AndroidStudio备忘录（简单）实现

AndroidStudio备忘录（简单）实现项⽬简介AndroidStudio环境下，备忘录（简单）的实现，功能有：添加,单个查询，删除全部内容，并可获取当前时间存储在SqlLite中。所⽤到的显⽰控件为ScrollView,EditText,TextView,ImageButton.图⽚展⽰⾸页添加页Acticity_main.xml代码展<?xmlversion="1.0"encoding="utf-8"?><?xmlversion="1.0"encoding="utf-8"?><LinearLayoutandroid="/apk/res/android"app="/apk/res-auto"tools="/tools"layout_width="match_parent"layout_height="match_parent"background="@drawable/backgroundone"orientation="vertical"context=".MainActivity"><LinearLayoutlayout_width="wrap_content"layout_height="wrap_content"layout_marginTop="15dp"layout_gravity="center_horizontal"><TextViewid="@+id/test"id="@+id/test"layout_width="wrap_content"layout_height="wrap_content"layout_gravity="center_horizontal"text="我的备忘录"textColor="#474646"textSize="45sp"textStyle="bold"/></LinearLayout><LinearLayoutlayout_width="wrap_content"layout_height="40dp"layout_gravity="center_horizontal"layout_marginLeft="10dp"orientation="horizontal"><EditTextid="@+id/view_select"layout_width="match_parent"layout_height="wrap_content"layout_gravity="center_horizontal"ems="13"hint="ft处可以查询数据！"inputType="textPersonName"/><ImageButtonid="@+id/btn_select"layout_width="wrap_content"layout_height="wrap_content"background="@android:color/transparent"srcCompat="@android:drawable/ic_menu_search"/></LinearLayout><ScrollViewlayout_width="match_parent"layout_height="490dp"layout_margin="5dp"layout_marginLeft="40dp"layout_marginRight="20dp"><LinearLayoutlayout_width="match_parent"layout_height="match_parent"orientation="vertical"><TextViewid="@+id/data"layout_width="match_parent"layout_height="match_parent"gravity="center_horizontal"textSize="20dp"></TextView></LinearLayout></ScrollView><ImageButtonid="@+id/btn_add"layout_width="80dp"layout_height="74dp"layout_marginLeft="300dp"background="@android:color/transparent"srcCompat="@drawable/add1"/></LinearLayout>Acativity_add.xml(添加)代码展⽰<?xmlversion="1.0"encoding="utf-8"?><LinearLayout android="/apk/res/android"app="/apk/res-auto"tools="/tools"layout_width="match_parent"layout_height="match_parent"orientation="vertical"context=".add"><LinearLayoutlayout_width="match_parent"layout_height="wrap_content"orientation="horizontal"><ImageButtonid="@+id/btn_back"layout_width="140dp"layout_height="60dp"background="@color/colorSilve"srcCompat="@android:drawable/ic_menu_revert"/><ImageButtonid="@+id/btn_finish"layout_width="130dp"layout_height="60dp"visibility="visible"background="@color/colorSilve"srcCompat="@android:drawable/checkbox_on_background"/><!--->改边颜⾊<ImageButtonid="@+id/btn_clear"layout_width="140dp"layout_height="60dp"visibility="visible"background="@color/colorSilve"srcCompat="@android:drawable/ic_delete"/></LinearLayout><LinearLayoutlayout_width="match_parent"layout_height="wrap_content"orientation="vertical"><TextViewid="@+id/now_time"layout_width="match_parent"layout_height="wrap_content"layout_marginTop="10dp"layout_marginBottom="10dp"textStyle="bold"textSize="20dp"></TextView></LinearLayout><LinearLayoutlayout_width="match_parent"layout_height="match_parent"><EditTextid="@+id/data_information"layout_width="match_parent"layout_height="match_parent"background="#00FFFFFF"gravity="start"textSize="25dp"hint="ft处写⽂章"textColor="#070507"></EditText></</LinearLayout></LinearLayout>MainActivity.java码展⽰packagecom.example.twicehomework;importandroidx.appcompat.app.AppCompatActivity;importandroid.content.Intent;importandroid.os.Bundle;importandroid.view.View;importandroid.widget.EditText;importandroid.widget.ImageButton;importandroid.widget.TextView;importandroid.widget.Toast;publicclassMainActivityextendsAppCompatActivity{privateImageButtonbtn_add;privateTextViewdata;privateImageButtonbtn_select;privateEditTextview_select;@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);data=findViewById(R.id.data);btn_select=findViewById(R.id.btn_select);view_select=findViewById(R.id.view_select);//跳转btn_add=(ImageButton)findViewById(R.id.btn_add);btn_add.setOnClickListener(newView.OnClickListener(){@OverridepublicvoidonClick(Viewv){Intentintent=newIntent();intent.setClass(MainActivity.this,add.class);startActivity(intent);}});/**页⾯传递值**/Intenti=getIntent();Stringget_data=i.getStringExtra("data");data.setText(get_data);//查询监听btn_select.setOnClickListener(newView.OnClickListener(){@OverridepublicvoidonClick(Viewv){Stringinput=view_select.getText().toString().trim();Stringget=data.getText().toString().trim();//判断查询信息输⼊是否为空，并返回值if(!input.isEmpty()){inta=get.indexOf(input);//内容第⼀次出现的位置//判断查询内容是否存在if(a!=-1){Stringfrontget.substring(0,a+1); //查询内容字段的位置的前⼀段数据截取Stringafterget.substring(a+1,get.length//查询内容字段的位置的的后⼀段数据截取inta1=front.lastIndexOf("2020");//前⼀段数据最后⼀次出现2020的位置intb1=after.indexOf("2020");//后⼀段数据第⼀次出现2020的位置Stringfront2;//传值位Stringafter2;//传值位//防⽌查询数据为第⼀位，出现错误if(a1==-1){front2=front;}else{Stringfront1=front.substring(a1,front.length());front2=front1;}//防⽌查询数据为最后⼀位,出现错误if(b1==-1){after2=after;}else{Stringafter1=after.substring(0,b1);after2=after1;}showMsg(front2+after2);//显⽰查询结果信息}else{showMsg("⽆匹配数据");}}else{showMsg("请输⼊查询的数据");}}});}//显⽰提⽰消息privatevoidshowMsg(Stringmsg){Toast.makeText(this,msg,Toast.LENGTH_SHORT).show();}}add.java代码展⽰packagepackagecom.example.twicehomework;importandroidx.annotation.Nullable;importandroidx.appcompat.app.AppCompatActivity;importandroid.content.ContentValues;importandroid.content.Context;importandroid.content.Intent;importandroid.database.Cursor;importandroid.database.sqlite.SQLiteDatabase;importandroid.database.sqlite.SQLiteOpenHelper;importandroid.os.Bundle;importandroid.view.View;importandroid.widget.EditText;importandroid.widget.ImageButton;importandroid.widget.TextView;importandroid.widget.Toast;importjava.text.SimpleDateFormat;importjava.util.Date;publicclassaddextendsAppCompatActivity{privateImageButtonbtn_back//返回按钮privateImageButtonbtn_finish;//完成按钮privateImageButtonbtn_clear;//清楚所有数据按钮privateTextViewnow_time;//当前时间privateEditTextdata_information;//存储数据//与数据库操作相关的成员变量privateMyDbHelpermyDbHelper;//数据库帮助类privateSQLiteDatabasedb;//数据库类privateContentValuesvalues;//数据表的⼀些参数privatestaticfinalStringmTablename="mymemo";//数据表的名称@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_add);//建⽴联系btn_back=findViewById(R.id.btn_back);data_information=findViewById(R.id.data_information);now_time=findViewById(R.id.now_time);btn_finish=findViewById(R.id.btn_finish);btn_clear=findViewById(R.id.btn_clear);//初始化数据库⼯具类实例myDbHelper=newMyDbHelper(this);//获取⼿机当前时间SimpleDateFormatsimpleDateFormat=newSimpleDateFormat("yyyy-MM-ddHH:mm:ss");Datedate=newDate(System.currentTimeMillis());finalStringstr_time=simpleDateFormat.format(date);now_time.setText(str_time);//返回主界⾯btn_back.setOnClickListener(newView.OnClickListener(){@OverridepublicvoidonClick(Viewv){Intentintent=newIntent();intent.setClass(add.this,MainActivity.class);startActivity(intent);queryData();}});//完成并执⾏添加操作btn_finish.setOnClickListener(newView.OnClickListener(){@OverridepublicvoidonClick(Viewv){Stringinput=data_information.getText().toString().trim();if(input.isEmpty()){showMsg("请输⼊要记录的内容");}else{addData(str_time.trim(),input);finish();queryData();}}});btn_clear.setOnClickListener(newView.OnClickListener(){@OverridepublicvoidonClick(Viewv){clearData();showMsg("数据清楚完毕");}});}//添加数据⽅法privatevoidaddData(Stringnow_time,Stringdata_information){db=myDbHelper.getWritableDatabase();values=newContentValues();values.put("now_time",now_time);values.put("information",data_information);db.insert(mTablename,null,values);showMsg("添加成功");}//清空所有数据的⽅法privatevoidclearData(){db=myDbHelper.getWritableDatabase();db.delete(mTablename,null,null);StringsrtResult="";Intentintent=newIntent(add.this,MainActivity.class);intent.putExtra("data",srtResult);startActivity(intent);showMsg("已经全部清空");}//显⽰消息⽅法privatevoidshowMsg(Stringmsg){Toast.makeText(this,msg,Toast.LENGTH_SHORT).show();}//查询⽅法privatevoidqueryData(){db=myDbHelper.getReadableDatabase();Cursorcursor=db.query(mTablename,null,null,null,null,null,null);StringsrtResult="";while(cursor.moveToNext()){srtResult+="\n"+cursor.getString(1);srtResult"\ncursor.getString(2);srtResult"\n";}Intentintent=newIntent(add.this,MainActivity.class);intent.putExtra("data",srtResult);startActivity(intent);}/****sqllite***/classMyDbHelperextendsSQLiteOpenHelper