2

Android应用程序在启动时不断崩溃。不过，在我看来一切都很好。

堆栈跟踪： 

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班级：

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>
4

2 回答 2

3

当您在清单中声明您的活动时，请尝试删除活动名称之前的包，这样您就android:name=".MainActivity"可以对其他活动进行同样的操作。

好吧，我的第一个答案是错误的。您的应用程序崩溃的原因是因为您已将主要活动声明为抽象删除它并且您的应用程序应该运行。

于 2013-01-24T21:53:52.037 回答
1

你的活动不应该是抽象的。

您还应该习惯于将函数包装在至少

try {
   /// Do some work
} catch (Throwable t) {
   Log.e(TAG, t.getMessage(), t);
}

在我的活动课程中，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。

编辑

而不是显示你的整个班级都被重写了。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);
    }
}
于 2013-01-24T22:12:05.693 回答