代码

src/NoteApp281/app/src/main/java/com/example/noteapp281/AddActivity.java

@@ -0,0 +1,61 @@
+package com.example.noteapp281;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+import android.os.Bundle;
+import android.text.TextUtils;
+import android.view.View;
+import android.widget.EditText;
+
+import com.example.noteapp281.bean.Note;
+import com.example.noteapp281.util.ToastUtil;
+
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+public class AddActivity extends AppCompatActivity {
+
+    private EditText etTitle,etContent;
+
+    private NoteDbOpenHelper mNoteDbOpenHelper;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_add);
+
+        etTitle = findViewById(R.id.et_title);
+        etContent = findViewById(R.id.et_content);
+        mNoteDbOpenHelper = new NoteDbOpenHelper(this);
+
+    }
+
+    public void add(View view) {
+        String title = etTitle.getText().toString();
+        String content = etContent.getText().toString();
+        if (TextUtils.isEmpty(title)) {
+            ToastUtil.toastShort(this, "标题不能为空！");
+            return;
+        }
+
+        Note note = new Note();
+
+        note.setTitle(title);
+        note.setContent(content);
+        note.setCreatedTime(getCurrentTimeFormat());
+        long row = mNoteDbOpenHelper.insertData(note);
+        if (row != -1) {
+            ToastUtil.toastShort(this,"添加成功！");
+            this.finish();
+        }else {
+            ToastUtil.toastShort(this,"添加失败！");
+        }
+
+    }
+
+    private String getCurrentTimeFormat() {
+        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("YYYY年MM月dd HH:mm:ss");
+        Date date = new Date();
+        return simpleDateFormat.format(date);
+    }
+}

src/NoteApp281/app/src/main/java/com/example/noteapp281/EditActivity.java

@@ -0,0 +1,71 @@
+package com.example.noteapp281;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.text.TextUtils;
+import android.view.View;
+import android.widget.EditText;
+
+import com.example.noteapp281.bean.Note;
+import com.example.noteapp281.util.ToastUtil;
+
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+public class EditActivity extends AppCompatActivity {
+
+    private Note note;
+    private EditText etTitle,etContent;
+
+    private NoteDbOpenHelper mNoteDbOpenHelper;
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_edit);
+
+        etTitle = findViewById(R.id.et_title);
+        etContent = findViewById(R.id.et_content);
+
+        initData();
+
+    }
+
+    private void initData() {
+        Intent intent = getIntent();
+        note = (Note) intent.getSerializableExtra("note");
+        if (note != null) {
+            etTitle.setText(note.getTitle());
+            etContent.setText(note.getContent());
+        }
+        mNoteDbOpenHelper = new NoteDbOpenHelper(this);
+    }
+
+    public void save(View view) {
+        String title = etTitle.getText().toString();
+        String content = etContent.getText().toString();
+        if (TextUtils.isEmpty(title)) {
+            ToastUtil.toastShort(this, "标题不能为空！");
+            return;
+        }
+
+        note.setTitle(title);
+        note.setContent(content);
+        note.setCreatedTime(getCurrentTimeFormat());
+        long rowId = mNoteDbOpenHelper.updateData(note);
+        if (rowId != -1) {
+            ToastUtil.toastShort(this, "修改成功！");
+            this.finish();
+        }else{
+            ToastUtil.toastShort(this, "修改失败！");
+        }
+
+    }
+
+    private String getCurrentTimeFormat() {
+        SimpleDateFormat sdf = new SimpleDateFormat("YYYY年MM月dd日 HH:mm:ss");
+        Date date = new Date();
+        return sdf.format(date);
+    }
+}

