at android.os.Looper.loop(Looper.java:123)
11-10 11:50:13.198: E/AndroidRuntime(451): at android.app.ActivityThread.main(ActivityThread.java:3683)
11-10 11:50:13.198: E/AndroidRuntime(451): at java.lang.reflect.Method.invokeNative(Native Method)
11-10 11:50:13.198: E/AndroidRuntime(451): at java.lang.reflect.Method.invoke(Method.java:507)
11-10 11:50:13.198: E/AndroidRuntime(451): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-10 11:50:13.198: E/AndroidRuntime(451): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
11-10 11:50:13.198: E/AndroidRuntime(451): at dalvik.system.NativeStart.main(Native Method)
11-10 11:50:13.198: E/AndroidRuntime(451): Caused by: java.lang.InstantiationException: com.deitel.multiplicationtables.Main
11-10 11:50:13.198: E/AndroidRuntime(451): at java.lang.Class.newInstanceImpl(Native Method)
11-10 11:50:13.198: E/AndroidRuntime(451): at java.lang.Class.newInstance(Class.java:1409)
11-10 11:50:13.198: E/AndroidRuntime(451): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
11-10 11:50:13.198: E/AndroidRuntime(451): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1561)
11-10 11:50:13.198: E/AndroidRuntime(451): ... 11 more
11-10 11:55:13.367: I/Process(451): Sending signal. PID: 451 SIG: 9
我知道这可能是一些小事，但我找不到我搞砸的地方。任何帮助表示赞赏！
显现：
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.deitel.multiplicationtables"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".Main"
android:label="@string/title_activity_main" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
JAVA代码：
package com.deitel.multiplicationtables;
import android.os.Bundle;
import android.app.Activity;
import android.widget.Button;
import android.widget.TextView;
import android.widget.EditText;
import android.view.View;
//Implements the listener for an onclick event (implements View.onClickListener)
public abstract class Main extends Activity implements View.OnClickListener{
// creates a button
private Button bone, btwo, bthree, bfour, bfive, bsix, bseven, beight, bnine;
// Called when the activity is first created.
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//assigns the resource id of 1 - 9 to each button.
bone = (Button) findViewById(R.id.button1);
btwo = (Button) findViewById(R.id.button2);
bthree = (Button) findViewById(R.id.button3);
bfour = (Button) findViewById(R.id.button4);
bfive = (Button) findViewById(R.id.button5);
bsix = (Button) findViewById(R.id.button6);
bseven = (Button) findViewById(R.id.button7);
beight = (Button) findViewById(R.id.button8);
bnine = (Button) findViewById(R.id.button9);
//Adds the buttons to the onclicklistener
bone.setOnClickListener(this);
btwo.setOnClickListener(this);
bthree.setOnClickListener(this);
bfour.setOnClickListener(this);
bfive.setOnClickListener(this);
bsix.setOnClickListener(this);
bseven.setOnClickListener(this);
beight.setOnClickListener(this);
bnine.setOnClickListener(this);
}
//creates a method (or action) for when the button is clicked.
public void onclick(View view)
{
//Makes a variable for the entered number
Double amount = 0.0;
Double product = 0.0;
Double variable = 0.0;
// constants
final double one = 1.0;
final double two = 2.0;
final double three = 3.0;
final double four = 4.0;
final double five = 5.0;
final double six = 6.0;
final double seven = 7.0;
final double eight = 8.0;
final double nine = 9.0;
if (view.getId() == R.id.button1)
{
variable = one;
}
if (view.getId() == R.id.button2)
{
variable = two;
}
if (view.getId()== R.id.button3)
{
variable = three;
}
if (view.getId() == R.id.button4)
{
variable = four;
}
if (view.getId() == R.id.button5)
{
variable = five;
}
if (view.getId()== R.id.button6)
{
variable = six;
}
if (view.getId() == R.id.button7)
{
variable = seven;
}
if (view.getId() == R.id.button8)
{
variable = eight;
}
if (view.getId()== R.id.button9)
{
variable = nine;
}
//creates an editext and assigns the resource id of the xml edittext.
EditText number = (EditText)findViewById(R.id.editText1);
//Receives the input from the edittext, converts it to a double (number).
amount = Double.parseDouble(number.getText().toString());
//Calculates the product
product = variable * amount;
//Creates a textview object, assigns the xml r.id, and then changes the text to report the amount.
TextView t = (TextView)findViewById(R.id.textView2);
t.setText("Your product is: " + product);
}
}