13518219792
這篇文章將為大家詳細(xì)講解有關(guān)android中l(wèi)istview與SQLite結(jié)合如何實(shí)現(xiàn)記事本功能，小編覺(jué)得挺實(shí)用的，因此分享給大家做個(gè)參考，希望大家閱讀完這篇文章后可以有所收獲。
android記事本的demo在網(wǎng)上一搜一大堆，但是大神寫(xiě)的demo往往功能太多導(dǎo)致新手難以著手，很難啃得動(dòng)；而一些新手寫(xiě)的demo又往往是東拼西湊，代碼很多都是copy的別人的，直接放在項(xiàng)目里面用，也不知道代碼有什么作用。往往代碼特別丑，重復(fù)性的代碼也比較多。
筆者近期學(xué)到此處，自己理解之后也還是打算寫(xiě)個(gè)demo供新手學(xué)習(xí)一下。代碼說(shuō)不上優(yōu)雅，但在筆者看來(lái)已經(jīng)盡力去讓人容易理解了。
為了便于新手學(xué)習(xí)，在此也是羅列一下涉及的知識(shí)點(diǎn)：
1、SQLite的基本使用，增刪查改
2、listview，adapeter的基本使用
3、activity生命周期
4、intent、bundle傳遞參數(shù)
5、AlertDialog的基本使用
另外還有一些零碎知識(shí)點(diǎn)都可以百度到。
遇到的問(wèn)題：
SQlite有個(gè)問(wèn)題，就是主鍵不能夠自動(dòng)排序。比如說(shuō)主鍵id為1 2 3 4，共4條記錄。現(xiàn)在刪除2 3，還剩下1 4記錄，當(dāng)再次插入時(shí)，id會(huì)變成5，而不是2.假設(shè)在初始4條記錄的基礎(chǔ)上，把這4條記錄全都刪掉，再次插入時(shí)，得到的id是5.
筆者在這點(diǎn)上也是花了比較久的時(shí)間，原本為了精簡(jiǎn)代碼，想法是用listview中的arg2直接通過(guò)數(shù)據(jù)庫(kù)記錄的id進(jìn)行操作，但是由于SQLite的這個(gè)問(wèn)題，所以這種方法就有問(wèn)題了。
最終，筆者采用的是內(nèi)容搜索的方法，從listview的每個(gè)item中獲取內(nèi)容，然后到數(shù)據(jù)庫(kù)中通過(guò)內(nèi)容搜索該記錄，最后對(duì)其進(jìn)行操作。
效果：
MainActivity：
import android.app.Activity;
import android.app.AlertDialog.Builder;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
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 java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MainActivity extends Activity implements
OnItemClickListener, OnItemLongClickListener {
private ListView listview;
private SimpleAdapter simple_adapter;
private List> dataList;
private Button addNote;
private TextView tv_content;
private NoteDateBaseHelper DbHelper;
private SQLiteDatabase DB;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
InitView();
}
//在activity顯示的時(shí)候更新listview
@Override
protected void onStart() {
super.onStart();
RefreshNotesList();
}
private void InitView() {
tv_content = (TextView) findViewById(R.id.tv_content);
listview = (ListView) findViewById(R.id.listview);
dataList = new ArrayList>();
addNote = (Button) findViewById(R.id.btn_editnote);
DbHelper = new NoteDateBaseHelper(this);
DB = DbHelper.getReadableDatabase();
listview.setOnItemClickListener(this);
listview.setOnItemLongClickListener(this);
addNote.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
Intent intent = new Intent(MainActivity.this, noteEdit.class);
Bundle bundle = new Bundle();
bundle.putString("info", "");
bundle.putInt("enter_state", 0);
intent.putExtras(bundle);
startActivity(intent);
}
});
}
//刷新listview
public void RefreshNotesList() {
//如果dataList已經(jīng)有的內(nèi)容，全部刪掉
//并且更新simp_adapter
int size = dataList.size();
if (size > 0) {
dataList.removeAll(dataList);
simple_adapter.notifyDataSetChanged();
}
//從數(shù)據(jù)庫(kù)讀取信息
Cursor cursor = DB.query("note", null, null, null, null, null, null);
startManagingCursor(cursor);
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);
}
simple_adapter = new SimpleAdapter(this, dataList, R.layout.item,
new String[]{"tv_content", "tv_date"}, new int[]{
R.id.tv_content, R.id.tv_date});
listview.setAdapter(simple_adapter);
}
// 點(diǎn)擊listview中某一項(xiàng)的點(diǎn)擊監(jiān)聽(tīng)事件
@Override
public void onItemClick(AdapterView arg0, View arg1, int arg2, long arg3) {
//獲取listview中此個(gè)item中的內(nèi)容
String content = listview.getItemAtPosition(arg2) + "";
String content1 = content.substring(content.indexOf("=") + 1,
content.indexOf(","));
Intent myIntent = new Intent(MainActivity.this, noteEdit.class);
Bundle bundle = new Bundle();
bundle.putString("info", content1);
