android开发的第一个app--GeoQuiz

Posted 2020-10-07

android开发是什么

　　Android开发是指android平台上应用的制作，Android早期由“Android之父”之称的Andy Rubin创办，Google于2005年并购了成立仅22个月的高科技企业Android，展开了短信、手机检索、定位等业务，以Java为编程语言，使接口到功能，都有层出不穷的变化。

此时此刻的感受

　　第一次写博客，感觉很奇妙，想了好久，还没有思路，到底写什么呢？仍记得，初高中写作文时，假如对文题没有头绪，就会选择编个故事，把自己当作其中的主角，想其所想，悟其所悟，体会其中的冷暖寒凉，然后一篇1000字的文章就写完了。这个时候，想着想着，渐渐有所感悟。博客记录的是一个程序员进行项目开发的所思所悟，这个贵在积累，每天一点点，既是对自己的总结又能将自己的经历与网友共勉。所以现在想来，博客也并没有那么难了，因为这是为自己书写的。

GeoQuiz的项目开发历程

创建Android项目

注意：

1、选择合适的SDK版本

2、注意子类名的Activity后缀，这是种规范的命名方式

用户界面设计

1、在XML文件（activity_quiz.xml）中定义组件，为按钮添加资源ID

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical">

    <TextView
        android:id="@+id/question_text_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="24dp" />
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <Button
            android:id="@+id/true_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/true_button"/>
        <Button
            android:id="@+id/false_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/false_button"/>

    </LinearLayout>
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
        <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/prev_button"
        android:text="@string/prev_button"/>
        <Button
        android:id="@+id/next_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/next_button"/>

    </LinearLayout>
    <Button
        android:id="@+id/cheat_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|center_horizontal"
        android:text="@string/cheat_button"/>

</LinearLayout>

 

2、视图层级结构

LinearLayout有两个子组件：TextView、LinearLayout。

若作为子组件的LinearLayout，还自带两个button组件。

组件的俩属性：match_parent、wrap_content

 

从布局XML到视图对象

1、引用组件，为TRUE、FALSE按钮设置监听器、创建提示消息

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG,"onCreate(Bundle)called");
        setContentView(R.layout.activity_quiz);

        if(savedInstanceState !=null){
            mCurrentIndex = savedInstanceState.getInt(KEY_INDEX,0);
        }

        mQuestionTextView = (TextView) findViewById(R.id.question_text_view);

        mTrueButton = (Button) findViewById(R.id.true_button);
        mTrueButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                Toast.makeText(QuizActivity.this,R.string.incorrect_toast,Toast.LENGTH_SHORT).show();
                checkAnswer(true);
            }
        });
        mFalseButton = (Button) findViewById(R.id.false_button);
        mFalseButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                Toast.makeText(QuizActivity.this,R.string.correct_toast,Toast.LENGTH_SHORT).show();
                checkAnswer(false);
            }
        });

2、接着可以尝试运行应用，界面图用最终的啦

注意：安卓手机首次连接时，手机需要在开发者选项，找到USB调试按钮并开启，手机连接也换成传送文件，并且注意点击手机上的提示信息，正确安装app

 

 

以小见大，融会贯通，实现app功能的完善与创新

1、Android与MVC设计模式

2、activity的生命周期

3、Android应用的调试

4、第二个activity

 

下面分别是各项的完整代码，仅供参考

CheatActivity

package edu.niit.software.geoquiz;

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

public class CheatActivity extends AppCompatActivity {

    private static final String EXTRA_ANSWER_IS_TRUE="edu.niit.software.geoquiz.answer_is_true";
    private static final String EXTRA_ANSWER_SHOWN = "edu.niit.software.geoquiz.answer_shown";
    private boolean mAnswerIsTrue;

    private TextView mAnswerTextView;
    private Button mShowAnswerButton;

    public static Intent newIntent(Context packageContext , boolean answerIsTrue){
        Intent intent = new Intent(packageContext,CheatActivity.class);
        intent.putExtra(EXTRA_ANSWER_IS_TRUE,answerIsTrue);
        return intent;
    }

    public static boolean wasAnswerShown(Intent result){
        return result.getBooleanExtra(EXTRA_ANSWER_SHOWN,false);
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_cheat);

        mAnswerIsTrue = getIntent().getBooleanExtra(EXTRA_ANSWER_IS_TRUE,false);

        mAnswerTextView = (TextView) findViewById(R.id.answer_text_view);

        mShowAnswerButton = (Button) findViewById(R.id.show_answer_button);
        mShowAnswerButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                if(mAnswerIsTrue){
                    mAnswerTextView.setText(R.string.true_button);
                }else {
                    mAnswerTextView.setText(R.string.false_button);
                }
                setAnswerShownResult(true);
            }
        });
    }
    private void setAnswerShownResult(boolean isAnswerShown){
        Intent data = new Intent();
        data.putExtra(EXTRA_ANSWER_SHOWN,isAnswerShown);
        setResult(RESULT_OK,data);
    }
}

　　

 Question

package edu.niit.software.geoquiz;

/**
 * Created by 666 on 2017/9/4.
 */

public class Question {
    private int mTextResId;
    private boolean mAnswerTrue;

    public Question(int textResId,boolean answertrue){
        mTextResId = textResId;
        mAnswerTrue = answertrue;
    }

    public int getTextResId() {
        return mTextResId;
    }

    public void setTextResId(int textResId) {
        mTextResId = textResId;
    }

    public boolean isAnswerTrue() {
        return mAnswerTrue;
    }

    public void setAnswerTrue(boolean answerTrue) {
        mAnswerTrue = answerTrue;
    }
}

　QuizActivity

package edu.niit.software.geoquiz;

import android.app.Activity;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class QuizActivity extends AppCompatActivity {
    private Button mTrueButton;
    private Button mFalseButton;
    private Button mNextButton;
    private Button mPrevButton;
    private Button mCheatButton;
    private TextView mQuestionTextView;
    private static final String TAG = "QuizActivity";
    private static final String KEY_INDEX = "index";

    private static final int REQUEST_CODE_CHEAT = 0;

    private Question[] mQuestionBank = new Question[]{
            new Question(R.string.question_australia ,true),
            new Question(R.string.question_oceans,true),
            new Question(R.string.question_mideast,false),
            new Question(R.string.question_africa,false),
            new Question(R.string.question_americas,true),
            new Question(R.string.question_asia,true)
    };

    private int mCurrentIndex=0;
    private boolean mIsCheater;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG,"onCreate(Bundle)called");
        setContentView(R.layout.activity_quiz);

        if(savedInstanceState !=null){
            mCurrentIndex = savedInstanceState.getInt(KEY_INDEX,0);
        }

        mQuestionTextView = (TextView) findViewById(R.id.question_text_view);

        mTrueButton = (Button) findViewById(R.id.true_button);
        mTrueButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                //Toast.makeText(QuizActivity.this,R.string.incorrect_toast,Toast.LENGTH_SHORT).show();
                checkAnswer(true);
            }
        });
        mFalseButton = (Button) findViewById(R.id.false_button);
        mFalseButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
               // Toast.makeText(QuizActivity.this,R.string.correct_toast,Toast.LENGTH_SHORT).show();
                checkAnswer(false);
            }
        });
        mNextButton = (Button) findViewById(R.id.next_button);
        mNextButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                mCurrentIndex = (mCurrentIndex+1) % mQuestionBank.length;
                mIsCheater = false;
                updateQuestion();
            }
        });

        mPrevButton = (Button) findViewById(R.id.prev_button);
        mPrevButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                mCurrentIndex = (mCurrentIndex-1) % mQuestionBank.length;
                updateQuestion();
            }
        });

        mCheatButton = (Button) findViewById(R.id.cheat_button);
        mCheatButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                //Intent intent = new Intent(QuizActivity.this , CheatActivity.class);
                boolean answerIsTrue = mQuestionBank[mCurrentIndex].isAnswerTrue();
                Intent intent = CheatActivity.newIntent(QuizActivity.this,answerIsTrue);
                //startActivity(intent);
                startActivityForResult(intent,REQUEST_CODE_CHEAT);
            }
        });
        updateQuestion();

    }

    @Override
    public void onStart(){
        super.onStart();
        Log.d(TAG,"onStart() called");
    }
    @Override
    public void onResume(){
        super.onResume();
        Log.d(TAG,"onResume() called");
    }
    @Override
    public void onPause(){
        super.onPause();
        Log.d(TAG,"onPause() called");
    }
    @Override
    public void onSaveInstanceState(Bundle savedInstanceState){
        super.onSaveInstanceState(savedInstanceState);
        Log.i(TAG,"onSaveInstanceState");
        savedInstanceState.putInt(KEY_INDEX,mCurrentIndex);
    }
    @Override
    public void onStop(){
        super.onStop();
        Log.d(TAG,"onStop() called");
    }
    @Override
    public void onDestroy(){
        super.onDestroy();
        Log.d(TAG,"onDestroy() called");
    }

    private void updateQuestion(){
        int question = mQuestionBank[mCurrentIndex].getTextResId();
        mQuestionTextView.setText(question);
    }

    private void checkAnswer(boolean userPressedTrue){
        boolean answerIsTrue = mQuestionBank[mCurrentIndex].isAnswerTrue();
        int messageResId = 0;
        if(mIsCheater){
            messageResId = R.string.judgment_toast;
        }else {
            if (userPressedTrue == answerIsTrue)
            {
                messageResId = R.string.correct_toast;
            } else {
                messageResId = R.string.incorrect_toast;
            }
        }
        Toast.makeText(this,messageResId,Toast.LENGTH_SHORT).show();
    }

    protected void onActivityResult(int requestCode , int resultCode , Intent data){
        if(resultCode != Activity.RESULT_OK){
            return;
        }
        if(requestCode == REQUEST_CODE_CHEAT){
            if(data == null){
                return;
            }
            mIsCheater = CheatActivity.wasAnswerShown(data);
        }
    }
}

strings

<resources>
    <string name="app_name">GeoQuiz</string>
    <string name="question_australia">堪培拉是澳大利亚的首都 </string>
    <string name="question_oceans">太平洋比大西洋大</string>
    <string name="question_mideast">苏伊士运河连接着红海和印度洋</string>
    <string name="question_africa">尼罗河流域在埃及</string>
    <string name="question_americas">亚马逊河是美国最长的河</string>
    <string name="question_asia">贝加尔湖是世界上最古老最深的淡水湖</string>
    <string name="true_button">TRUE</string>
    <string name="false_button">FALSE</string>
    <string name="next_button">Next</string>
    <string name="prev_button">Prev</string>
    <string name="correct_toast">Correct!</string>
    <string name="incorrect_toast">Incorrect!</string>
    <string name="warning_text">Are you sure you want to do this?</string>
    <string name="show_answer_button">Show Answer</string>
    <string name="cheat_button">Cheat!</string>
    <string name="judgment_toast">Cheating is wrong</string>
</resources>

　　

　　大体上就这么多，其中还遇到了一个麻烦，就是完成了快好的时候，被我一个不小心，全部删掉了，撤回不成，所以我又重写了一篇，如果其中有些许问题，望君海涵。