src/NoteApp281/app/src/main/java/com/example/noteapp281/MainActivity.java

@@ -0,0 +1,191 @@
+package com.example.noteapp281;
+
+import android.app.SearchManager;
+import android.content.Context;
+import android.content.Intent;
+import android.os.Bundle;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.view.View;
+
+import androidx.annotation.NonNull;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.appcompat.widget.SearchView;
+import androidx.recyclerview.widget.GridLayoutManager;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+
+import com.example.noteapp281.adapter.MyAdapter;
+import com.example.noteapp281.bean.Note;
+import com.example.noteapp281.util.SpfUtil;
+import com.google.android.material.floatingactionbutton.FloatingActionButton;
+
+import java.text.SimpleDateFormat;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+
+public class MainActivity extends AppCompatActivity {
+
+    private RecyclerView mRecyclerView;
+    private FloatingActionButton mBtnAdd;
+    private List<Note> mNotes;
+    private MyAdapter mMyAdapter;
+
+    private NoteDbOpenHelper mNoteDbOpenHelper;
+
+    public static final int MODE_LINEAR = 0;
+    public static final int MODE_GRID = 1;
+
+    public static final String KEY_LAYOUT_MODE = "key_layout_mode";
+
+    private int currentListLayoutMode = MODE_LINEAR;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+        initView();
+        initData();
+        initEvent();
+    }
+
+    @Override
+    protected void onResume() {
+        super.onResume();
+        refreshDataFromDb();
+        setListLayout();
+    }
+
+    private void setListLayout() {
+        currentListLayoutMode = SpfUtil.getIntWithDefault(this, KEY_LAYOUT_MODE, MODE_LINEAR);
+        if (currentListLayoutMode == MODE_LINEAR) {
+            setToLinearList();
+        }else{
+            setToGridList();
+        }
+    }
+
+    private void refreshDataFromDb() {
+        mNotes = getDataFromDB();
+        mMyAdapter.refreshData(mNotes);
+    }
+
+    private void initEvent() {
+        mMyAdapter = new MyAdapter(this, mNotes);
+        mRecyclerView.setAdapter(mMyAdapter);
+//        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
+//        mRecyclerView.setLayoutManager(linearLayoutManager);
+//        mMyAdapter.setViewType(MyAdapter.TYPE_LINEAR_LAYOUT);
+        setListLayout();
+
+    }
+
+    private void initData() {
+        mNotes = new ArrayList<>();
+        mNoteDbOpenHelper = new NoteDbOpenHelper(this);
+//
+//        for (int i = 0; i < 30; i++) {
+//            Note note = new Note();
+//            note.setTitle("这是标题"+i);
+//            note.setContent("这是内容"+i);
+//            note.setCreatedTime(getCurrentTimeFormat());
+//            mNotes.add(note);
+//        }
+
+//        mNotes = getDataFromDB();
+
+    }
+
+    private List<Note> getDataFromDB() {
+       return mNoteDbOpenHelper.queryAllFromDb();
+    }
+
+    private String getCurrentTimeFormat() {
+        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy年MM月dd HH:mm:ss");
+        Date date = new Date();
+        return simpleDateFormat.format(date);
+    }
+
+    private void initView() {
+        mRecyclerView = findViewById(R.id.rlv);
+    }
+
+
+    public void add(View view) {
+        Intent intent = new Intent(this, AddActivity.class);
+        startActivity(intent);
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        getMenuInflater().inflate(R.menu.menu_main, menu);
+        SearchView searchView = (SearchView) menu.findItem(R.id.menu_search).getActionView();
+
+        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
+            @Override
+            public boolean onQueryTextSubmit(String query) {
+                return false;
+            }
+
+            @Override
+            public boolean onQueryTextChange(String newText) {
+                mNotes = mNoteDbOpenHelper.queryFromDbByTitle(newText);
+                mMyAdapter.refreshData(mNotes);
+                return true;
+            }
+        });
+        return super.onCreateOptionsMenu(menu);
+    }
+
+
+    @Override
+    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
+        item.setChecked(true);
+
+        switch (item.getItemId()) {
+
+            case R.id.menu_linear:
+                setToLinearList();
+                currentListLayoutMode = MODE_LINEAR;
+                SpfUtil.saveInt(this,KEY_LAYOUT_MODE,MODE_LINEAR);
+
+                return true;
+            case R.id.menu_grid:
+
+                setToGridList();
+                currentListLayoutMode = MODE_GRID;
+                SpfUtil.saveInt(this,KEY_LAYOUT_MODE,MODE_GRID);
+                return true;
+            default:
+                return super.onOptionsItemSelected(item);
+
+        }
+    }
+
+    private void setToLinearList() {
+        RecyclerView.LayoutManager linearLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
+        mRecyclerView.setLayoutManager(linearLayoutManager);
+        mMyAdapter.setViewType(MyAdapter.TYPE_LINEAR_LAYOUT);
+        mMyAdapter.notifyDataSetChanged();
+    }
+
+
+    private void setToGridList() {
+        RecyclerView.LayoutManager gridLayoutManager = new GridLayoutManager(this, 2);
+        mRecyclerView.setLayoutManager(gridLayoutManager);
+        mMyAdapter.setViewType(MyAdapter.TYPE_GRID_LAYOUT);
+        mMyAdapter.notifyDataSetChanged();
+    }
+
+    @Override
+    public boolean onPrepareOptionsMenu(Menu menu) {
+        if (currentListLayoutMode == MODE_LINEAR) {
+            MenuItem item = menu.findItem(R.id.menu_linear);
+            item.setChecked(true);
+        } else {
+            menu.findItem(R.id.menu_grid).setChecked(true);
+        }
+        return super.onPrepareOptionsMenu(menu);
+    }
+}

