switch語句不工作

Question

我想簡化我的代碼，對變量在可能降低，並且我一直在logcat中收到此錯誤時，我的應用程序運行，並且應用程序關閉：

02-14 00:13:10.279 32478-32478/com.example.chris.sunil_gupta W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x415998e0) 
02-14 00:13:10.289 32478-32478/com.example.chris.sunil_gupta E/AndroidRuntime﹕ FATAL EXCEPTION: main 
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.chris.sunil_gupta/com.example.chris.sunil_gupta.MainActivity}: android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 500 

有人能告訴我我的代碼有什麼問題嗎？此代碼工作完美，但我想我可以簡化一點：

package com.example.chris.sunil_gupta; 

import java.util.ArrayList; 
import java.util.Date; 
import java.util.List; 

import android.app.Activity; 
import android.content.Context; 
import android.database.Cursor; 
import android.os.Bundle; 
import android.provider.CallLog; 
import android.widget.ListView; 

public class MainActivity extends Activity { 



    private List <CallData>list = new ArrayList<CallData>(); 
    private Context context=null; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 

     ListView listview; 

     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 



     context=this; 

     listview=(ListView)findViewById(R.id.ListView_CallData); 

     getCallDetails(); 
     CustomAdapter adapter = new CustomAdapter(MainActivity.this, list); 
     listview.setAdapter(adapter); 
    } 

    public void getCallDetails() 
    { 


     //  cursor1 gets all the items in the calllog and arranges them from newest call down 
     Cursor cursor1 = getContentResolver().query(
       CallLog.Calls.CONTENT_URI, null, null, null, CallLog.Calls.DATE + " DESC"); 

//looks like all the cell values in the calllog database are integers 
     int number = cursor1.getColumnIndex(CallLog.Calls.NUMBER); 
     int type = cursor1.getColumnIndex(CallLog.Calls.TYPE); 
     int date = cursor1.getColumnIndex(CallLog.Calls.DATE); 
     int duration = cursor1.getColumnIndex(CallLog.Calls.DURATION); 

//declare some new variables here; we're going to convert the integers into these 
     String callType; 
     String phoneNumber; 
     String callDate; 
     String callDuration; 
     Date callDateTime; 

//go through all the rows in the db and convert the values to strings or whatever 
     while (cursor1.moveToNext()) 
     { 

      phoneNumber = cursor1.getString(number); 
      callType = cursor1.getString(type); 
      callDate = cursor1.getString(date); 

      callDateTime = new Date(Long.valueOf(callDate)); 

      callDuration = cursor1.getString(duration); 

//   the string cType will give us text of either outgoing, incoming or missed 
      String cType = null; 


      int cTypeCode = Integer.parseInt(callType); 

      switch(cTypeCode) 
      { 
       case CallLog.Calls.OUTGOING_TYPE: 
        cType = "OUTGOING"; 
        break; 

       case CallLog.Calls.INCOMING_TYPE: 
        cType= "INCOMING"; 
        break; 

       case CallLog.Calls.MISSED_TYPE: 
        cType = "MISSED"; 
        break; 
      } 

      CallData calldata=new CallData(cType, phoneNumber, callDateTime, callDuration); 
      list.add(calldata); 
     } 

     cursor1.close(); 
    } 
} 

此代碼給我的錯誤。基本上，我已經改變了：

int type = cursor1.getColumnIndex(CallLog.Calls.TYPE); 

到

String type = cursor1.getString(cursor1.getColumnIndex(CallLog.Calls.TYPE)); 

和

取代cTypeCode變量有：

switch (Integer.parseInt(type)) 

下面是給我的錯誤代碼：

package com.example.chris.sunil_gupta; 

import java.util.ArrayList; 
import java.util.Date; 
import java.util.List; 

import android.app.Activity; 
import android.content.Context; 
import android.database.Cursor; 
import android.os.Bundle; 
import android.provider.CallLog; 
import android.widget.ListView; 

public class MainActivity extends Activity { 



    private List <CallData>list = new ArrayList<CallData>(); 
    private Context context=null; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 

     ListView listview; 

     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     context=this; 

     listview=(ListView)findViewById(R.id.ListView_CallData); 

     getCallDetails(); 
     CustomAdapter adapter = new CustomAdapter(MainActivity.this, list); 
     listview.setAdapter(adapter); 
    } 

    public void getCallDetails() 
    { 


     //  cursor1 gets all the items in the calllog and arranges them from newest call down 
     Cursor cursor1 = getContentResolver().query(
       CallLog.Calls.CONTENT_URI, null, null, null, CallLog.Calls.DATE + " DESC"); 

//looks like all the cell values in the calllog database are integers 
     int number = cursor1.getColumnIndex(CallLog.Calls.NUMBER); 
//  int type = cursor1.getColumnIndex(CallLog.Calls.TYPE); 
     String type = cursor1.getString(cursor1.getColumnIndex(CallLog.Calls.TYPE)); 
     int date = cursor1.getColumnIndex(CallLog.Calls.DATE); 
     int duration = cursor1.getColumnIndex(CallLog.Calls.DURATION); 


//declare some new variables here; we're going to convert the integers into these 

     String phoneNumber; 
     String callDate; 
     String callDuration; 
     Date callDateTime; 

//go through all the rows in the db and convert the values to strings or whatever 
     while (cursor1.moveToNext()) 
     { 

      phoneNumber = cursor1.getString(number); 

      callDate = cursor1.getString(date); 

      callDateTime = new Date(Long.valueOf(callDate)); 

      callDuration = cursor1.getString(duration); 

//   the string cType will give us text of either outgoing, incoming or missed 
      String cType = null; 

      switch (Integer.parseInt(type)) 
      { 
       case CallLog.Calls.OUTGOING_TYPE: 
        cType = "OUTGOING"; 
        break; 

       case CallLog.Calls.INCOMING_TYPE: 
        cType= "INCOMING"; 
        break; 

       case CallLog.Calls.MISSED_TYPE: 
        cType = "MISSED"; 
        break; 
      } 

      CallData calldata=new CallData(cType, phoneNumber, callDateTime, callDuration); 
      list.add(calldata); 
     } 

     cursor1.close(); 
    } 
} 

Answer 1

String type = cursor1.getString(cursor1.getColumnIndex(CallLog.Calls.TYPE));

此行在while循環之外。當光標位於無效位置（-1）時，它將嘗試讀取列的值，因爲尚未調用moveToNext()。恢復查找列索引並提取while循環內的調用類型。

此外，你應該使用cursor.getInt()代替：

int callType = cursor.getInt(typeIndex); 
switch (callType) { 
    // etc 
}