Android应用程序在启动时不断崩溃。 不过，我觉得一切都很好。
堆栈追踪：
01-24 21:23:41.417: I/Process(767): Sending signal. PID: 767 SIG: 9
01-24 21:41:36.316: W/Trace(890): Unexpected value from nativeGetEnabledTags: 0
01-24 21:41:36.485: W/Trace(890): Unexpected value from nativeGetEnabledTags: 0
01-24 21:41:36.515: W/Trace(890): Unexpected value from nativeGetEnabledTags: 0
01-24 21:41:36.515: D/dalvikvm(890): newInstance failed: p0 i0 [0 a1
01-24 21:41:36.515: D/AndroidRuntime(890): Shutting down VM
01-24 21:41:36.515: W/dalvikvm(890): threadid=1: thread exiting with uncaught exception (group=0x40a70930)
01-24 21:41:36.635: E/AndroidRuntime(890): FATAL EXCEPTION: main
01-24 21:41:36.635: E/AndroidRuntime(890): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.bmisummative/com.example.bmisummative.MainActivity}: java.lang.InstantiationException: can't instantiate class com.example.bmisummative.MainActivity
01-24 21:41:36.635: E/AndroidRuntime(890): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2106)
01-24 21:41:36.635: E/AndroidRuntime(890): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
01-24 21:41:36.635: E/AndroidRuntime(890): at android.app.ActivityThread.access$600(ActivityThread.java:141)
01-24 21:41:36.635: E/AndroidRuntime(890): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
01-24 21:41:36.635: E/AndroidRuntime(890): at android.os.Handler.dispatchMessage(Handler.java:99)
01-24 21:41:36.635: E/AndroidRuntime(890): at android.os.Looper.loop(Looper.java:137)
01-24 21:41:36.635: E/AndroidRuntime(890): at android.app.ActivityThread.main(ActivityThread.java:5039)
01-24 21:41:36.635: E/AndroidRuntime(890): at java.lang.reflect.Method.invokeNative(Native Method)
01-24 21:41:36.635: E/AndroidRuntime(890): at java.lang.reflect.Method.invoke(Method.java:511)
01-24 21:41:36.635: E/AndroidRuntime(890): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-24 21:41:36.635: E/AndroidRuntime(890): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-24 21:41:36.635: E/AndroidRuntime(890): at dalvik.system.NativeStart.main(Native Method)
01-24 21:41:36.635: E/AndroidRuntime(890): Caused by: java.lang.InstantiationException: can't instantiate class com.example.bmisummative.MainActivity
01-24 21:41:36.635: E/AndroidRuntime(890): at java.lang.Class.newInstanceImpl(Native Method)
01-24 21:41:36.635: E/AndroidRuntime(890): at java.lang.Class.newInstance(Class.java:1319)
01-24 21:41:36.635: E/AndroidRuntime(890): at android.app.Instrumentation.newActivity(Instrumentation.java:1054)
01-24 21:41:36.635: E/AndroidRuntime(890): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2097)
01-24 21:41:36.635: E/AndroidRuntime(890): ... 11 more
01-24 21:46:36.745: I/Process(890): Sending signal. PID: 890 SIG: 9
MainActivity上课：
package com.example.bmisummative;
import android.app.Activity;
import android.content.DialogInterface;
import android.view.View.OnClickListener;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public abstract class MainActivity extends Activity implements OnClickListener {
/** Called when the activity is first created. */
Button btn,btn1,btn2;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn = (Button) findViewById(R.id.buttonBMI);
btn.setOnClickListener(this);
btn1 = (Button) findViewById(R.id.buttonGain);
btn1.setOnClickListener(this);
btn2 = (Button) findViewById(R.id.buttonLoss);
btn2.setOnClickListener(this);
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.buttonBMI) {
startActivity(new Intent(this, MainActivity.class));
}
if (v.getId() == R.id.buttonGain) {
startActivity(new Intent(this, weightgain.class));
}
if (v.getId() == R.id.buttonLoss) {
startActivity(new Intent(this, weightgain.class));
}
}
}
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
tools:context=".StartingPoint"
android:background="@drawable/grunge">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Main Menu"
android:textSize="45dp"
android:layout_gravity="center"
android:gravity="center"
android:textColor="#FFFFFF"
android:id="@+id/tvDisplay"/>
<Button
android:id="@+id/buttonBMI"
android:layout_width="250dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="BMI Calculator"
android:textSize="20dp" />
<Button
android:id="@+id/buttonLoss"
android:layout_width="250dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Weight Loss Workouts"
android:textSize="20dp" />
<Button
android:id="@+id/buttonGain"
android:layout_width="250dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Muscle Gain Workouts"
android:textSize="20dp" />
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.bmisummative"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.bmisummative.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.example.bmiworking.calculator"
android:label="@string/app_name" >
</activity>
<activity
android:name="com.example.bmiworking.weightgain"
android:label="@string/app_name" >
</activity>
<activity
android:name="com.example.bmiworking.weightloss"
android:label="@string/app_name" >
</activity>
</application>
</manifest>
答案 0 :(得分：3)
当您在清单中声明您的活动时，请尝试在活动名称前删除该包，以便获得android:name=".MainActivity"并对其他活动执行相同操作。
好的，我的第一个回答是错误的。您的应用程序崩溃的原因是您已将主要活动声明为抽象删除，并且您的应用应该运行。
答案 1 :(得分：1)
您的活动不应该是抽象的。
您还应该习惯于至少
包装您的功能try {
/// Do some work
} catch (Throwable t) {
Log.e(TAG, t.getMessage(), t);
}
在我的活动类中，我将TAG定义为：
public static final String TAG = "NameMeSomethingUnique";
将字符串的值更改为通常的活动名称。
修改
而不是重写整个班级。我只是为try / catch修改onCreate并将TAG常量添加为类成员。您可以以相同的方式将try / catch块添加到其他方法中。
public class MainActivity extends Activity implements OnClickListener { // REMOVED abstract keyword - EJN
/** Called when the activity is first created. */
Button btn,btn1,btn2;
private static final String TAG = "MainActivity"; // Used to make logging easier - EJN
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
try { // Wrapped to trap any possible exceptions so we don't just crash - EJN
setContentView(R.layout.activity_main);
btn = (Button) findViewById(R.id.buttonBMI);
btn.setOnClickListener(this);
btn1 = (Button) findViewById(R.id.buttonGain);
btn1.setOnClickListener(this);
btn2 = (Button) findViewById(R.id.buttonLoss);
btn2.setOnClickListener(this);
} catch (Throwable t) {
Log.e(TAG, t.getMessage(), t);
}
}