src/NoteApp281/app/src/main/java/com/example/noteapp281/NoteDbOpenHelper.java

@@ -0,0 +1,130 @@
+package com.example.noteapp281;
+
+import android.content.ContentValues;
+import android.content.Context;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.text.TextUtils;
+
+import com.example.noteapp281.bean.Note;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class NoteDbOpenHelper extends SQLiteOpenHelper {
+
+    private static final String DB_NAME = "noteSQLite.db";
+    private static final String TABLE_NAME_NOTE = "note";
+
+    private static final String CREATE_TABLE_SQL = "create table " + TABLE_NAME_NOTE + " (id integer primary key autoincrement, title text, content text, create_time text)";
+
+
+    public NoteDbOpenHelper(Context context) {
+        super(context, DB_NAME, null, 1);
+    }
+
+
+
+    @Override
+    public void onCreate(SQLiteDatabase db) {
+        db.execSQL(CREATE_TABLE_SQL);
+
+    }
+
+    @Override
+    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+
+    }
+
+    public long insertData(Note note) {
+
+        SQLiteDatabase db = getWritableDatabase();
+
+        ContentValues values = new ContentValues();
+        values.put("title", note.getTitle());
+        values.put("content", note.getContent());
+        values.put("create_time", note.getCreatedTime());
+
+        return db.insert(TABLE_NAME_NOTE, null, values);
+    }
+
+    public int deleteFromDbById(String id) {
+        SQLiteDatabase db = getWritableDatabase();
+//        return db.delete(TABLE_NAME_NOTE, "id = ?", new String[]{id});
+//        return db.delete(TABLE_NAME_NOTE, "id is ?", new String[]{id});
+        return db.delete(TABLE_NAME_NOTE, "id like ?", new String[]{id});
+    }
+
+    public int updateData(Note note) {
+
+        SQLiteDatabase db = getWritableDatabase();
+
+        ContentValues values = new ContentValues();
+        values.put("title", note.getTitle());
+        values.put("content", note.getContent());
+        values.put("create_time", note.getCreatedTime());
+
+        return db.update(TABLE_NAME_NOTE, values, "id like ?", new String[]{note.getId()});
+    }
+
+    public List<Note> queryAllFromDb() {
+
+        SQLiteDatabase db = getWritableDatabase();
+        List<Note> noteList = new ArrayList<>();
+
+        Cursor cursor = db.query(TABLE_NAME_NOTE, null, null, null, null, null, null);
+        if (cursor != null) {
+            while (cursor.moveToNext()) {
+                String id = cursor.getString(cursor.getColumnIndex("id"));
+                String title = cursor.getString(cursor.getColumnIndex("title"));
+                String content = cursor.getString(cursor.getColumnIndex("content"));
+                String createTime = cursor.getString(cursor.getColumnIndex("create_time"));
+
+                Note note = new Note();
+                note.setId(id);
+                note.setTitle(title);
+                note.setContent(content);
+                note.setCreatedTime(createTime);
+
+                noteList.add(note);
+            }
+            cursor.close();
+        }
+
+        return noteList;
+
+    }
+
+    public List<Note> queryFromDbByTitle(String title) {
+        if (TextUtils.isEmpty(title)) {
+            return queryAllFromDb();
+        }
+
+        SQLiteDatabase db = getWritableDatabase();
+        List<Note> noteList = new ArrayList<>();
+
+        Cursor cursor = db.query(TABLE_NAME_NOTE, null, "title like ?", new String[]{"%"+title+"%"}, null, null, null);
+
+        if (cursor != null) {
+
+            while (cursor.moveToNext()) {
+                String id = cursor.getString(cursor.getColumnIndex("id"));
+                String title2 = cursor.getString(cursor.getColumnIndex("title"));
+                String content = cursor.getString(cursor.getColumnIndex("content"));
+                String createTime = cursor.getString(cursor.getColumnIndex("create_time"));
+
+                Note note = new Note();
+                note.setId(id);
+                note.setTitle(title2);
+                note.setContent(content);
+                note.setCreatedTime(createTime);
+                noteList.add(note);
+            }
+            cursor.close();
+        }
+        return noteList;
+    }
+
+
+}

