这篇文章将为大家详细讲解有关android如何实现记事本app，小编觉得挺实用的，因此分享给大家做个参考，希望大家阅读完这篇文章后可以有所收获。
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自己写的一个简单的记事本app，效果如下：
一、首先是第一个界面的编写，最上面是一个TextView，中间是一个Linearlayout中嵌套一个listview布局，最下面是一个button。下面附上第一个页面的简单布局xml文件。
至于button的样式btn_selector就是自己定义的button样式。
二、其次就是设置ListView中数据显示的xml文件，代码如下：
三、编写第二个界面样式，第二个界面是最上面一个linearlayout，里面包含两个button和一个TextView。代码如下：
四、将日志的数据保存在数据库中，使用sqlite来创建数据库，数据库中有三个属性，"_id"、"content"、"date"这三个属性，创建一个NoteDB来创建数据库。
package com.example.datenote;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class NotesDB extends SQLiteOpenHelper {
public static final String TABLE_NAME_NOTES = "note";
public static final String COLUMN_NAME_ID = "_id";
public static final String COLUMN_NAME_NOTE_CONTENT = "content";
public static final String COLUMN_NAME_NOTE_DATE = "date";
public NotesDB(Context context) {
super(context, "note", null, 1);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql = "CREATE TABLE " + TABLE_NAME_NOTES + "(" + COLUMN_NAME_ID
+ " INTEGER PRIMARY KEY AUTOINCREMENT,"
+ COLUMN_NAME_NOTE_CONTENT + " TEXT NOT NULL DEFAULT\"\","
+ COLUMN_NAME_NOTE_DATE + " TEXT NOT NULL DEFAULT\"\"" + ")";
Log.d("SQL", sql);
db.execSQL(sql);
// String sql1="insert into "+TABLE_NAME_NOTES+"values("+"1,"+"'写作业',"+"'晚上要写作业的干活'"+")";
// Log.d("SQL1", sql1);
// db.execSQL(sql1);
// ContentValues values=new ContentValues();
// values.put("id",1);
// values.put("content","写作业");
// values.put("date", "2013-1-2");
// db.insert("note", null, values);
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
// TODO Auto-generated method stub
}
}五、实现点击添加事件的跳转,在第一个页面中点击添加备忘录后会跳转到第二个界面，设置点击事件，由一个activity跳转到另外一个activity，我使用的是intent方式。另外，在ListView中点击每个已记录下来的日志也会跳转到第二个界面，只是显示的不是空白的EditText，而是包含日志的EditText。MainActivity如下：
package com.example.datenote;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity implements OnScrollListener,
OnItemClickListener, OnItemLongClickListener {
private Context mContext;
private ListView listview;
private SimpleAdapter simp_adapter;
private List> dataList;
private Button addNote;
private TextView tv_content;
private NotesDB DB;
private SQLiteDatabase dbread;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main);
tv_content = (TextView) findViewById(R.id.tv_content);
listview = (ListView) findViewById(R.id.listview);
dataList = new ArrayList>();
addNote = (Button) findViewById(R.id.btn_editnote);
mContext = this;
addNote.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
noteEdit.ENTER_STATE = 0;
Intent intent = new Intent(mContext, noteEdit.class);
Bundle bundle = new Bundle();
bundle.putString("info", "");
intent.putExtras(bundle);
startActivityForResult(intent, 1);
}
});
DB = new NotesDB(this);
dbread = DB.getReadableDatabase();
// 清空数据库中表的内容
//dbread.execSQL("delete from note");
RefreshNotesList();
listview.setOnItemClickListener(this);
listview.setOnItemLongClickListener(this);
listview.setOnScrollListener(this);
}
public void RefreshNotesList() {
int size = dataList.size();
if (size > 0) {
dataList.removeAll(dataList);
simp_adapter.notifyDataSetChanged();
listview.setAdapter(simp_adapter);
}
simp_adapter = new SimpleAdapter(this, getData(), R.layout.item,
new String[] { "tv_content", "tv_date" }, new int[] {
R.id.tv_content, R.id.tv_date });
listview.setAdapter(simp_adapter);
}
private List> getData() {
Cursor cursor = dbread.query("note", null, "content!=\"\"", null, null,
null, null);
while (cursor.moveToNext()) {
String name = cursor.getString(cursor.getColumnIndex("content"));
String date = cursor.getString(cursor.getColumnIndex("date"));
Map map = new HashMap();
map.put("tv_content", name);
map.put("tv_date", date);
dataList.add(map);
}
cursor.close();
return dataList;
}
@Override
public void onScroll(AbsListView arg0, int arg1, int arg2, int arg3) {
// TODO Auto-generated method stub
}
// 滑动listview监听事件
@Override
public void onScrollStateChanged(AbsListView arg0, int arg1) {
// TODO Auto-generated method stub
switch (arg1) {
case SCROLL_STATE_FLING:
Log.i("main", "用户在手指离开屏幕之前，由于用力的滑了一下，视图能依靠惯性继续滑动");
case SCROLL_STATE_IDLE:
Log.i("main", "视图已经停止滑动");
case SCROLL_STATE_TOUCH_SCROLL:
Log.i("main", "手指没有离开屏幕，试图正在滑动");
}
}
// 点击listview中某一项的监听事件
@Override
public void onItemClick(AdapterView arg0, View arg1, int arg2, long arg3) {
noteEdit.ENTER_STATE = 1;
// Log.d("arg2", arg2 + "");
// TextView
// content=(TextView)listview.getChildAt(arg2).findViewById(R.id.tv_content);
// String content1=content.toString();
String content = listview.getItemAtPosition(arg2) + "";
String content1 = content.substring(content.indexOf("=") + 1,
content.indexOf(","));
Log.d("CONTENT", content1);
Cursor c = dbread.query("note", null,
"content=" + "'" + content1 + "'", null, null, null, null);
while (c.moveToNext()) {
String No = c.getString(c.getColumnIndex("_id"));
Log.d("TEXT", No);
// Intent intent = new Intent(mContext, noteEdit.class);
// intent.putExtra("data", text);
// setResult(4, intent);
// // intent.putExtra("data",text);
// startActivityForResult(intent, 3);
Intent myIntent = new Intent();
Bundle bundle = new Bundle();
bundle.putString("info", content1);
noteEdit.id = Integer.parseInt(No);
myIntent.putExtras(bundle);
myIntent.setClass(MainActivity.this, noteEdit.class);
startActivityForResult(myIntent, 1);
}
}
@Override
// 接受上一个页面返回的数据，并刷新页面
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// TODO Auto-generated method stub
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 1 && resultCode == 2) {
RefreshNotesList();
}
}
// 点击listview中某一项长时间的点击事件
@Override
public boolean onItemLongClick(AdapterView arg0, View arg1, int arg2,
long arg3) {
final int n=arg2;
Builder builder = new AlertDialog.Builder(this);
builder.setTitle("删除该日志");
builder.setMessage("确认删除吗？");
builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
String content = listview.getItemAtPosition(n) + "";
String content1 = content.substring(content.indexOf("=") + 1,
content.indexOf(","));
Cursor c = dbread.query("note", null, "content=" + "'"
+ content1 + "'", null, null, null, null);
while (c.moveToNext()) {
String id = c.getString(c.getColumnIndex("_id"));
String sql_del = "update note set content='' where _id="
+ id;
dbread.execSQL(sql_del);
RefreshNotesList();
}
}
});
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
builder.create();
builder.show();
return true;
}
}六、编写第二个跳转后界面的Activity，如下：
package com.example.datenote;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteStatement;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.view.WindowManager;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class noteEdit extends Activity {
private TextView tv_date;
private EditText et_content;
private Button btn_ok;
private Button btn_cancel;
private NotesDB DB;
private SQLiteDatabase dbread;
public static int ENTER_STATE = 0;
public static String last_content;
public static int id;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
// 设置无标题
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.edit);
tv_date = (TextView) findViewById(R.id.tv_date);
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");
String dateString = sdf.format(date);
tv_date.setText(dateString);
et_content = (EditText) findViewById(R.id.et_content);
// 设置软键盘自动弹出
getWindow().setSoftInputMode(
WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
DB = new NotesDB(this);
dbread = DB.getReadableDatabase();
Bundle myBundle = this.getIntent().getExtras();
last_content = myBundle.getString("info");
Log.d("LAST_CONTENT", last_content);
et_content.setText(last_content);
// 确认按钮的点击事件
btn_ok = (Button) findViewById(R.id.btn_ok);
btn_ok.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
// 获取日志内容
String content = et_content.getText().toString();
Log.d("LOG1", content);
// 获取写日志时间
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
String dateNum = sdf.format(date);
String sql;
String sql_count = "SELECT COUNT(*) FROM note";
SQLiteStatement statement = dbread.compileStatement(sql_count);
long count = statement.simpleQueryForLong();
Log.d("COUNT", count + "");
Log.d("ENTER_STATE", ENTER_STATE + "");
// 添加一个新的日志
if (ENTER_STATE == 0) {
if (!content.equals("")) {
sql = "insert into " + NotesDB.TABLE_NAME_NOTES
+ " values(" + count + "," + "'" + content
+ "'" + "," + "'" + dateNum + "')";
Log.d("LOG", sql);
dbread.execSQL(sql);
}
}
// 查看并修改一个已有的日志
else {
Log.d("执行命令", "执行了该函数");
String updatesql = "update note set content='"
+ content + "' where _id=" + id;
dbread.execSQL(updatesql);
// et_content.setText(last_content);
}
Intent data = new Intent();
setResult(2, data);
finish();
}
});
btn_cancel = (Button) findViewById(R.id.btn_cancel);
btn_cancel.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
finish();
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// TODO Auto-generated method stub
super.onActivityResult(requestCode, resultCode, data);
// if (requestCode == 3 && resultCode == 4) {
// last_content=data.getStringExtra("data");
// Log.d("LAST_STRAING", last_content+"gvg");
// }
}
}七、其中，对ListView添加OnItemLongclicklistener，长点击之后会弹出一个dialog对话框提醒要不要删除该日志文件。
public boolean onItemLongClick(AdapterView arg0, View arg1, int arg2,
long arg3) {
final int n=arg2;
Builder builder = new AlertDialog.Builder(this);
builder.setTitle("删除该日志");
builder.setMessage("确认删除吗？");
builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
String content = listview.getItemAtPosition(n) + "";
String content1 = content.substring(content.indexOf("=") + 1,
content.indexOf(","));
Cursor c = dbread.query("note", null, "content=" + "'"
+ content1 + "'", null, null, null, null);
while (c.moveToNext()) {
String id = c.getString(c.getColumnIndex("_id"));
String sql_del = "update note set content='' where _id="
+ id;
dbread.execSQL(sql_del);
RefreshNotesList();
}
}
});
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
builder.create();
builder.show();
return true;
}注意最后将返回值设为true，否则会和OnItemClickListener产生冲突。
附上长点击删除的效果。
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