Question

我目前的java代码存在问题。每次点击我的视图按钮，我的应用程序都会崩溃。在我的logcat上，我收到一条错误消息

引起：java.lang.NullPointerException，另一个错误是 java.lang.RuntimeException：无法启动活动 ComponentInfo {com.example.moviemanager / com.example.moviemanager.viewmoviedetails}：显示java.lang.NullPointerException **

这是我的viewmoviedetails代码：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.viewmoviedetail);

    keyEditText = (EditText)findViewById(R.id.keyeditText);
    titleEditText = (EditText)findViewById(R.id.titleeditText);
    typeEditText = (EditText)findViewById(R.id.typeeditText);
    storyEditText = (EditText)findViewById(R.id.storyeditText);
    ratingEditText = (EditText)findViewById(R.id.ratingeditText);
    languageEditText = (EditText)findViewById(R.id.languageeditText);
    runtimeEditText = (EditText)findViewById(R.id.runtimeeditText);

    Bundle extras = getIntent().getExtras();
    rowID = extras.getLong("row_id");

    Button btnback = (Button)findViewById(R.id.backbutton);
    btnback.setOnClickListener(backButtonClicked);
}
OnClickListener backButtonClicked = new OnClickListener(){
    @Override
    public void onClick(View v){
        finish();
    }
};
@Override
protected void onResume(){
    super.onResume();
    new LoadMovieTask().execute(rowID);
}

private class LoadMovieTask extends AsyncTask<Long, Object, Cursor>{
    DatabaseHandler dh = new DatabaseHandler(viewmoviedetails.this);

    @Override
    protected Cursor doInBackground(Long... params){
        dh.open();
        return dh.getRow(params[0]);
    }

    @Override
    protected void onPostExecute(Cursor result){
        super.onPostExecute(result);
        result.moveToFirst();
        int keyindex = result.getColumnIndex("mvkey");
        int titleindex = result.getColumnIndex("mvtitle");
        int typeindex = result.getColumnIndex("mvtype");
        int storyindex = result.getColumnIndex("mvstory");
        int ratingindex = result.getColumnIndex("mvrating");
        int languageindex = result.getColumnIndex("mvlanguage");
        int runtimeindex = result.getColumnIndex("mvruntime");

        keyEditText.setText(result.getString(keyindex));
        titleEditText.setText(result.getString(titleindex));
        typeEditText.setText(result.getString(typeindex));
        storyEditText.setText(result.getString(storyindex));
        ratingEditText.setText(result.getString(ratingindex));
        languageEditText.setText(result.getString(languageindex));
        runtimeEditText.setText(result.getString(runtimeindex));

        result.close();
        dh.close();
    }
}

有人可以帮助我解决我的错误。提前致谢

Answer 1

extras null方法中的Activity似乎为onCreate()。

修改

在ViewMovie课程中，您将使用
开始下一个Activity
i = new Intent(this, com.example.moviemanager.viewmoviedetails.class); startActivity(i);

问题是您没有将额外数据添加到Intent，所以当您致电时

Bundle extras = getIntent().getExtras();
在ViewMovieDetails中
，您获得null。

您需要将额外内容添加到Intent，如下所示：

i = new Intent(this, com.example.moviemanager.viewmoviedetails.class); i.putExtra("row_id", (long) row_id) startActivity(i);

其中row_id是您要传递的long值。然后将ViewMovieDetails中的值恢复为

rowID = getIntent().getLongExtra("row_id", 0L);

这样可行。

无法在eclipse上启动活动componentInfo

1 个答案: