Android实战—答题系统的简单实现

Question：

package com.example.lenovo.exam;

/**
 * Created by lenovo on 2017/12/4.
 */
//保存从数据库中读取的记录
public class Question {
    public String question;
    public  String answerA;
    public String answerB;
    public String answerC;
    public String answerD;
    public int answer;
    public String explaination;
    public int ID ;
    //用户选择的答案
    public int selectedAnswer;
}

DBService:

使用android自带数据库 下载SQLite Database Browser对数据库进行操作
src main 文件夹下创建assests文件夹（此文件夹下的内容在应用被打包成apk时不会被压缩） （存放试题数据库）
在数据库启动时，将该数据库文件复制到数据库目录下

package com.example.lenovo.exam;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

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

/**
 * Created by lenovo on 2017/12/4.
 */
//连接数据库，并从数据库中获取所需数据
public class DBService {
    private SQLiteDatabase db;
    //在构造函数中打开指定数据库，并把它的引用指向db
    public DBService(){
        db=SQLiteDatabase.openDatabase("/data/data/com.example.lenovo.exam/databases/question.db" +
                "",null,SQLiteDatabase.OPEN_READWRITE);
    }
    //获取数据库中的问题
    public List getQuestion(){
        List list=new ArrayList();
        /*
               Cursor是结果集游标，用于对结果集进行随机访问,其实Cursor与JDBC中的ResultSet作用很相似。
             rawQuery()方法的第一个参数为select语句；第二个参数为select语句中占位符参数的值，如果select语句没有使用占位符，该参数可以设置为null。*/
        Cursor cursor =db.rawQuery("select * from question",null);
        if(cursor.getCount()>0){
            cursor.moveToFirst();//将cursor移动到第一个光标上
            int count=cursor.getCount();
            //将cursor中的每一条记录生成一个question对象，并将该question对象添加到list中
            for(int i=0;i

ExamActivity:

package com.example.lenovo.exam;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;

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

/**
 * Created by lenovo on 2017/12/4.
 */

public class ExamActivity extends Activity {

    private int count;
    private int current;
    private  boolean wrongMode;//标志变量，判断是否进入错题模式

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_exam);

        DBService dbService = new DBService();
        final List list = dbService.getQuestion();

        count = list.size();
        current = 0;
        wrongMode=false;//默认情况

        final TextView tv_question = findViewById(R.id.question);
        final RadioButton[] radioButtons = new RadioButton[4];
        radioButtons[0] = findViewById(R.id.answerA);
        radioButtons[1] = findViewById(R.id.answerB);
        radioButtons[2] = findViewById(R.id.answerC);
        radioButtons[3] = findViewById(R.id.answerD);
        Button btn_previous = findViewById(R.id.btn_previous);
        Button btn_next = findViewById(R.id.btn_next);
        final TextView tv_explaination = findViewById(R.id.explaination);
        final RadioGroup radioGroup = findViewById(R.id.radioGroup);
        //为控件赋值
        Question q = list.get(0);
        tv_question.setText(q.question);
        tv_explaination.setText(q.explaination);
        radioButtons[0].setText(q.answerA);
        radioButtons[1].setText(q.answerB);
        radioButtons[2].setText(q.answerC);
        radioButtons[3].setText(q.answerD);

        btn_next.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                if (current < count - 1) {//若当前题目不为最后一题，点击next按钮跳转到下一题；否则不响应
                    current++;
                    //更新题目
                    Question q = list.get(current);
                    tv_question.setText(q.question);
                    radioButtons[0].setText(q.answerA);
                    radioButtons[1].setText(q.answerB);
                    radioButtons[2].setText(q.answerC);
                    radioButtons[3].setText(q.answerD);
                    tv_explaination.setText(q.explaination);

                    //若之前已经选择过，则应记录选择
                    radioGroup.clearCheck();
                    if (q.selectedAnswer != -1) {
                        radioButtons[q.selectedAnswer].setChecked(true);
                    }

                }
                //错题模式的最后一题
                else if(current==count-1&& wrongMode==true){
                    new AlertDialog.Builder(ExamActivity.this)
                            .setTitle("提示")
                            .setMessage("已经到达最后一题，是否退出？")
                            .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialogInterface, int i) {
                                    ExamActivity.this.finish();
                                }
                            })
                            .setNegativeButton("取消",null)
                            .show();

                }
                else{
                    //当前题目为最后一题时，告知用户作答正确的数量和作答错误的数量，并询问用户是否要查看错题
                    final List  wrongList=checkAnswer(list);
                    //作对所有题目
                    if(wrongList.size()==0){
                        new AlertDialog.Builder(ExamActivity.this)
                                .setTitle("提示")
                                .setMessage("恭喜你全部回答正确！")
                                .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                                    @Override
                                    public void onClick(DialogInterface dialogInterface, int i) {
                                        ExamActivity.this.finish();
                                    }
                                }).show();

                    }
                    else
                        new AlertDialog.Builder(ExamActivity.this)
                                .setTitle("提示")
                                .setMessage("您答对了"+(list.size()-wrongList.size())+
                                        "道题目；答错了"+wrongList.size()+"道题目。是否查看错题？")
                                .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                                    @Override
                                    public void onClick(DialogInterface dialogInterface, int which) {

                                        //判断进入错题模式
                                        wrongMode=true;
                                        List newList=new ArrayList();
                                        //将错误题目复制到newList中
                                        for(int i=0;i< wrongList.size();i++){
                                            newList.add(list.get(wrongList.get(i)));
                                        }
                                        //将原来的list清空
                                        list.clear();
                                        //将错误题目添加到原来的list中
                                        for(int i=0;i 0)//若当前题目不为第一题，点击previous按钮跳转到上一题；否则不响应
                {
                    current--;
                    Question q = list.get(current);
                    tv_question.setText(q.question);
                    radioButtons[0].setText(q.answerA);
                    radioButtons[1].setText(q.answerB);
                    radioButtons[2].setText(q.answerC);
                    radioButtons[3].setText(q.answerD);
                    tv_explaination.setText(q.explaination);


                    //若之前已经选择过，则应记录选择
                    radioGroup.clearCheck();
                    if (q.selectedAnswer != -1) {
                        radioButtons[q.selectedAnswer].setChecked(true);
                    }

                }

            }
        });
        //选择选项时更新选择
        radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup radioGroup, int checkedId) {
                for (int i = 0; i < 4; i++) {
                    if (radioButtons[i].isChecked() == true) {
                        list.get(current).selectedAnswer = i;
                        break;
                    }
                }

            }
        });
    }

    /*
判断用户作答是否正确，并将作答错误题目的下标生成list,返回给调用者
 */
    private List checkAnswer(List list) {
        List wrongList = new ArrayList();
        for(int i=0;i

MainActivity:

package com.example.lenovo.exam;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;


import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        String DB_PATH = "/data/data/com.example.lenovo.exam/databases/";
        String DB_NAME = "question.db";
        //应用启动时，判断数据库是否存在，不存在则将提前打包好的数据库文件复制到数据库目录下
        //数据库目录不存在时，创建数据库目录
        if ((new File(DB_PATH + DB_NAME).exists()) == false) {
            File dir = new File(DB_PATH);
            if (!dir.exists()) {
                dir.mkdir();
            }
        }
//定义输入输出流，用于复制文件
        try {
            InputStream is = getBaseContext().getAssets().open(DB_NAME);
            OutputStream os = new FileOutputStream(DB_PATH + DB_NAME);
            byte[] buffer = new byte[1024];
            int length;
            while ((length = is.read(buffer)) > 0) {
                os.write(buffer, 0, length);
            }
            //刷新输出流，关闭输入输出流
            os.flush();
            os.close();
            os.close();


        } catch (IOException e) {
            e.printStackTrace();
        }


        Button btn = findViewById(R.id.button);
        btn.setOnClickListener(new View.OnClickListener()

        {
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, ExamActivity.class);
                startActivity(intent);


            }
        });


    }
}

运行截图