android简单记事本

android简单记事本

近段学习数据存储写个小程序，简单记事本，实现点击查看删除，添加保存。闲话不多说直接步入正题。
一、上图看着更直观。
1、这是该程序的主界面。上边是一个Button，下边是ListView显示记录的笔记

2、 点击添加按钮显示的界面，非常简单，输入，保存，取消

3、 这是点击主界面笔记后的显示，笔记，删除，返回

二、下边开始实现阶段：

1》先写布局文件

1、主布局文件activity_main.xml
一个添加按钮，一个ListView，代码如下：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical">    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal">        <Button            android:id="@+id/main_add"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:text="添加"/>    </LinearLayout>    <ListView        android:id="@+id/main_list"        android:layout_width="match_parent"        android:layout_height="wrap_content"/></LinearLayout>

2、点击添加之后的跳转界面add_list.xml
上边是一个EditText，下边是两个按钮保存和删除

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical">    <EditText        android:id="@+id/add_etv"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="1"        android:background="@null"        android:gravity="top"        android:hint="记 录 点 滴，改 变 生 活" />    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_marginBottom="5dp"        android:gravity="center"        android:orientation="horizontal">        <Button            android:id="@+id/add_save"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="保存" />        <Button            android:id="@+id/add_delete"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginLeft="80dp"            android:text="取消" />    </LinearLayout></LinearLayout>

3、点击主界面的笔记跳转的界面，进行查看或者删除。select.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical">    <TextView        android:id="@+id/s_tv"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:layout_weight="1" />    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:orientation="horizontal">        <Button            android:id="@+id/s_delete"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_weight="1"            android:text="删除" />        <Button            android:id="@+id/s_back"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_weight="1"            android:text="返回" />    </LinearLayout></LinearLayout>

4、记录笔记显示在主界面的布局文件。list.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="100dp"        android:gravity="center_vertical"        android:orientation="vertical">        <TextView            android:id="@+id/list_content"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="tv" />        <TextView            android:id="@+id/list_time"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="tv" />    </LinearLayout></LinearLayout>

2》不同功能的类文件
1、建NotesDB.class文件用来建表写入数据类型

package com.example.guo.my_account;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;public class NotesDB extends SQLiteOpenHelper {    public static final String TABLE_NAME = "notes";    public static final String CONTENT = "content";    public static final String ID = "_id";    public static final String TIME = "time";    public NotesDB(Context context) {        super(context, "notes", null, 1);    }    @Override    public void onCreate(SQLiteDatabase db) {        db.execSQL("create table " + TABLE_NAME + " (" + ID + " integer primary key autoincrement,"                + CONTENT + " text not null," + TIME + " text not null)");    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {    }}

2、建立自定义数据文件MyAdapter.class

package com.example.guo.my_account;import android.content.Context;import android.database.Cursor;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.LinearLayout;import android.widget.TextView;public class MyAdapter extends BaseAdapter {    private Context context;    private Cursor cursor;    private LinearLayout layout;    public MyAdapter(MainActivity context, Cursor cursor){        this.context = context;        this.cursor = cursor;    }    @Override    public int getCount() {        return cursor.getCount();    }    @Override    public Object getItem(int position) {        return cursor.getPosition();    }    @Override    public long getItemId(int position) {        return position;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        LayoutInflater inflater = LayoutInflater.from(context);        layout = (LinearLayout) inflater.inflate(R.layout.list,null);        TextView contenttv = (TextView) layout.findViewById(R.id.list_content);        TextView timetv = (TextView) layout.findViewById(R.id.list_time);        cursor.moveToPosition(position);        String content = cursor.getString(cursor.getColumnIndex("content"));        String time = cursor.getString(cursor.getColumnIndex("time"));        contenttv.setText(content);        timetv.setText(time);        return layout;    }}