src/NoteApp281/app/src/main/java/com/example/noteapp281/adapter/MyAdapter.java

@@ -0,0 +1,230 @@
+package com.example.noteapp281.adapter;
+
+import android.app.Dialog;
+import android.content.Context;
+import android.content.Intent;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
+
+import com.example.noteapp281.EditActivity;
+import com.example.noteapp281.NoteDbOpenHelper;
+import com.example.noteapp281.R;
+import com.example.noteapp281.bean.Note;
+import com.example.noteapp281.util.ToastUtil;
+
+import java.util.List;
+
+public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
+
+    private List<Note> mBeanList;
+    private LayoutInflater mLayoutInflater;
+    private Context mContext;
+
+    private NoteDbOpenHelper mNoteDbOpenHelper;
+
+    private int viewType;
+
+    public static int TYPE_LINEAR_LAYOUT = 0;
+    public static int TYPE_GRID_LAYOUT = 1;
+
+    public MyAdapter(Context context, List<Note> mBeanList){
+        this.mBeanList = mBeanList;
+        this.mContext = context;
+        mLayoutInflater = LayoutInflater.from(mContext);
+        mNoteDbOpenHelper = new NoteDbOpenHelper(mContext);
+    }
+
+    public void setViewType(int viewType) {
+        this.viewType = viewType;
+    }
+
+    @Override
+    public int getItemViewType(int position) {
+        return viewType;
+    }
+
+    @NonNull
+    @Override
+    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        if(viewType == TYPE_LINEAR_LAYOUT){
+            View view = mLayoutInflater.inflate(R.layout.list_item_layout, parent, false);
+            MyViewHolder myViewHolder = new MyViewHolder(view);
+            return myViewHolder;
+        }else if(viewType == TYPE_GRID_LAYOUT){
+            View view = mLayoutInflater.inflate(R.layout.list_item_grid_layout, parent, false);
+            MyGridViewHolder myGridViewHolder = new MyGridViewHolder(view);
+            return myGridViewHolder;
+        }
+
+        return null;
+    }
+
+    @Override
+    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
+        if (holder == null) {
+            return;
+        }
+        if(holder instanceof MyViewHolder){
+            bindMyViewHolder((MyViewHolder) holder, position);
+        } else if (holder instanceof MyGridViewHolder) {
+            bindGridViewHolder((MyGridViewHolder) holder, position);
+        }
+    }
+
+    private void bindMyViewHolder(MyViewHolder holder, int position) {
+        Note note = mBeanList.get(position);
+        holder.mTvTitle.setText(note.getTitle());
+        holder.mTvContent.setText(note.getContent());
+        holder.mTvTime.setText(note.getCreatedTime());
+        holder.rlContainer.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+
+                Intent intent = new Intent(mContext, EditActivity.class);
+                intent.putExtra("note", note);
+                mContext.startActivity(intent);
+            }
+        });
+
+        holder.rlContainer.setOnLongClickListener(new View.OnLongClickListener() {
+            @Override
+            public boolean onLongClick(View v) {
+                // 弹出弹窗
+                Dialog dialog = new Dialog(mContext, android.R.style.ThemeOverlay_Material_Dialog_Alert);
+                View dialogView = mLayoutInflater.inflate(R.layout.list_item_dialog_layout, null);
+                TextView tvDelete = dialogView.findViewById(R.id.tv_delete);
+                TextView tvEdit = dialogView.findViewById(R.id.tv_edit);
+
+                tvDelete.setOnClickListener(new View.OnClickListener() {
+                    @Override
+                    public void onClick(View v) {
+                        int row = mNoteDbOpenHelper.deleteFromDbById(note.getId());
+                        if (row > 0) {
+                            removeData(position);
+                        }
+                        dialog.dismiss();
+                    }
+                });
+
+
+                tvEdit.setOnClickListener(new View.OnClickListener() {
+                    @Override
+                    public void onClick(View v) {
+                        Intent intent = new Intent(mContext, EditActivity.class);
