安卓绿豆通讯录

概述activity_main.xml<?xmlversion="1.0"encoding="utf-8"?><RelativeLayoutxmlns:android="http://schemas.android.com/apkes/android"xmlns:tools="http://schemas.android.comools"android:layout_widt

activity_main.xml

<?xml version="1.0" enCoding="utf-8"?><relativeLayout xmlns:androID="http://schemas.androID.com/apk/res/androID"    xmlns:tools="http://schemas.androID.com/tools"    androID:layout_wIDth="match_parent"    androID:layout_height="match_parent"    androID:background="@drawable/bg"    androID:paddingBottom="16dp"    androID:paddingleft="16dp"    androID:paddingRight="16dp"    androID:paddingtop="16dp"    tools:context=".MainActivity">    <linearLayout        androID:ID="@+ID/ll_name"        androID:layout_wIDth="match_parent"        androID:layout_height="wrap_content"        androID:layout_above="@+ID/ll_phone"        androID:layout_alignleft="@+ID/ll_btn"        androID:layout_alignStart="@+ID/ll_btn">        <TextVIEw            androID:layout_wIDth="wrap_content"            androID:layout_height="wrap_content"            androID:textSize="18sp"            androID:text="姓  名 ：" />        <EditText            androID:ID="@+ID/et_name"            androID:layout_wIDth="match_parent"            androID:layout_height="wrap_content"            androID:textSize="16sp"            androID:hint="请输入姓名" />    </linearLayout>    <linearLayout        androID:layout_wIDth="match_parent"        androID:layout_height="wrap_content"        androID:ID="@+ID/ll_phone"        androID:layout_marginBottom="10dp"        androID:layout_above="@+ID/ll_btn"        androID:layout_alignleft="@+ID/ll_name"        androID:layout_alignStart="@+ID/ll_name">        <TextVIEw            androID:layout_wIDth="wrap_content"            androID:layout_height="wrap_content"            androID:textSize="18sp"            androID:text="电  话 ：" />        <EditText            androID:ID="@+ID/et_phone"            androID:layout_wIDth="match_parent"            androID:layout_height="wrap_content"            androID:textSize="16sp"            androID:hint="请输入手机号码" />    </linearLayout>    <linearLayout        androID:layout_wIDth="match_parent"        androID:layout_height="wrap_content"        androID:ID="@+ID/ll_btn"        androID:layout_centerVertical="true" >        <button            androID:ID="@+ID/btn_add"            androID:layout_wIDth="0dp"            androID:layout_height="wrap_content"            androID:layout_weight="1"            androID:textSize="18sp"            androID:background="#B9B9FF"            androID:layout_marginRight="2dp"            androID:text="添加" />        <button            androID:ID="@+ID/btn_query"            androID:layout_wIDth="0dp"            androID:layout_height="wrap_content"            androID:layout_weight="1"            androID:textSize="18sp"            androID:background="#DCB5FF"            androID:layout_marginRight="2dp"            androID:text="查询" />        <button            androID:ID="@+ID/btn_update"            androID:layout_wIDth="0dp"            androID:layout_height="wrap_content"            androID:layout_weight="1"            androID:textSize="18sp"            androID:background="#E6CAFF"            androID:layout_marginRight="2dp"            androID:text="修改" />        <button            androID:ID="@+ID/btn_delete"            androID:layout_wIDth="0dp"            androID:layout_height="wrap_content"            androID:layout_weight="1"            androID:textSize="18sp"            androID:background="#ACD6FF"            androID:text="删除" />    </linearLayout>    <TextVIEw        androID:ID="@+ID/tv_show"        androID:layout_wIDth="match_parent"        androID:layout_height="wrap_content"        androID:layout_margintop="25dp"        androID:layout_below="@+ID/ll_btn"        androID:textSize="20sp" /></relativeLayout>

MyHelper.java

package cn.itcast.directory;import androID.content.Context;import androID.database.sqlite.sqliteDatabase;import androID.database.sqlite.sqliteOpenHelper;import androIDx.annotation.NonNull;import androIDx.annotation.Nullable;public class MyHelper extends sqliteOpenHelper {    public MyHelper(Context context) {        super(context, "itcast.db", null, 1);    }    //当数据库第一次创建的时候执行    @OverrIDe    public voID onCreate(sqliteDatabase db) {        db.execsql("CREATE table information(_ID INTEGER PRIMARY KEY autoINCREMENT, name VARCHAR(20),  phone VARCHAR(20))");    }    @OverrIDe    public voID onUpgrade(sqliteDatabase db, int oldVersion, int newVersion) {    }}

MainActivity.java

package cn.itcast.directory;import androIDx.appcompat.app.AppCompatActivity;import androID.content.ContentValues;import androID.database.Cursor;import androID.database.sqlite.sqliteDatabase;import androID.os.Bundle;import androID.vIEw.VIEw;import androID.Widget.button;import androID.Widget.EditText;import androID.Widget.TextVIEw;import androID.Widget.Toast;import static cn.itcast.directory.R.*;public class MainActivity extends AppCompatActivity implements VIEw.OnClickListener {    private  MyHelper myHelper;    private EditText mEtname;    private EditText mEtPhone;    private TextVIEw mTvShow;    private button mBtnAdd;    private button mBtnquery;    private button mBtnUpdate;    private button mBtnDelete;    @OverrIDe    protected voID onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentVIEw(layout.activity_main);        myHelper = new MyHelper(this);        init(); //初始化控件    }    private voID init() {        mEtname = (EditText) findVIEwByID(ID.et_name);        mEtPhone = (EditText) findVIEwByID(ID.et_phone);        mTvShow = (TextVIEw) findVIEwByID(ID.tv_show);        mBtnAdd = (button) findVIEwByID(ID.btn_add);        mBtnquery = (button) findVIEwByID(ID.btn_query);        mBtnUpdate = (button) findVIEwByID(ID.btn_update);        mBtnDelete = (button) findVIEwByID(ID.btn_delete);        mBtnAdd.setonClickListener(this);        mBtnquery.setonClickListener(this);        mBtnUpdate.setonClickListener(this);        mBtnDelete.setonClickListener(this);    }    @OverrIDe    public voID onClick(VIEw v) {        String name;        String phone;        sqliteDatabase db;        ContentValues values;        switch (v.getID()) {            case R.ID.btn_add:      //添加数据                name = mEtname.getText().toString();                phone = mEtPhone.getText().toString();                db = myHelper.getWritableDatabase();//获取可读写sqliteDatabse对象                values = new ContentValues();       // 创建ContentValues对象                values.put("name", name);           // 将数据添加到ContentValues对象                values.put("phone", phone);                db.insert("information", null, values);                Toast.makeText(this, "信息已添加", Toast.LENGTH_SHORT).show();                db.close();                break;            case ID.btn_query:      //查询数据                db = myHelper.getReadableDatabase();                Cursor cursor = db.query("information", null, null, null, null,                        null, null);                if (cursor.getCount() == 0) {                    mTvShow.setText("");                    Toast.makeText(this, "没有数据", Toast.LENGTH_SHORT).show();                } else {                    cursor.movetoFirst();                    mTvShow.setText("name :  " + cursor.getString(1) +                            "  ；Tel :  " + cursor.getString(2));                }                while (cursor.movetoNext()) {                    mTvShow.append("\n" + "name :  " + cursor.getString(1) +                            "  ；Tel :  " + cursor.getString(2));                }                cursor.close();                db.close();                break;            case ID.btn_update:      //更新数据                db = myHelper.getWritableDatabase();                values = new ContentValues();       // 要修改的数据                values.put("phone", phone = mEtPhone.getText().toString());                db.update("information", values, "name=?",                        new String[]{mEtname.getText().toString()}); // 更新并得到行数                Toast.makeText(this, "信息已修改", Toast.LENGTH_SHORT).show();                db.close();                break;            case ID.btn_delete:      //删除数据                db = myHelper.getWritableDatabase();                db.delete("information", null, null);                Toast.makeText(this, "信息已删除", Toast.LENGTH_SHORT).show();                mTvShow.setText("");                db.close();                break;        }    }}

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