Android编程权威指南第3版 2.7 挑战练习：为 TextView 添加监听器

前言

本文参考《Android编程权威指南》第三版。
仅供学习，侵权即删。
如有不当之处,还望指正。
这是上一篇博客内容：Android编程权威指南第3版 1.11 挑战练习：定制 toast 消息

1. 题目描述

NEXT按钮不错，但如果用户单击应用的TextView文字区域（地理知识问题），也可以跳转到下一道题，用户体验会更好。
提示： TextView也是View的子类，因此和Button一样，可为TextView设置View.OnClickListener监听器。

2. Create New Project

首先新建一个项目。

3. MainActivity.java

package com.example.test3;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
     

    private Button mTrueButton;
    private Button mFalseButton;
    private Button mNextButton;
    private TextView mQuestionTextView;

    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;

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

        mQuestionTextView = (TextView) findViewById(R.id.question_text_view);
//        为 TextView 添加监听器
        mQuestionTextView.setOnClickListener(new View.OnClickListener(){
     
            @Override
            public void onClick(View view) {
     
                mCurrentIndex = (mCurrentIndex + 1) % mQuestionBank.length;
                updateQuestion();
            }
        });
        updateQuestion();
        mTrueButton = (Button) findViewById(R.id.true_button);
        mTrueButton.setOnClickListener(new View.OnClickListener(){
     
            @Override
            public  void onClick(View v){
     
                checkAnswer(true);//调用checkAnswer(boolean)方法
            }
        });

        mFalseButton =(Button) findViewById(R.id.false_button);
        mFalseButton.setOnClickListener(new View.OnClickListener() {
     
            @Override
            public void onClick(View v){
     
                checkAnswer(false);//调用checkAnswer(boolean)方法
            }
        });
        mNextButton = (Button) findViewById(R.id.next_button);
        mNextButton.setOnClickListener(new View.OnClickListener() {
     
            @Override
            public void onClick(View view) {
     
                mCurrentIndex = (mCurrentIndex + 1) %  mQuestionBank.length;
                updateQuestion();

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

    }
//    增加checkAnswer(boolean)方法
    private void checkAnswer(boolean userPressedTrue) {
     
        boolean answerIsTrue = mQuestionBank[mCurrentIndex].isAnswerTrue();

        int messageResId = 0;

        if(userPressedTrue == answerIsTrue) {
     
            messageResId = R.string.correct_toast;
        }else{
     
            messageResId = R.string.incorrect_toast;
        }
        Toast.makeText(this,messageResId,Toast.LENGTH_SHORT).show();
    }

}

4. Question.java

先新建Question.java

package com.example.test3;

public class Question {
     
    private int mTextRestId;//变量mTextResId用来保存地理知识,而问题字符串的资源ID。资源ID总是int类型，所以这里设置它为int类型。
    private boolean mAnswerTrue;

    public Question(int textRestId, boolean answerTrue) {
     
        mTextRestId = textRestId;
        mAnswerTrue = answerTrue;
    }

    public int getTextRestId() {
     
        return mTextRestId;
    }

    public void setTextRestId(int textRestId) {
     
        mTextRestId = textRestId;
    }

    public boolean isAnswerTrue() {
     
        return mAnswerTrue;
    }

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

5. activity_main.xml

<?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>

    <Button
        android:id="@+id/next_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/next_button"
        android:drawableRight="@drawable/arrow_right"
        android:drawablePadding="4dp"/>
</LinearLayout>

6. strings.xml

<resources>
    <string name="app_name">test3</string>
    <string name="question_australia">Canberra is the capital of Australia.</string>
    <string name="question_oceans">The Pacific Ocean is larger than the Atlantic Ocean.</string>
    <string name="question_mideast">The Suez Canal connects the Red Sea and the Indian Ocean.</string>
    <string name="question_africa">The source of the Nile River is in Egypt.</string>
    <string name="question_americas">The Amazon River is the longest river in the Americas.</string>
    <string name="question_asia">Lake Baikal is the world\'s oldest and deepest freshwater lake.//为得到符号'，这里使用了转义字符。
    <string name="true_button">True</string>
    <string name="false_button">False</string>
    <string name="next_button">Next</string><!--    添加新按钮所需的字符串资源定义-->
    <string name="correct_toast">Correct!</string>
    <string name="incorrect_toast">Incorrect!</string>
</resources>

7. 效果