+                        intent.putExtra("note", note);
+                        mContext.startActivity(intent);
+                        dialog.dismiss();
+                    }
+                });
+                dialog.setContentView(dialogView);
+                dialog.setCanceledOnTouchOutside(true);
+                dialog.show();
+                return true;
+            }
+        });
+    }
+
+
+    private void bindGridViewHolder(MyGridViewHolder holder, int position) {
+        Note note = mBeanList.get(position);
+        holder.mTvTitle.setText(note.getTitle());
+        holder.mTvContent.setText(note.getContent());
+        holder.mTvTime.setText(note.getCreatedTime());
+        holder.rlContainer.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+
+                Intent intent = new Intent(mContext, EditActivity.class);
+                intent.putExtra("note", note);
+                mContext.startActivity(intent);
+            }
+        });
+
+        holder.rlContainer.setOnLongClickListener(new View.OnLongClickListener() {
+            @Override
+            public boolean onLongClick(View v) {
+                // 弹出弹窗
+                Dialog dialog = new Dialog(mContext, android.R.style.ThemeOverlay_Material_Dialog_Alert);
+                View dialogView = mLayoutInflater.inflate(R.layout.list_item_dialog_layout, null);
+                TextView tvDelete = dialogView.findViewById(R.id.tv_delete);
+                TextView tvEdit = dialogView.findViewById(R.id.tv_edit);
+
+                tvDelete.setOnClickListener(new View.OnClickListener() {
+                    @Override
+                    public void onClick(View v) {
+                        int row = mNoteDbOpenHelper.deleteFromDbById(note.getId());
+                        if (row > 0) {
+                            removeData(position);
+                        }
+                        dialog.dismiss();
+                    }
+                });
+
+
+                tvEdit.setOnClickListener(new View.OnClickListener() {
+                    @Override
+                    public void onClick(View v) {
+                        Intent intent = new Intent(mContext, EditActivity.class);
+                        intent.putExtra("note", note);
+                        mContext.startActivity(intent);
+                        dialog.dismiss();
+                    }
+                });
+                dialog.setContentView(dialogView);
+                dialog.setCanceledOnTouchOutside(true);
+                dialog.show();
+                return true;
+            }
+        });
+    }
+
+    @Override
+    public int getItemCount() {
+        return mBeanList.size();
+    }
+
+    public void refreshData(List<Note> notes) {
+        this.mBeanList = notes;
+        notifyDataSetChanged();
+    }
+
+    public void removeData(int pos) {
+        mBeanList.remove(pos);
+        notifyItemRemoved(pos);
+    }
+
+    class MyViewHolder extends RecyclerView.ViewHolder{
+        TextView mTvTitle;
+        TextView mTvContent;
+        TextView mTvTime;
+        ViewGroup rlContainer;
+        public MyViewHolder(@NonNull View itemView) {
+            super(itemView);
+            this.mTvTitle = itemView.findViewById(R.id.tv_title);
+            this.mTvContent = itemView.findViewById(R.id.tv_content);
+            this.mTvTime = itemView.findViewById(R.id.tv_time);
+            this.rlContainer = itemView.findViewById(R.id.rl_item_container);
+        }
+    }
+
+    class MyGridViewHolder extends RecyclerView.ViewHolder{
+
+        TextView mTvTitle;
+        TextView mTvContent;
+        TextView mTvTime;
+        ViewGroup rlContainer;
+
+        public MyGridViewHolder(@NonNull View itemView) {
+            super(itemView);
+            this.mTvTitle = itemView.findViewById(R.id.tv_title);
+            this.mTvContent = itemView.findViewById(R.id.tv_content);
+            this.mTvTime = itemView.findViewById(R.id.tv_time);
+            this.rlContainer = itemView.findViewById(R.id.rl_item_container);
+        }
+    }
+}

src/NoteApp281/app/src/main/java/com/example/noteapp281/bean/Note.java

@@ -0,0 +1,54 @@
+package com.example.noteapp281.bean;
+
+import java.io.Serializable;
+
+public class Note implements Serializable {
+
+    private String title;
+    private String content;
+    private String createdTime;
+    private String id;
+
+
+    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;
+    }
+
+    public String getCreatedTime() {
+        return createdTime;
+    }
+
+    public void setCreatedTime(String createdTime) {
+        this.createdTime = createdTime;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    @Override
+    public String toString() {
+        return "Note{" +
+                "title='" + title + '\'' +
+                ", content='" + content + '\'' +
+                ", createdTime='" + createdTime + '\'' +
+                ", id='" + id + '\'' +
+                '}';
+    }
+}

src/NoteApp281/app/src/main/java/com/example/noteapp281/util/SpfUtil.java

@@ -0,0 +1,38 @@
+package com.example.noteapp281.util;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+
+public class SpfUtil {
+
+    private static String SPF_NAME = "noteSpf";
+
+    public static void saveString(Context context, String key, String value) {
+        SharedPreferences spf = context.getSharedPreferences(SPF_NAME, Context.MODE_PRIVATE);
+        SharedPreferences.Editor edit = spf.edit();
+        edit.putString(key, value);
+        edit.apply();
+    }
+
+    public static String getString(Context context, String key) {
+        SharedPreferences spf = context.getSharedPreferences(SPF_NAME, Context.MODE_PRIVATE);
+        return spf.getString(key, "");
+    }
+
+    public static void saveInt(Context context, String key, int value) {
+        SharedPreferences spf = context.getSharedPreferences(SPF_NAME, Context.MODE_PRIVATE);
+        SharedPreferences.Editor edit = spf.edit();
+        edit.putInt(key, value);
+        edit.apply();
+    }
+
+    public static int getInt(Context context, String key) {
+        SharedPreferences spf = context.getSharedPreferences(SPF_NAME, Context.MODE_PRIVATE);
+        return spf.getInt(key, -1);
+    }
+
+    public static int getIntWithDefault(Context context, String key, int defValue) {
+        SharedPreferences spf = context.getSharedPreferences(SPF_NAME, Context.MODE_PRIVATE);
+        return spf.getInt(key, defValue);
+    }
+}

src/NoteApp281/app/src/main/java/com/example/noteapp281/util/ToastUtil.java

@@ -0,0 +1,15 @@
+package com.example.noteapp281.util;
+
+import android.content.Context;
+import android.widget.Toast;
+
+public class ToastUtil {
+
+    public static void toastShort(Context context, String msg) {
+        Toast.makeText(context, msg, Toast.LENGTH_SHORT).show();
+    }
+
+    public static void toastLong(Context context, String msg) {
+        Toast.makeText(context, msg, Toast.LENGTH_LONG).show();
+    }
+}