Day14作业

最新推荐文章于 2025-08-18 09:08:13 发布

原创最新推荐文章于 2025-08-18 09:08:13 发布 · 238 阅读

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本文详细介绍了一个基于Android平台的应用开发实例，包括MainActivity与WelcomeActivity的实现，以及使用SQLite进行数据库操作的方法。从UI组件的配置到数据的增删改查，全面展示了Android开发与数据库管理的技术要点。

作业

作业一

MainActivity

package com.example.homework;

import android.support.annotation.Nullable;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

import com.example.homework.Fragment_main.TestFragment;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private TextView textView_test;
    private TabLayout tabLayout;
    private ViewPager viewPager;

    private List<TestFragment> list = new ArrayList<>();
    private List<String> strList = new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initData();

        initView();

    }

    private void initData() {
        for (int i = 0; i < 3; i++) {
            list.add(new TestFragment());
            strList.add("第"+i+"个碎片");
        }
    }

    private void initView() {
        tabLayout = (TabLayout) findViewById(R.id.tab_layout);
        viewPager = (ViewPager) findViewById(R.id.view_pager);

        viewPager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {
            @Override
            public Fragment getItem(int i) {
                return list.get(i);
            }

            @Override
            public int getCount() {
                return list.size();
            }

            @Nullable
            @Override
            public CharSequence getPageTitle(int position) {
                return strList.get(position);
            }
        });

        tabLayout.setupWithViewPager(viewPager);
    }
}

欢迎页面

package com.example.homework;

import android.content.Intent;
import android.os.Handler;
import android.os.Message;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.example.homework.Fragment.FirstFragment;
import com.example.homework.Fragment.SecondFragment;
import com.example.homework.Fragment.ThirdFragment;

import java.util.ArrayList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

public class WelcomeActivity extends AppCompatActivity {

    private List<Fragment> fragmentList = new ArrayList<>();
    private ViewPager viewPager;
    private TextView textTime;
    private Button buttonToNext;

    private Timer timer;
    private int index = 3;
    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            if(msg.what == 1){
                textTime.setText("倒计时: "+index+"秒");
                index--;
                if(index == -1){
                    timer.cancel();
                    Intent intent = new Intent(WelcomeActivity.this, MainActivity.class);
                    startActivity(intent);
                    finish();
                }
            }
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_welcome);
        //初始化数据源
        initData();
        //初始化控件
        initView();
    }

    private void initData() {
        fragmentList.add(new FirstFragment());
        fragmentList.add(new SecondFragment());
        fragmentList.add(new ThirdFragment());

    }

    private void initView() {
        viewPager = findViewById(R.id.view_page);
        textTime = (TextView) findViewById(R.id.text_time);
        buttonToNext = (Button) findViewById(R.id.button_toNext);

        //viewPager的适配器
        PagerAdapter();

        //viewPager的监听器
        PagerListener();
    }

    private void PagerListener() {
        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int i, float v, int i1) {

            }

            @Override
            public void onPageSelected(int i) {
                if(i == fragmentList.size()-1){
                    buttonToNext.setVisibility(View.VISIBLE);
                    textTime.setVisibility(View.VISIBLE);

                    timer = new Timer();
                    timer.schedule(new TimerTask() {
                        @Override
                        public void run() {
                            handler.sendEmptyMessage(1);
                        }
                    },0,1000);

                    buttonToNext.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            timer.cancel();
                            Intent intent = new Intent(WelcomeActivity.this, MainActivity.class);
                            startActivity(intent);
                            finish();
                        }
                    });
                }
            }

            @Override
            public void onPageScrollStateChanged(int i) {

            }
        });


    }

    private void PagerAdapter() {
        viewPager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {
            @Override
            public Fragment getItem(int i) {
                return fragmentList.get(i);
            }

            @Override
            public int getCount() {
                return fragmentList.size();
            }
        });
    }
}

还有6个Fragmet，Main和Welcome的就不写了

作业二数据库SQLite

MainActivity

package com.example.homework2;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private SQLiteDatabase db;

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

        //获取sqlOpenHelper对象
        SqlHelper sql = new SqlHelper(this, "person.db", null, 2);

        //打开读写可读可写，没有自动创建
         db = sql.getReadableDatabase();

    }


    public void insert(View view) {
        //原生增加
        String sql = "insert into student values(?,?,?)";
        //开启事务
        db.beginTransaction();
        for (int i = 0; i < 10; i++) {
            db.execSQL(sql,new Object[]{"小明",(i+1),"男"});
        }
        //开启成功
        db.setTransactionSuccessful();
        //结束事务
        db.endTransaction();
        //方法增加
        ContentValues contentValues = new ContentValues();
        contentValues.put("name","小明");
        contentValues.put("sex","男");
        contentValues.put("age",1);

        db.insert("student",null,contentValues);
    }

    public void update(View view) {

        //方法一
        String sql = "update student set name = ? where age = ?";
        db.execSQL(sql,new Object[]{"小王",1});

        //方法二
        ContentValues contentValues = new ContentValues();
        contentValues.put("name","小王");
        db.update("person",contentValues,"age = ?",new String[]{"1"});
    }

    public void select(View view) {

        //方法一
        Cursor cursor = db.rawQuery("select * from student", null);
        if(cursor != null){
            //同下
            while(cursor.moveToNext()){
                String name = cursor.getString(cursor.getColumnIndex("name"));
                String sex = cursor.getString(cursor.getColumnIndex("sex"));
                int age = cursor.getInt(cursor.getColumnIndex("age"));

                Toast.makeText(this, name+"-"+sex+"-"+age, Toast.LENGTH_SHORT).show();
            }
        }

        //方法二
        //首先获取游标
        Cursor student = db.query("student", null, null, null, null, null, null);
        //游标不为空则执行
        if(student != null){
            //游标遍历数据库
            while(student.moveToNext()){
                String name = student.getString(student.getColumnIndex("name"));
                String sex = student.getString(student.getColumnIndex("sex"));
                int age = student.getInt(student.getColumnIndex("age"));

                Toast.makeText(this, name+"-"+sex+"-"+age, Toast.LENGTH_SHORT).show();
            }

        }

    }

    public void delete(View view) {

        //方法一
        db.execSQL("delete from student where id = ?",new Object[]{1});

        //方法二
        db.delete("student","age = ?",new String[]{"1"});
    }
}

数据库 SqlHelper

package com.example.homework2;

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

public class SqlHelper extends SQLiteOpenHelper {


    public SqlHelper( Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table student(name varchar(20),age int, sex varchar(20))");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}