Question

我开发了一款通过短信发送用户位置的应用。当我开始构建它时没有错误，但是当它用实际手机进行测试时它会崩溃......它无法打开。

public class MainActivity extends AppCompatActivity {
EditText phone;
Button emergency;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    phone= (EditText) findViewById(R.id.number);

    emergency= (Button) findViewById(R.id.emergency);

    emergency.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            GPStracker g = new GPStracker(getApplicationContext());
            Location l = g.getLocation();
            if (l != null) {
                double lat = l.getLatitude();
                double lon = l.getLongitude();
                String message = "http://maps.google.com/maps?saddr=" + lat + "," + lon;
                String number = "number";
                SmsManager smsManager = SmsManager.getDefault();
                StringBuffer smsBody = new StringBuffer();
                smsBody.append(Uri.parse(message));
                android.telephony.SmsManager.getDefault().sendTextMessage(number, null, smsBody.toString(), null, null);
            }
        }
    });
}

此处也是我的GPS追踪类

public class GPStracker implements LocationListener {
    Context context;
    public GPStracker(Context c){
        context = c;
    }

    public Location getLocation(){

        LocationManager lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
        boolean isGPSEnabled = lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
        if (isGPSEnabled){
            lm.requestLocationUpdates(LocationManager.GPS_PROVIDER,5000,10,this);
            Location l = lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
            return l;
        }else{
            Toast.makeText(context,"Please enable GPS", Toast.LENGTH_LONG).show();
        }
        return null;
    }

    @Override
    public void onLocationChanged(Location location) {

    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {

    }

    @Override
    public void onProviderEnabled(String provider) {Intent intent = new Intent("android.location.GPS_ENABLED_CHANGE");
        intent.putExtra("enabled", true);

    }

    @Override
    public void onProviderDisabled(String provider) {
        Intent intent = new Intent("android.location.GPS_ENABLED_CHANGE");
        intent.putExtra("enabled", false);

    }
}

和我的宣言文件

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.research.sos.smshelpcaller">
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.WRITE_SETTINGS"/>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.SEND_SMS"/>
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.WRITE_SECURE_SETTINGS"/>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    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>
</application>

我已经尝试过一切，但我不知道我的代码中有什么错误，或者有些遗漏。

这里最后是LOGCAT的日志

04-03 13:55:56.472 31224-31224/com.research.sos.smshelpcaller E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.research.sos.smshelpcaller, PID: 31224
java.lang.NullPointerException: Attempt to get length of null array
    at android.os.Parcel.readException(Parcel.java:1546)
    at android.os.Parcel.readException(Parcel.java:1493)
    at com.android.internal.telephony.ISms$Stub$Proxy.sendText(ISms.java:1430)
    at android.telephony.SmsManager.sendTextMessage(SmsManager.java:320)
    at com.research.sos.smshelpcaller.MainActivity$1.onClick(MainActivity.java:37)
    at android.view.View.performClick(View.java:5052)
    at android.view.View$PerformClick.run(View.java:20162)
    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:5753)
    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:1405)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1200)

Answer 1

你的布局文件在哪里，在super.onCreate（savedInstanceState）;。

之后，将您的xml引用提供给activity

例如..

Function BatchRunMails()

Dim countrow As Integer, mailAddress As String, UniqueId As Integer
Dim Source As Object
Dim FixedFilePathName As String
Dim OverwriteIfFileExist As Boolean
Dim OpenPDFAfterPublish As Boolean
Dim FileFormatstr As String
Dim Fname As Variant
Dim ws As Worksheet

countrow = 340




While Sheets(BilledSheet).Cells(countrow, "A") <> ""
    mailAddress = Sheets(BilledSheet).Cells(countrow, "D")
    If mailAddress <> "" Then
        UniqueId = Sheets(BilledSheet).Cells(countrow, "A")
        Sheets(StatementSheet).Activate
        Sheets(StatementSheet).Cells(3, "O").Activate
        Sheets(StatementSheet).Cells(3, "O") = UniqueId
        Sheets(InvoiceSheet).Activate
        Sheets(InvoiceSheet).Cells(3, "M").Activate
        Sheets(InvoiceSheet).Cells(3, "M") = UniqueId

        If Dir(Environ("commonprogramfiles") & "\Microsoft Shared\OFFICE" _
         & Format(Val(Application.Version), "00") & "\EXP_PDF.DLL") <> ""   Then

Macro3
Macro2


            Set ws = ActiveSheet


           ActiveSheet.ExportAsFixedFormat Type:=xlTypePDF, _
           FileName:="C:\Users\c730057\Documents\02. Personal Folder\Saved PDF.pdf"










End If
End If

countrow = countrow + 1
Wend







End Function

Answer 2

根据您的日志，您尝试在Null Pointer上调用方法：

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.research.sos.smshelpcaller.MainActivity.onCreate(MainActivity.java:23)

这意味着，以下代码无法解析R.id.emergency资产。它根本无法找到它并且第一行被设置为null：

emergency= (Button) findViewById(R.id.emergency);
emergency.setOnClickListener(new View.OnClickListener() {...}

您应该检查您尝试使用的按钮的名称是否正确，是否没有拼写错误，或者是否存在资源文件（例如带有视图的xml）。

按下按钮时，用户位置发件人应用程序崩溃

2 个答案: