TextView 不显示文本
TextView doesn't show the text
抱歉这么长的锅,但我需要帮助。我是 Android World 的新手,正在阅读 Chris Stewart(The Big Nerd Ranch)的书 "Android Development"。一切顺利,但现在我被卡住了。当我 运行 我的应用程序时,它因这行代码
而崩溃
String text = Integer.toString(question);
照着书,给我看问题的正文。我也将代码更改为此,但它显示 0.
String text = Integer.toString(Integer.toString(question));
任何解决方案。提前致谢。
这是我的完整代码。
QuizActivity.java
package com.example.subrose.geoquiz;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
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 TextView mQuestionTextView;
private Question[] mQuestionBank = new Question[]{
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_quiz);
mQuestionTextView = (TextView)findViewById(R.id.question_text_view);
int question = mQuestionBank[mCurrentIndex].getTextResId();
mQuestionTextView.setText(question);
mTrueButton = (Button)findViewById(R.id.true_button);
mTrueButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(QuizActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT).show();
}
});
mFalseButton = (Button)findViewById(R.id.false_button);
mFalseButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(QuizActivity.this, R.string.incorrect_toast, Toast.LENGTH_SHORT).show();
}
});
}
}
Question.java
public class Question {
private int mTextResId;
private boolean mAnswerTrue;
public Question(int mTextResId, boolean mAnswerTrue)
{
mTextResId = mTextResId;
mAnswerTrue = mAnswerTrue;
}
public int getTextResId() {
return mTextResId;
}
public void setTextResId(int textResId) {
mTextResId = textResId;
}
public boolean isAnswerTrue() {
return mAnswerTrue;
}
public void setAnswerTrue(boolean answerTrue) {
mAnswerTrue = answerTrue;
}
}
Strings.xml
<resources>
<string name="app_name">GeoQuiz</string>
<string name="true_button">True</string>
<string name="false_button">False</string>
<string name="next_button">Next</string>
<string name="correct_toast">Correct!</string>
<string name="incorrect_toast">Incorrect!</string>
<string name="action_settings">Settings</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.</string>
</resources>
activity_quiz.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"/>
</LinearLayout>
您不能在 settext 中设置整数,因此更改代码
mQuestionTextView.setText(question);
替换为
mQuestionTextView.setText(String.valueOf(question));
你为什么不检查使用:
mQuestionTextView.setText(getString(mQuestionBank[mCurrentIndex].getTextResId()));
无论如何,我在你的代码中没有看到任何错误来设置视图中的文本。
int question = mQuestionBank[mCurrentIndex].getTextResId();
mQuestionTextView.setText(question);
要在 TextView 中设置整数,您有以下可能性:
替换为:
mQuestionTextView.setText(String.format(Locale.US, "%d", question));
或
mQuestionTextView.setText(question+"");
或
mQuestionTextView.setText(String.valueOf(question));
构造函数中的主要问题。更改如下。
public Question(int mTextResId, boolean mAnswerTrue)
{
this.mTextResId = mTextResId;
this.mAnswerTrue = mAnswerTrue;
}
您应该在数据隐藏中使用 this
。当前值未分配给实例变量,因为您只使用了本地变量。这就是他们返回默认值的原因。按照上面的方法做。
除此之外 setText()
有几个变体,如果您使用的是资源 ID,您可以直接使用 setText(int id)
。阅读 setText varients 。
抱歉这么长的锅,但我需要帮助。我是 Android World 的新手,正在阅读 Chris Stewart(The Big Nerd Ranch)的书 "Android Development"。一切顺利,但现在我被卡住了。当我 运行 我的应用程序时,它因这行代码
而崩溃String text = Integer.toString(question);
照着书,给我看问题的正文。我也将代码更改为此,但它显示 0.
String text = Integer.toString(Integer.toString(question));
任何解决方案。提前致谢。 这是我的完整代码。
QuizActivity.java
package com.example.subrose.geoquiz;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
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 TextView mQuestionTextView;
private Question[] mQuestionBank = new Question[]{
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_quiz);
mQuestionTextView = (TextView)findViewById(R.id.question_text_view);
int question = mQuestionBank[mCurrentIndex].getTextResId();
mQuestionTextView.setText(question);
mTrueButton = (Button)findViewById(R.id.true_button);
mTrueButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(QuizActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT).show();
}
});
mFalseButton = (Button)findViewById(R.id.false_button);
mFalseButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(QuizActivity.this, R.string.incorrect_toast, Toast.LENGTH_SHORT).show();
}
});
}
}
Question.java
public class Question {
private int mTextResId;
private boolean mAnswerTrue;
public Question(int mTextResId, boolean mAnswerTrue)
{
mTextResId = mTextResId;
mAnswerTrue = mAnswerTrue;
}
public int getTextResId() {
return mTextResId;
}
public void setTextResId(int textResId) {
mTextResId = textResId;
}
public boolean isAnswerTrue() {
return mAnswerTrue;
}
public void setAnswerTrue(boolean answerTrue) {
mAnswerTrue = answerTrue;
}
}
Strings.xml
<resources>
<string name="app_name">GeoQuiz</string>
<string name="true_button">True</string>
<string name="false_button">False</string>
<string name="next_button">Next</string>
<string name="correct_toast">Correct!</string>
<string name="incorrect_toast">Incorrect!</string>
<string name="action_settings">Settings</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.</string>
</resources>
activity_quiz.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"/>
</LinearLayout>
您不能在 settext 中设置整数,因此更改代码
mQuestionTextView.setText(question);
替换为
mQuestionTextView.setText(String.valueOf(question));
你为什么不检查使用:
mQuestionTextView.setText(getString(mQuestionBank[mCurrentIndex].getTextResId()));
无论如何,我在你的代码中没有看到任何错误来设置视图中的文本。
int question = mQuestionBank[mCurrentIndex].getTextResId();
mQuestionTextView.setText(question);
要在 TextView 中设置整数,您有以下可能性:
替换为:
mQuestionTextView.setText(String.format(Locale.US, "%d", question));
或
mQuestionTextView.setText(question+"");
或
mQuestionTextView.setText(String.valueOf(question));
构造函数中的主要问题。更改如下。
public Question(int mTextResId, boolean mAnswerTrue)
{
this.mTextResId = mTextResId;
this.mAnswerTrue = mAnswerTrue;
}
您应该在数据隐藏中使用 this
。当前值未分配给实例变量,因为您只使用了本地变量。这就是他们返回默认值的原因。按照上面的方法做。
除此之外 setText()
有几个变体,如果您使用的是资源 ID,您可以直接使用 setText(int id)
。阅读 setText varients 。