第五次安卓作业（计算器和增删改查）

<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=".MainActivity" >

<TextView
android:id="@+id/tv2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/et2"
android:layout_centerVertical="true"
android:gravity="center"
android:text="显示计算结果"
android:textStyle="italic" />
<EditText
android:id="@+id/et3"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/tv2"
android:layout_alignLeft="@+id/et1"
android:ems="10" >
<requestFocus />
</EditText>
<EditText
android:id="@+id/et1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/et3"
android:layout_alignLeft="@+id/tv1"
android:hint="请输入数值"
android:ems="10" />
<EditText
android:id="@+id/et2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/et1"
android:layout_alignLeft="@+id/tv1"
android:hint="请输入数值"
android:ems="10" />
<Button
android:id="@+id/sum"
android:layout_width="152dp"
android:layout_height="wrap_content"
android:editable="false"
android:text="+" />

<Button
android:id="@+id/reduce"
android:layout_width="152dp"
android:layout_height="wrap_content"
android:layout_toRightOf="@+id/sum"
android:text="-"
android:textSize="20sp" />
<Button
android:id="@+id/ride"
android:layout_width="152dp"
android:layout_height="wrap_content"
android:layout_below="@+id/sum"
android:text="X" />

<Button
android:id="@+id/except"
android:layout_width="152dp"
android:layout_height="wrap_content"
android:layout_below="@+id/reduce"
android:layout_toRightOf="@+id/ride"
android:text="/" />

</RelativeLayout>

package com.example.a;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
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 {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}

public void click(View v) {
TextView tv2 = (TextView) findViewById(R.id.tv2);
EditText et1 = (EditText) findViewById(R.id.et1);
EditText et2 = (EditText) findViewById(R.id.et2);

int num1,num2,result=0;
num1=Integer.parseInt(et1.getText().toString());
num2=Integer.parseInt(et2.getText().toString());

switch (v.getId()) {
case R.id.sum:
result=num1+num2;
break;
case R.id.reduce:
result=num1-num2;
break;
case R.id.ride:
result=num1*num2;
break;
case R.id.except:
result=num1/num2;
break;
}
tv2.setText(result+"");
}

}

增删改查：：

<?xml version="1.0" encoding="UTF-8"?>

<LinearLayout android:padding="16dp" android:orientation="vertical" android:background="@drawable/bg" android:layout_height="match_parent" android:layout_width="match_parent" xmlns:android="http://schemas.android.com/apk/res/android">

<LinearLayout android:layout_height="wrap_content" android:layout_width="match_parent" android:layout_marginTop="130dp">

<TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textSize="18sp" android:text="姓 名 ："/>

<EditText android:layout_height="wrap_content" android:layout_width="match_parent" android:textSize="16sp" android:hint="请输入姓名" android:id="@+id/et_name"/>

</LinearLayout>

-<LinearLayout android:layout_height="wrap_content" android:layout_width="match_parent" android:layout_marginBottom="10dp">

<TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textSize="18sp" android:text="年 龄："/>

<EditText android:layout_height="wrap_content" android:layout_width="match_parent" android:textSize="16sp" android:hint="输入年龄" android:id="@+id/et_age"/>

</LinearLayout>

-<LinearLayout android:layout_height="wrap_content" android:layout_width="match_parent">

<Button android:background="#B9B9FF" android:layout_height="wrap_content" android:layout_width="0dp" android:textSize="18sp" android:text="添加" android:id="@+id/btn_add" android:onClick="add" android:layout_weight="1" android:layout_marginRight="2dp"/>

<Button android:background="#DCB5FF" android:layout_height="wrap_content" android:layout_width="0dp" android:textSize="18sp" android:text="查询" android:id="@+id/btn_query" android:onClick="search" android:layout_weight="1" android:layout_marginRight="2dp"/>

<Button android:background="#E6CAFF" android:layout_height="wrap_content" android:layout_width="0dp" android:textSize="18sp" android:text="修改" android:id="@+id/btn_update" android:onClick="update" android:layout_weight="1" android:layout_marginRight="2dp"/>

<Button android:background="#ACD6FF" android:layout_height="wrap_content" android:layout_width="0dp" android:textSize="18sp" android:text="删除" android:id="@+id/btn_delete" android:onClick="delete" android:layout_weight="1"/>

</LinearLayout>

-<ScrollView android:layout_height="wrap_content" android:layout_width="match_parent">

<TextView android:layout_height="wrap_content" android:layout_width="match_parent" android:layout_marginTop="25dp" android:textSize="20sp" android:id="@+id/tv_show"/>

</ScrollView>

</LinearLayout>

package com.example.login_add;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}

@SuppressLint("WrongConstant")
public void add(View v) {
StuOpenHelper helper = new StuOpenHelper(this);
SQLiteDatabase db = helper.getWritableDatabase();
String name = ((EditText) findViewById(R.id.et_name)).getText()
.toString();
int age = Integer.parseInt(((EditText) findViewById(R.id.et_age))
.getText().toString());

// 原生sql操作,
// db.execSQL("insert into stuinfo (name,age) values('lisi',22)");
// db.execSQL("insert into stuinfo (name,age) values(?,?)",new
// Object[]{"kitty",30});
db.execSQL("insert into stuinfo (name,age) values(?,?)", new Object[] {
name, age });
Toast.makeText(this, "ok", 0).show();

}

public void delete(View view) {
StuOpenHelper helper = new StuOpenHelper(this);
SQLiteDatabase db = helper.getWritableDatabase();
db.execSQL("delete from stuinfo where _id=?", new Object[] { 2 });
Toast.makeText(this, "删除成功", 0).show();

}

@SuppressLint("WrongConstant")
public void update(View view) {
StuOpenHelper helper = new StuOpenHelper(this);
SQLiteDatabase db = helper.getWritableDatabase();
db.execSQL("update stuinfo set name=? where _id=?", new Object[] {
"micky", 3 });
Toast.makeText(this, "修改成功", 0).show();

}

public void search(View view) {
StuOpenHelper helper = new StuOpenHelper(this);
SQLiteDatabase db = helper.getWritableDatabase();
String s = "";
Cursor cursor = db.rawQuery("select * from stuinfo", null);
if (cursor.getCount() != 0) {

while (cursor.moveToNext()) {
s += cursor.getInt(0) + " " + cursor.getString(1) + " "
+ cursor.getInt(2) + " ";
}
}

// Toast.makeText(this, s, 0).show();
((TextView) (findViewById(R.id.tv_show))).setText(s);

}

}

package com.example.login_add;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class StuOpenHelper extends SQLiteOpenHelper {

public StuOpenHelper(Context context) {
super(context, "stu.db", null, 1);
// TODO Auto-generated constructor stub
}

@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("create table stuinfo(_id integer primary key autoincrement,name varchar(20),age integer)");

}

@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
// TODO Auto-generated method stub

}

}