3、建立添加数据文件Addcontent.class

package com.example.guo.my_account;import android.app.Activity;import android.content.ContentValues;import android.content.Intent;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.EditText;import java.util.Date;import java.text.SimpleDateFormat;public class Addcontent extends Activity implements View.OnClickListener {    private Button savebtn, deletebtn;    private EditText ettext;    private NotesDB notesDB;    private SQLiteDatabase dbWriter;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.add_list);        savebtn = (Button) findViewById(R.id.add_save);        deletebtn = (Button) findViewById(R.id.add_delete);        ettext = (EditText) findViewById(R.id.add_etv);        savebtn.setOnClickListener(this);        deletebtn.setOnClickListener(this);        notesDB = new NotesDB(this);        dbWriter = notesDB.getWritableDatabase();    }    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.add_save:                addDB();                finish();                break;            case R.id.add_delete:                finish();                break;        }    }    private void addDB() {        ContentValues cv = new ContentValues();        cv.put(NotesDB.CONTENT, ettext.getText().toString());        cv.put(NotesDB.TIME, getTime());        dbWriter.insert(NotesDB.TABLE_NAME, null, cv);    }    public String getTime() {        SimpleDateFormat format = new SimpleDateFormat("yyy年MM月dd日 HH:mm:ss");        Date curDate = new Date();        String str = format.format(curDate);        return str;    }}

4、建立修改删除文件Select.class

package com.example.guo.my_account;import android.app.Activity;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.TextView;public class SelectAct extends Activity implements View.OnClickListener {    private Button s_delete, s_back;    private TextView s_tv;    private NotesDB notesDB;    private SQLiteDatabase dbWriter;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.select);        s_back = (Button) findViewById(R.id.s_back);        s_delete = (Button) findViewById(R.id.s_delete);        s_tv = (TextView) findViewById(R.id.s_tv);        notesDB = new NotesDB(this);        dbWriter = notesDB.getWritableDatabase();        s_back.setOnClickListener(this);        s_delete.setOnClickListener(this);        s_tv.setText(getIntent().getStringExtra(NotesDB.CONTENT));    }    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.s_delete:                deleteDate();                finish();                break;            case R.id.s_back:                finish();                break;        }    }    private void deleteDate() {        dbWriter.delete(NotesDB.TABLE_NAME, "_id=" + getIntent().getIntExtra(NotesDB.ID, 0), null);    }}

5、MainActivity.class

package com.example.guo.my_account;import android.app.Activity;import android.content.Intent;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.View;import android.widget.AdapterView;import android.widget.Button;import android.widget.ListView;import java.util.Timer;public class MainActivity extends Activity implements View.OnClickListener {    private Button addbtn;    private ListView lv;    private Intent i;    private SQLiteDatabase dbReader;    private Cursor cursor;    private NotesDB notesDB;    private MyAdapter adapter;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initView();    }    private void initView() {        addbtn = (Button) findViewById(R.id.main_add);        lv = (ListView) findViewById(R.id.main_list);        addbtn.setOnClickListener(this);        notesDB = new NotesDB(this);        dbReader = notesDB.getReadableDatabase();        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {            @Override            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {                cursor.moveToPosition(position);                Intent i = new Intent(MainActivity.this, SelectAct.class);                i.putExtra(NotesDB.ID, cursor.getInt(cursor.getColumnIndex(NotesDB.ID)));                i.putExtra(notesDB.CONTENT, cursor.getString(cursor.getColumnIndex(NotesDB.CONTENT)));                i.putExtra(notesDB.TIME, cursor.getString(cursor.getColumnIndex(NotesDB.TIME)));                startActivity(i);            }        });    }    @Override    public void onClick(View v) {        i = new Intent(this, Addcontent.class);        startActivity(i);    }    private void selectDB() {        cursor = dbReader.query(NotesDB.TABLE_NAME, null, null, null, null, null, null);        adapter = new MyAdapter(this, cursor);        lv.setAdapter(adapter);    }    @Override    protected void onResume() {        super.onResume();        selectDB();    }}

3》不要忘了在AndroidManifest.xml文件中声明
代码如下

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.guo.my_account">    <application        android:allowBackup="true"        android:icon="@mipmap/ic_launcher"        android:label="@string/app_name"        android:supportsRtl="true"        android:theme="@android:style/Theme.Light.NoTitleBar">        <activity android:name=".MainActivity">            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>        <activity android:name=".Addcontent"/>        <activity android:name=".SelectAct"/>    </application></manifest>

自己写的，不是很简单实用，有声明不足的希望留言，会改进。Thanks.后边会上传源码，多多学习。