java - 重新保存对象而不是在列表中创建新对象

Question

已解决 - 答案在线程末尾

我正在创建一个笔记应用程序。在该应用程序中，到目前为止一切进展顺利，除了当我尝试编辑注释(在回收器 View 中)并单击“保存”时，它会创建一个新注释，而不是重新保存现有注释的内容 。因为我没有办法再次保存它，因为我不知道如何去做。以下是我在 Activity CreateNoteActivity.java

中保存注释的方法

    // FAB
    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
        // Check to see if at least one field is populated with data
            String title = etTitle.getText().toString();
            String description = etDescription.getText().toString();
            title = title.trim(); // Remove whitespaces at the beginning/end
            description = description.trim();

            // Get intent extras
            Intent intent = getIntent();
            String alreadyCreatedTitle = intent.getStringExtra(CreateNoteActivity.EXTRA_TITLE);
            String alreadyCreatedDescription = intent.getStringExtra(CreateNoteActivity.EXTRA_DESCRIPTION);

            // Check to see if note title is empty, if it is, don't save
            if (title == "" || title.isEmpty()) {
                Snackbar snackbar = Snackbar.make(view, "Title may not be empty", Snackbar.LENGTH_SHORT);
                snackbar.show();
                // If the user clicked an already made note and did not change its contents, go back to MainActivity
            } else if (title.equals(alreadyCreatedTitle) && description.equals(alreadyCreatedDescription)) {
                finish();
                CreateNoteActivity.didClick = false;
                // The user is editing a note
            } else if (didClick) {
                // If the title or description is different then resave the note
                if (!title.equals(alreadyCreatedTitle) || !description.equals(alreadyCreatedDescription)) {
                    // TODO: Make it resave the note object

                }
            } else {
                saveNote();
                CreateNoteActivity.didClick = false;

            }
        }

    });
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}

之后，进入我的 MainActivity.java 类，其中 onActivityResult() 处理数据并保存新注释，或更新现有注释(尚未实现)

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == 123) {
        if (resultCode == Activity.RESULT_OK) {
            String passedTitle = data.getStringExtra(CreateNoteActivity.EXTRA_TITLE);
            String passedDescription = data.getStringExtra(CreateNoteActivity.EXTRA_DESCRIPTION);
            if (CreateNoteActivity.didClick) { // User is saving an existing note
                // TODO: Resave the existing note object
                // **************************
            } else { // User is creating a new note
                notes.add(new Note(passedTitle, passedDescription));
            }
        }
        refreshAdapter();
        if (resultCode == Activity.RESULT_CANCELED) {
            // Do something if it's cancelled. Happens when you click the back button for example
        }
    }
}

正如你所看到的，我在这个类中有一个静态 boolean 变量“CreateNoteActivity.didClick = false;”，我用它来跟踪用户是否单击了注释，并且它让他们参与了这项 Activity 。

我在我的适配器类中跟踪它

    @Override
    public void onClick(View view) {
        CreateNoteActivity.didClick = true;
        Log.d("TAG", "onClick() called on row: " + getAdapterPosition());
        Intent intent = new Intent(context, CreateNoteActivity.class);
        intent.putExtra(CreateNoteActivity.EXTRA_TITLE, titleTV.getText().toString());
        intent.putExtra(CreateNoteActivity.EXTRA_DESCRIPTION, descriptionTV.getText().toString());
        ((Activity) context).startActivityForResult(intent, 123);
    }

因此，当用户单击特定索引处的注释时，它会将 Intent 附加信息传递给 CreateNoteActivity.java，以便它可以检索它们，并使用其信息填充编辑文本。所以现在我想做的是，如果用户单击“保存”，它不会创建新注释，而是重新保存旧注释

我真的很感谢任何人为解决这个问题提供的帮助和反馈。已经坚持了几个小时了，我只是不知道如何解决这个问题。非常感谢。

我的简单笔记课

public class Note {

    private String title;
    private String description;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public Note(String title, String description) {
        this.title = title;
        this.description = description;
    }

    public Note() {
        // Empty
    }


}

解决方案

所以我最终做的是创建一个 static int 并将其设置为 getAdapterPosition() ，以便我始终可以获得某个对象所在的位置。然后我将它作为一个 Intent 额外传递并检索它，以便我可以处理它。在该指定索引处将其删除，并在该索引处设置一个新索引。

        if (CreateNoteActivity.didClick) { // User is saving an existing note
            note.setTitle(passedTitle);
            note.setDescription(passedDescription);
            notes.remove(passedID); // Remove note so I can put that same one at the top
            notes.add(0, note); // Put note at top of list
            CreateNoteActivity.didClick = false;
            recyclerView.scrollToPosition(0); // Scroll to top
        } else { // User is creating a new note
            note.setTitle(passedTitle);
            note.setDescription(passedDescription);
            notes.add(0, note);
            recyclerView.scrollToPosition(0);
        }
    } 

Answer 1

您还应该存储 Note 的 id 并传递它以便能够进行编辑。您可以使用其位置作为 id。

if (CreateNoteActivity.didClick) { // User is saving an existing note
     Note anote = notes.getItem(passedNoteId);
     anote.setTitle(passedTitle);
     anote.setDescription(passedDescription);
} else { // User is creating a new note
     notes.add(new Note(passedTitle, passedDescription));
}