需要關於onClick和意圖的幫助

Question

我正在工作，並且基於記事本教程開發了一個應用程序...在教程中，您點擊listview中的一個記錄，然後您將被編輯顯示相應的信息，然後使你的改變選擇確認..並被帶回到主。

我現在添加了第二個活動到應用程序「聯繫人」，當你點擊列表視圖中的一個筆記，你被聯繫到相應的信息顯示包括一個按鈕.......... ..你點擊按鈕，並採取編輯.........這是我的問題彈出其醜陋的頭。當我點擊按鈕一個空白的屏幕和一個強制關閉彈出........

這裏是從主要帶你聯繫的代碼....這個作品的信息顯示

protected void onListItemClick(ListView l, View v, int position, long id) { 
    super.onListItemClick(l, v, position, id); 
    Intent i = new Intent(this, Contact.class); 
    i.putExtra(NotesDbAdapter.KEY_ROWID, id); 
    startActivityForResult(i, ACTIVITY_EDIT); 
} 

這是從接觸到編輯的代碼.....這給了我錯誤，我確定它與「intent.putExtra（NotesDbAdapter.KEY_ROWID，id）;」需要重新編碼用的onClick工作相比onListitemClick ........我想的ID沒有被經過

public void onClick(View v) { 
String id = null; 
switch (v.getId()) { 
case R.id.admin: // doStuff 
    Intent intent = new Intent(this, Contact.class); 
    intent.putExtra(NotesDbAdapter.KEY_ROWID, id); 
    startActivity(intent); 
    break; 

有人能告訴我如何從一個按鈕，這樣做????

這裏是主，聯繫人和編輯代碼..........如果你需要它.......感謝

Main.class

public class Main extends ListActivity { 
private static final int ACTIVITY_CREATE=0; 
private static final int ACTIVITY_EDIT=1; 

private static final int INSERT_ID = Menu.FIRST; 
private static final int DELETE_ID = Menu.FIRST + 1; 
private static final int ABOUT = Menu.FIRST + 2; 
private static final int TESTBUTTON = Menu.FIRST + 3; 
private static final int CONTACT_ID = Menu.FIRST + 4; 
private static final int CANCEL_ID = Menu.FIRST + 5; 

private NotesDbAdapter mDbHelper; 

/** Called when the activity is first created. */ 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
    mDbHelper = new NotesDbAdapter(this); 
    mDbHelper.open(); 
    fillData(); 
    registerForContextMenu(getListView()); 
} 

private void fillData() { 
    Cursor notesCursor = mDbHelper.fetchAllNotes(); 
    startManagingCursor(notesCursor); 

    // Create an array to specify the fields we want to display in the list (only TITLE) 
    String[] from = new String[]{NotesDbAdapter.KEY_NAME, NotesDbAdapter.KEY_RANK}; 


    // and an array of the fields we want to bind those fields to (in this case just text1) 
    int[] to = new int[]{R.id.text1, R.id.text2}; 

    // Now create a simple cursor adapter and set it to display 
    SimpleCursorAdapter notes = 
     new SimpleCursorAdapter(this, R.layout.mainlistrow, notesCursor, from, to); 
    setListAdapter(notes); 
} 

@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    super.onCreateOptionsMenu(menu); 
    menu.add(0, INSERT_ID, 0, R.string.menu_insert); 
    menu.add(0, ABOUT, 0, R.string.menu_about); 
    menu.add(0, TESTBUTTON, 0, R.string.menu_test); 
    return true; 
} 

@Override 
public boolean onMenuItemSelected(int featureId, MenuItem item) { 
    switch(item.getItemId()) { 
     case INSERT_ID: 
      createNote(); 
      return true; 
     case ABOUT:   
      menuabout();   
      return true; 
     case TESTBUTTON:   
      menutest();   
      return true;  
    } 

    return super.onMenuItemSelected(featureId, item); 
} 

@Override 
public void onCreateContextMenu(ContextMenu menu, View v, 
     ContextMenuInfo menuInfo) { 
    super.onCreateContextMenu(menu, v, menuInfo); 
    menu.add(0, CONTACT_ID, 0, R.string.menu_contact); 
    menu.add(0, DELETE_ID, 0, R.string.menu_delete); 
    menu.add(0, CANCEL_ID, 0, R.string.menu_cancel); 

} 

@Override 
public boolean onContextItemSelected(MenuItem item) { 
    switch(item.getItemId()) { 
     case DELETE_ID: 
      AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo(); 
      mDbHelper.deleteNote(info.id); 
      fillData(); 
      return true; 
     case CONTACT_ID: 
      contact(); 
      return true; 
    } 
    return super.onContextItemSelected(item); 
} 

private void menutest() { 
    Intent i = new Intent(this, Newmain.class); 
    startActivityForResult(i, ACTIVITY_CREATE); 
    Log.i(this.toString(), "menu test"); 
} 

private void contact() { 
    Intent i = new Intent(this, Contact.class); 
    startActivityForResult(i, ACTIVITY_CREATE); 
    Log.i(this.toString(), "menu contact"); 
}  

private void createNote() { 
    Intent i = new Intent(this, Admin.class); 
    startActivityForResult(i, ACTIVITY_CREATE); 
} 

public void menuabout() { 
    final Dialog dialog = new Dialog(Main.this); 
    dialog.setContentView(R.layout.about); 
    dialog.setTitle("About NCO Leaders Book");  
    dialog.setCancelable(true); 
    Button button = (Button) dialog.findViewById(R.id.AboutButton); 
    button.setOnClickListener(new OnClickListener() { 

    @Override 
    public void onClick(View v) { 
     dialog.dismiss(); 
    } 
       }); 
       //now that the dialog is set up, it's time to show it  
       dialog.show(); 
} 


@Override 
protected void onListItemClick(ListView l, View v, int position, long id) { 
    super.onListItemClick(l, v, position, id); 
    Intent i = new Intent(this, Contact.class); 
    i.putExtra(NotesDbAdapter.KEY_ROWID, id); 
    startActivityForResult(i, ACTIVITY_EDIT); 
} 

@Override 
protected void onActivityResult(int requestCode, int resultCode, Intent intent) { 
    super.onActivityResult(requestCode, resultCode, intent); 
    fillData(); 
} 

}

Contact.class

public class Contact extends Activity implements OnClickListener{  
    private EditText mNameText; 
    private EditText mRankText; 
    private Long mRowId; 
    private NotesDbAdapter mDbHelper; 
    protected Cursor cursor; 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     mDbHelper = new NotesDbAdapter(this); 
     mDbHelper.open(); 
     setContentView(R.layout.contact); 

     Button adminButton = (Button) this.findViewById(R.id.admin); 
     adminButton.setOnClickListener(this); 

     mNameText = (EditText) findViewById(R.id.name); 
     mRankText = (EditText) findViewById(R.id.rank); 

     mRowId = (savedInstanceState == null) ? null : 
      (Long) savedInstanceState.getSerializable(NotesDbAdapter.KEY_ROWID); 
     if (mRowId == null) { 
      Bundle extras = getIntent().getExtras(); 
      mRowId = extras != null ? extras.getLong(NotesDbAdapter.KEY_ROWID) 
            : null;} 

      populateFields(); 
    }; 


private void populateFields() { 
    if (mRowId != null) { 
     Cursor note = mDbHelper.fetchsoldiers(mRowId); 
     startManagingCursor(note); 
     mNameText.setText(note.getString(
       note.getColumnIndexOrThrow(NotesDbAdapter.KEY_NAME))); 
     mRankText.setText(note.getString(
       note.getColumnIndexOrThrow(NotesDbAdapter.KEY_RANK))); 
    } 
} 

//@Override 
public void onClick(View v) { 
    String id = null; 
    switch (v.getId()) { 
    case R.id.admin: // doStuff 
     Intent intent = new Intent(this, Edit.class); 
     intent.putExtra(NotesDbAdapter.KEY_ROWID, id); 
     startActivity(intent); 
     Log.i("Onclick", "EndingTestNext");  
     break; 
}} 

} 

Edit.class

public class Edit extends Activity { 

private EditText mNameText; 
private EditText mRankText; 
private EditText mSsnText; 
private Long mRowId; 
private NotesDbAdapter mDbHelper; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    mDbHelper = new NotesDbAdapter(this); 
    mDbHelper.open(); 

    setContentView(R.layout.edit); 
    setTitle(R.string.edit_note); 

    mNameText = (EditText) findViewById(R.id.name); 
    mRankText = (EditText) findViewById(R.id.rank); 
    mSsnText = (EditText) findViewById(R.id.ssn); 

    Button confirmButton = (Button) findViewById(R.id.confirm); 


    mRowId = (savedInstanceState == null) ? null : 
     (Long) savedInstanceState.getSerializable(NotesDbAdapter.KEY_ROWID); 
    if (mRowId == null) { 
     Bundle extras = getIntent().getExtras(); 
     mRowId = extras != null ? extras.getLong(NotesDbAdapter.KEY_ROWID) 
           : null; 
    } 

    populateFields(); 

    confirmButton.setOnClickListener(new View.OnClickListener() { 

     public void onClick(View view) { 
      setResult(RESULT_OK); 
      finish(); 
     } 

    }); 
} 

private void populateFields() { 
    if (mRowId != null) { 
     Cursor note = mDbHelper.fetchNote(mRowId); 
     startManagingCursor(note); 
     mNameText.setText(note.getString(
       note.getColumnIndexOrThrow(NotesDbAdapter.KEY_NAME))); 
     mRankText.setText(note.getString(
       note.getColumnIndexOrThrow(NotesDbAdapter.KEY_RANK))); 
     mSsnText.setText(note.getString(
       note.getColumnIndexOrThrow(NotesDbAdapter.KEY_SSN))); 
    } 
} 

@Override 
protected void onSaveInstanceState(Bundle outState) { 
    super.onSaveInstanceState(outState); 
    saveState(); 
    outState.putSerializable(NotesDbAdapter.KEY_ROWID, mRowId); 
} 

@Override 
protected void onPause() { 
    super.onPause(); 
    saveState(); 
} 

@Override 
protected void onResume() { 
    super.onResume(); 
    populateFields(); 
} 

private void saveState() { 
    String name = mNameText.getText().toString(); 
    String rank = mRankText.getText().toString(); 
    String ssn = mSsnText.getText().toString(); 

    if (mRowId == null) { 
     long id = mDbHelper.createNote(name, rank, ssn); 
     if (id > 0) { 
      mRowId = id; 
     } 
    } else { 
     mDbHelper.updateNote(mRowId, name, rank, ssn); 
    } 
}} 

Answer 1

以下是我認爲正在發生的事情。 Contact類預計啓動它的Intent在KEY_ROWID鍵下應該有一個額外的Long。在您的onClick方法中，您正在設置字符串空值。當Contact.onCreate嘗試檢索它時，它將獲得一個顯式的空String值，該值不能分配給Long mRowId變量。只是不要調用putExtra，因爲你實際上沒有任何數據可以傳遞。

Answer 2

在第一個代碼中，onListItemClick（）中的id是一個數字行ID，它在數據庫中用作KEY_ROWID。這就是它作爲額外數據傳遞的原因。在切換到使用按鈕和OnClick（）時，按鈕代碼只具有（聯繫人）視圖，而不是您正在編輯的rowid。所以你想確保你以某種方式將行ID傳遞給Contact的意圖，這樣按鈕單擊OnClick（）可以將該rowid作爲id的值傳遞給Edit類。像你一樣，你不能將它設置爲null。它真的需要是你正在查看的數據庫的行ID，所以你的按鈕可以調用編輯類