日记基于Android开发代码

以下是一个简单的日记本Android App的代码示例，包括添加、编辑、删除和展示日记的功能：

1. MainActivity.java

public class MainActivity extends AppCompatActivity {
    private ListView diaryListView;
    private ArrayList<Diary> diaryArrayList;
    private DiaryAdapter diaryAdapter;
    private static final int ADD_DIARY_REQUEST_CODE = 1;
    private static final int EDIT_DIARY_REQUEST_CODE = 2;

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

        diaryListView = findViewById(R.id.diary_list_view);
        diaryArrayList = new ArrayList<>();
        diaryAdapter = new DiaryAdapter(MainActivity.this, diaryArrayList);
        diaryListView.setAdapter(diaryAdapter);
        diaryListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Diary diary = diaryArrayList.get(position);
                Intent intent = new Intent(MainActivity.this, EditDiaryActivity.class);
                intent.putExtra("diary", diary);
                intent.putExtra("position", position);
                startActivityForResult(intent, EDIT_DIARY_REQUEST_CODE);
            }
        });
        diaryListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
                diaryArrayList.remove(position);
                diaryAdapter.notifyDataSetChanged();
                return true;
            }
        });

        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, AddDiaryActivity.class);
                startActivityForResult(intent, ADD_DIARY_REQUEST_CODE);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK) {
            switch (requestCode) {
                case ADD_DIARY_REQUEST_CODE:
                    Diary diary = (Diary) data.getSerializableExtra("diary");
                    diaryArrayList.add(diary);
                    diaryAdapter.notifyDataSetChanged();
                    break;
                case EDIT_DIARY_REQUEST_CODE:
                    Diary diary1 = (Diary) data.getSerializableExtra("diary");
                    int position = data.getIntExtra("position", -1);
                    if (position != -1) {
                        diaryArrayList.set(position, diary1);
                        diaryAdapter.notifyDataSetChanged();
                    }
                    break;
            }
        }
    }
}

2. AddDiaryActivity.java

public class AddDiaryActivity extends AppCompatActivity {
    private EditText titleEditText;
    private EditText contentEditText;
    private Button addButton;

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

        titleEditText = findViewById(R.id.title_edit_text);
        contentEditText = findViewById(R.id.content_edit_text);
        addButton = findViewById(R.id.add_button);
        addButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String title = titleEditText.getText().toString();
                String content = contentEditText.getText().toString();
                Diary diary = new Diary(title, content);
                Intent intent = new Intent();
                intent.putExtra("diary", diary);
                setResult(RESULT_OK, intent);
                finish();
            }
        });
    }
}

3. EditDiaryActivity.java

public class EditDiaryActivity extends AppCompatActivity {
    private EditText titleEditText;
    private EditText contentEditText;
    private Button saveButton;
    private Diary diary;
    private int position;

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

        titleEditText = findViewById(R.id.title_edit_text);
        contentEditText = findViewById(R.id.content_edit_text);
        saveButton = findViewById(R.id.save_button);

        diary = (Diary) getIntent().getSerializableExtra("diary");
        position = getIntent().getIntExtra("position", -1);
        if (diary != null) {
            titleEditText.setText(diary.getTitle());
            contentEditText.setText(diary.getContent());
        }

        saveButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String title = titleEditText.getText().toString();
                String content = contentEditText.getText().toString();
                diary.setTitle(title);
                diary.setContent(content);
                Intent intent = new Intent();
                intent.putExtra("diary", diary);
                intent.putExtra("position", position);
                setResult(RESULT_OK, intent);
                finish();
            }
        });
    }
}

4. Diary.java

public class Diary implements Serializable {
    private String title;
    private String content;

    public Diary(String title, String content) {
        this.title = title;
        this.content = content;
    }

    public String getTitle() {
        return title;
    }

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

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }
}

5. DiaryAdapter.java

public class DiaryAdapter extends ArrayAdapter<Diary> {
    private Context context;
    private ArrayList<Diary> diaryArrayList;

    public DiaryAdapter(Context context, ArrayList<Diary> diaryArrayList) {
        super(context, 0, diaryArrayList);
        this.context = context;
        this.diaryArrayList = diaryArrayList;
    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
        if (convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.list_item_diary, parent, false);
        }

        TextView titleTextView = convertView.findViewById(R.id.title_text_view);
        TextView contentTextView = convertView.findViewById(R.id.content_text_view);

        Diary diary = diaryArrayList.get(position);

        titleTextView.setText(diary.getTitle());
        contentTextView.setText(diary.getContent());

        return convertView;
    }
}

这些代码示例提供了一个简单的日记本应用程序的实现，其中包括添加、编辑、删除和展示日记的功能。你可以根据自己的需求进行修改和补充。