bundle.putInt("enter_state", 1);
myIntent.putExtras(bundle);
startActivity(myIntent);
}
// 點(diǎn)擊listview中某一項(xiàng)長(zhǎng)時(shí)間的點(diǎn)擊事件
@Override
public boolean onItemLongClick(AdapterView arg0, View arg1, final int arg2,
long arg3) {
Builder builder = new Builder(this);
builder.setTitle("刪除該日志");
builder.setMessage("確認(rèn)刪除嗎？");
builder.setPositiveButton("確定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
//獲取listview中此個(gè)item中的內(nèi)容
//刪除該行后刷新listview的內(nèi)容
String content = listview.getItemAtPosition(arg2) + "";
String content1 = content.substring(content.indexOf("=") + 1,
content.indexOf(","));
DB.delete("note", "content = ?", new String[]{content1});
RefreshNotesList();
}
});
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
builder.create();
builder.show();
return true;
} NoteDateBaseHelper:
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class NoteDateBaseHelper extends SQLiteOpenHelper {
public static final String CreateNote = "create table note ("
+ "id integer primary key autoincrement, "
+ "content text , "
+ "date text)";
public NoteDateBaseHelper(Context context) {
super(context, "note", null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CreateNote);
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
// TODO Auto-generated method stub
}
}noteEdit：
import android.app.Activity;
import android.content.ContentValues;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import java.text.SimpleDateFormat;
import java.util.Date;
public class noteEdit extends Activity implements OnClickListener {
private TextView tv_date;
private EditText et_content;
private Button btn_ok;
private Button btn_cancel;
private NoteDateBaseHelper DBHelper;
public int enter_state = 0;//用來(lái)區(qū)分是新建一個(gè)note還是更改原來(lái)的note
public String last_content;//用來(lái)獲取edittext內(nèi)容
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.edit);
InitView();
}
private void InitView() {
tv_date = (TextView) findViewById(R.id.tv_date);
et_content = (EditText) findViewById(R.id.et_content);
btn_ok = (Button) findViewById(R.id.btn_ok);
btn_cancel = (Button) findViewById(R.id.btn_cancel);
DBHelper = new NoteDateBaseHelper(this);
//獲取此時(shí)時(shí)刻時(shí)間
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");
String dateString = sdf.format(date);
tv_date.setText(dateString);
//接收內(nèi)容和id
Bundle myBundle = this.getIntent().getExtras();
last_content = myBundle.getString("info");
enter_state = myBundle.getInt("enter_state");
et_content.setText(last_content);
btn_cancel.setOnClickListener(this);
btn_ok.setOnClickListener(this);
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.btn_ok:
SQLiteDatabase db = DBHelper.getReadableDatabase();
// 獲取edittext內(nèi)容
String content = et_content.getText().toString();
// 添加一個(gè)新的日志
if (enter_state == 0) {
if (!content.equals("")) {
//獲取此時(shí)時(shí)刻時(shí)間
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");
String dateString = sdf.format(date);
//向數(shù)據(jù)庫(kù)添加信息
ContentValues values = new ContentValues();
values.put("content", content);
values.put("date", dateString);
db.insert("note", null, values);
finish();
} else {
Toast.makeText(noteEdit.this, "請(qǐng)輸入你的內(nèi)容！", Toast.LENGTH_SHORT).show();
}
}
// 查看并修改一個(gè)已有的日志
else {
ContentValues values = new ContentValues();
values.put("content", content);
db.update("note", values, "content = ?", new String[]{last_content});
finish();
}
break;
case R.id.btn_cancel:
finish();
break;
}
}
}activity_main:
