我正在尝试制作一个简单的联系人列表应用。我尝试编辑我的联系人通过单击电话列表到活动结果，编辑后我按下保存按钮它通过在此行抛出“id = null”给我空指针异常
long rowId=Long.parseLong(DBHandler.Key_ID)
在活动结果（...）功能中。在调试过程中，当我在列表中单击联系人进行编辑时，它会获取id，但是当我保存编辑部分时，它会将id赋予null。请帮帮我。
这是源代码：
public class WebpreneurActivity extends ListActivity {
private static final int CONTACT_CREATE = 0;
private static final int CONTACT_EDIT = 1;
public static long id1;
//select the second one, Android view menu
private static final int INSERT_ID = Menu.FIRST;
private static final int DELETE_ID = Menu.FIRST + 1;
private DBHandler dbHelper;
private Cursor c;
ImageButton imageButton;
public static long rowId;
@Override
protected void onCreate(Bundle savedInstanceState) {
Log.d("database1" ,"0");
Log.d("Your Location4", "ok4:");
super.onCreate(savedInstanceState);
Log.d("database1" ,"1");
setContentView(R.layout.activity_webpreneur);
Log.d("database1" ,"2");
dbHelper = new DBHandler(this);
Log.d("database1" ,"3");
dbHelper.open();
fillData();
//dbHelper.open();
//addListenerOnButton();
//dbHelper.addContact();
imageButton = (ImageButton) findViewById(R.id.imageButton1);
Log.d("database1" ,"button");
imageButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
Log.d("database1" ,"b4");
Intent i = new Intent(getApplicationContext(), ContactEdit.class);
startActivityForResult(i, CONTACT_CREATE);
Log.d("database1" ,"button3");
//fillData();
}
});
//dbHelper.close();
}
@SuppressWarnings("deprecation")
public void fillData() {
Log.d("Your Location4", "ok6:");
c = dbHelper.fetchAllRows();
Log.d("Your Location4", "ok8:");
//startManagingCursor(c);
Log.d("Your Location4", "ok2:");
NoIdCursorWrapper nc = new NoIdCursorWrapper(c, DBHandler.Key_ID);
ListAdapter adapter = new SimpleCursorAdapter(this, R.layout.contact_row, nc, new String[] { DBHandler.Key_Name, DBHandler.Key_Phone }, new int[] { R.id.name, R.id.phonenumber });
setListAdapter(adapter);
}
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
Intent i = new Intent(this, ContactEdit.class);
i.putExtra(DBHandler.Key_ID, c.getLong(c.getColumnIndex(DBHandler.Key_ID)));
i.putExtra(DBHandler.Key_Name, c.getString(c.getColumnIndex(DBHandler.Key_Name)));
i.putExtra(DBHandler.Key_Address, c.getString(c.getColumnIndex(DBHandler.Key_Address)));
i.putExtra(DBHandler.Key_Phone, c.getString(c.getColumnIndex(DBHandler.Key_Phone)));
i.putExtra(DBHandler.Key_Website, c.getString(c.getColumnIndex(DBHandler.Key_Home)));
startActivityForResult(i, CONTACT_EDIT);
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK) {
String name = data.getStringExtra(DBHandler.Key_Name);
String address = data.getStringExtra(DBHandler.Key_Address);
String mobile = data.getStringExtra(DBHandler.Key_Phone);
String home = data.getStringExtra(DBHandler.Key_Home);
//String id = data.getStringExtra(DBHandler.Key_ID);
switch (requestCode) {
case CONTACT_CREATE:
Log.d("Your Location4", "jj:");
dbHelper.createRow(name, address, mobile, home);
Log.d("Your Location4" , "ok90:");
fillData();
break;
case CONTACT_EDIT:
//String id = data.getStringExtra(DBHandler.Key_ID);
long rowId=Long.parseLong(DBHandler.Key_ID); ////Giving null pointer exception at this point
Log.d("Your Location4" , "ok9b:");
if (rowId != (Long)null){
dbHelper.updateRow(rowId, name, address, mobile, home);
}
fillData();
break;
}
}
}
}
这是我的log cat /// [注意：正确格式化logcat]
01-29 16:12:13.617: E/AndroidRuntime(26320): FATAL EXCEPTION: main
01-29 16:12:13.617: E/AndroidRuntime(26320): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { (has extras) }} to activity {com.webpreneur_contactlist/com.webpreneur_contactlist.WebpreneurActivity}: java.lang.NumberFormatException: ID
01-29 16:12:13.617: E/AndroidRuntime(26320): at android.app.ActivityThread.deliverResults(ActivityThread.java:2553)
01-29 16:12:13.617: E/AndroidRuntime(26320): at android.app.ActivityThread.handleSendResult(ActivityThread.java:2595)
01-29 16:12:13.617: E/AndroidRuntime(26320): at android.app.ActivityThread.access$2000(ActivityThread.java:121)
01-29 16:12:13.617: E/AndroidRuntime(26320): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:973)
01-29 16:12:13.617: E/AndroidRuntime(26320): at android.os.Handler.dispatchMessage(Handler.java:99)
01-29 16:12:13.617: E/AndroidRuntime(26320): at android.os.Looper.loop(Looper.java:138)
01-29 16:12:13.617: E/AndroidRuntime(26320): at android.app.ActivityThread.main(ActivityThread.java:3701)
01-29 16:12:13.617: E/AndroidRuntime(26320): at java.lang.reflect.Method.invokeNative(Native Method)
01-29 16:12:13.617: E/AndroidRuntime(26320): at java.lang.reflect.Method.invoke(Method.java:507)
01-29 16:12:13.617: E/AndroidRuntime(26320): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:878)
01-29 16:12:13.617: E/AndroidRuntime(26320): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:636)
01-29 16:12:13.617: E/AndroidRuntime(26320): at dalvik.system.NativeStart.main(Native Method)
01-29 16:12:13.617: E/AndroidRuntime(26320): Caused by: java.lang.NumberFormatException: ID
01-29 16:12:13.617: E/AndroidRuntime(26320): at java.lang.Long.parse(Long.java:353)
01-29 16:12:13.617: E/AndroidRuntime(26320): at java.lang.Long.parseLong(Long.java:344)
01-29 16:12:13.617: E/AndroidRuntime(26320): at java.lang.Long.parseLong(Long.java:311)
01-29 16:12:13.617: E/AndroidRuntime(26320): at com.webpreneur_contactlist.WebpreneurActivity.onActivityResult(WebpreneurActivity.java:129)
01-29 16:12:13.617: E/AndroidRuntime(26320): at android.app.Activity.dispatchActivityResult(Activity.java:3908)
01-29 16:12:13.617: E/AndroidRuntime(26320): at android.app.ActivityThread.deliverResults(ActivityThread.java:2549)
答案 0 :(得分：3)
更改为：
long rowId=data.getLongExtra(DBHandler.Key_ID,0);
之后：
if (rowId != 0){
dbHelper.updateRow(rowId, name, address, mobile, home);
}
答案 1 :(得分：0)
用try-catch包裹并处理异常
long rowId;
try {
rowId=Long.parseLong(DBHandler.Key_ID);
} catch (NumberFormatException ex) {
//Handle exception!
//f.ex. rowId = -1;
}