作业10（qq增删改查）

package com.example.zsgc1;





import android.app.Activity;


import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
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;

public class MainActivity extends Activity implements View.OnClickListener {
     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(R.layout.activity_main);
            myHelper=new MyHelper(this);
            init();
        }
        private void init(){
            mEtName=(EditText)findViewById(R.id.et_name);  
            mEtPhone=(EditText)findViewById(R.id.et_phone);
            mTvShow=(TextView)findViewById(R.id.tv_show);
            mBtnAdd=(Button)findViewById(R.id.btn_add);
            mBtnQuery=(Button)findViewById(R.id.btn_query);
            mBtnUpdate=(Button)findViewById(R.id.btn_update);
            mBtnDelete=(Button)findViewById(R.id.btn_delete);
            mBtnAdd.setOnClickListener(this);
            mBtnQuery.setOnClickListener(this);
            mBtnUpdate.setOnClickListener(this);
            mBtnDelete.setOnClickListener(this);
        }
        public void onClick(View view){
            String name,phone;
            SQLiteDatabase db;
            ContentValues values;
            switch (view.getId()){
                case R.id.btn_add:
                    name=mEtName.getText().toString();
                    phone=mEtPhone.getText().toString();
                    db=myHelper.getWritableDatabase();
                    values=new ContentValues();
                    values.put("name",name);
                    values.put("phone",phone);
                    db.insert("information",null,values);
                    Toast.makeText(this,"信息已添加",Toast.LENGTH_LONG).show();
                    db.close();
                    break;
                case R.id.btn_query:
                    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_LONG).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 R.id.btn_update:
                    db=myHelper.getWritableDatabase();
                    values=new ContentValues();
                    values.put("phone",phone=mEtPhone.getText().toString());
                    db.update("information",values,"name=?",new String[]{mEtName.getText().toString()});
                    Toast.makeText(this,"信息已修改",Toast.LENGTH_LONG).show();
                    db.close();
                    break;
                case R.id.btn_delete:
                    db=myHelper.getWritableDatabase();
                    db.delete("information","name=?",new String[]{mEtName.getText().toString()});
                    Toast.makeText(this,"信息已删除",Toast.LENGTH_LONG).show();
                    mTvShow.setText("");
                    db.close();
                    break;
            }
        }
        class MyHelper extends SQLiteOpenHelper{
            public MyHelper(Context context){
                super(context,"itcast.db",null,1);
            }
            public void onCreate(SQLiteDatabase db){
                db.execSQL("CREATE TABLE information(_id INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR(20),phone VARCHAR(20))");
            }
            public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion){

            }
        }
    }

<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.zsgc1.MainActivity" >

    <Button
        android:id="@+id/btn_add"
        android:layout_width="60dp"
        android:layout_height="40dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_marginBottom="121dp"
        android:text="添加" 
        android:onClick="CCC"/>

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
          android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
         android:layout_marginTop="150dp"
         android:layout_marginLeft="10dp"
        android:text="姓名" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
         android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_marginTop="220dp"
         android:layout_marginLeft="10dp"
        android:text="电话" />
    <EditText 
         android:id="@+id/et_name"
         android:layout_width="80dp"
        android:layout_height="wrap_content"
          android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_marginTop="130dp"
        android:layout_marginLeft="50dp"
        />
    <EditText 
         android:id="@+id/et_phone"
         android:layout_width="80dp"
        android:layout_height="wrap_content"
          android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_marginTop="200dp"
        android:layout_marginLeft="50dp"
        />

    <TextView
        android:id="@+id/tv_show"
        android:layout_width="150dp"
        android:layout_height="60dp"
        android:layout_alignParentBottom="true"
        android:layout_alignRight="@+id/button3"
        android:layout_marginBottom="55dp"
        android:layout_marginRight="23dp"
        android:text="" />

    <Button
        android:id="@+id/btn_query"
        android:layout_width="60dp"
        android:layout_height="40dp"
        android:layout_alignBaseline="@+id/btn_delete"
        android:layout_alignBottom="@+id/btn_delete"
        android:layout_toRightOf="@+id/btn_add"
        android:onClick="CCC"
        android:text="查询" />

    <Button
        android:id="@+id/btn_update"
        android:layout_width="60dp"
        android:layout_height="40dp"
        android:layout_alignBaseline="@+id/btn_query"
        android:layout_alignBottom="@+id/btn_query"
        android:layout_toRightOf="@+id/btn_query"
        android:onClick="CCC"
        android:text="修改" />

    <Button
        android:id="@+id/btn_delete"
        android:layout_width="60dp"
        android:layout_height="40dp"
        android:layout_alignBaseline="@+id/btn_add"
        android:layout_alignBottom="@+id/btn_add"
        android:layout_toRightOf="@+id/btn_update"
        android:onClick="CCC"
        android:text="删除" />

</RelativeLayout>