Java 我不知道';没有错误,但我的应用程序一直关闭
基于代码,我没有问题,但为什么我的应用程序在运行时一直关闭 我是java的初学者 我正在为我的论文做一个测验应用程序 ps我只复制youtube上的代码并编辑它 请帮助我打开我的应用程序 MainActivity.java javaJava 我不知道';没有错误,但我的应用程序一直关闭,java,android,arrays,runtime-error,Java,Android,Arrays,Runtime Error,基于代码,我没有问题,但为什么我的应用程序在运行时一直关闭 我是java的初学者 我正在为我的论文做一个测验应用程序 ps我只复制youtube上的代码并编辑它 请帮助我打开我的应用程序 MainActivity.java java package com.example.ltoexam; import androidx.appcompat.app.AppCompatActivity; import android.os.Bundle; import android.view.View; i
package com.example.ltoexam;
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 LtoQuiz extends AppCompatActivity {
private com.example.ltoexam.QuestionLibrary nQuestionLibrary = new com.example.ltoexam.QuestionLibrary();
private TextView nScoreView;
private TextView nQuestionView;
private Button nButtonChoice1;
private Button nButtonChoice2;
private Button nButtonChoice3;
private String nAnswer;
private int nScore = 0;
private int nQuestionNumber = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
nScoreView = (TextView) findViewById(R.id.score);
nQuestionView = (TextView) findViewById(R.id.question);
nButtonChoice1 = (Button) findViewById(R.id.choice1);
nButtonChoice2 = (Button) findViewById(R.id.choice2);
nButtonChoice3 = (Button) findViewById(R.id.choice3);
updateQuestion();
//Start of Button Listener for Button1
nButtonChoice1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//My logic for Button goes in here
if (nButtonChoice1.getText() == nAnswer){
nScore =nScore + 1;
updateScore(nScore);
updateQuestion();
//This line of code is optional
Toast.makeText(LtoQuiz.this, "correct", Toast.LENGTH_SHORT).show();
}else {
Toast.makeText(LtoQuiz.this, "wrong", Toast.LENGTH_SHORT).show();
updateQuestion();
}
}
});
//End of Button Listener for Button2
//Start of Button Listener for Button2
nButtonChoice2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//My logic for Button goes in here
if (nButtonChoice2.getText() == nAnswer){
nScore =nScore + 1;
updateScore(nScore);
updateQuestion();
//This line of code is optional
Toast.makeText(LtoQuiz.this, "correct", Toast.LENGTH_SHORT).show();
}else {
Toast.makeText(LtoQuiz.this, "wrong", Toast.LENGTH_SHORT).show();
updateQuestion();
}
}
});
//End of Button Listener for Button2
//Start of Button Listener for Button3
nButtonChoice3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//My logic for Button goes in here
if (nButtonChoice3.getText() == nAnswer){
nScore =nScore + 1;
updateScore(nScore);
updateQuestion();
//This line of code is optional
Toast.makeText(LtoQuiz.this, "correct", Toast.LENGTH_SHORT).show();
}else {
Toast.makeText(LtoQuiz.this, "wrong", Toast.LENGTH_SHORT).show();
updateQuestion();
}
}
});
//End of Button Listener for Button2
}
private void updateQuestion(){
nQuestionView.setText(nQuestionLibrary.getQuestion(nQuestionNumber));
nButtonChoice1.setText(nQuestionLibrary.getChoice1(nQuestionNumber));
nButtonChoice2.setText(nQuestionLibrary.getChoice2(nQuestionNumber));
nButtonChoice3.setText(nQuestionLibrary.getChoice3(nQuestionNumber));
nAnswer = nQuestionLibrary.getCorrectAnswer(nQuestionNumber);
nQuestionNumber++;
}
private void updateScore(int point){
nScoreView.setText("" + nScore);
}
}
QuestionLibrary.java
package com.example.ltoexam;
public class QuestionLibrary {
private String nQuestions [] = {
"1.The three colors of the traffic lights are:",
"2.Yellow triangular signs provide what kind of information",
"3.Which of the following traffic signs are blue?",
"4.Steady green light means",
"5.A flashing yellow light at a road crossing signifies",
"6.A solid white line on the right edge of the highway slopes in towards your left. This shows that",
"7.You are in a No-Passing zone when the center of the road is marked by"
};
private String nChoices [] [] = {
{"red, green and yellow", "red, green and blue", "yellow, green and blue"},
{"warning", "hospital across", "speed limit"},
{"regulatory signs", "information signs", "danger warning signs"},
{"you must yield to all pedestrians and other motorists using the intersection", "go, it is safe to do so", "proceed cautiously through the intersection before the light changes to red."},
{"Caution - slow down and proceed with caution", "Stop and stay until light stops flashing", "Wait for the green light"},
{"there is an intersection joint ahead", "the road will get narrower", "you are approaching a construction area"},
{"a broken yellow line","a broken white line","two solid yellow lines"}
};
private String nCorrectAnsers[] = {"red, green and yellow", "warning", "information signs", "go, it is safe to do so", "Caution - slow down and proceed with caution", "the road will get narrower", "two solid yellow lines"};
public String getQuestion(int a) {
String question = nQuestions[a];
return question;
}
public String getChoice1(int a) {
String choice0 = nChoices[a] [0];
return choice0;
}
public String getChoice2(int a) {
String choice1 = nChoices[a] [1];
return choice1;
}
public String getChoice3(int a) {
String choice2 = nChoices[a] [2];
return choice2;
}
public String getCorrectAnswer(int a) {
String answer = nCorrectAnsers[a];
return answer;
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingLeft="16dp"
android:paddingTop="16dp"
android:paddingRight="16dp"
android:paddingBottom="16dp"
tools:context=".LtoQuiz">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="8dp"
android:layout_marginBottom="40dp">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Score"
android:textSize="20sp"
android:layout_alignParentLeft="true"
android:id="@+id/score_text"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="20sp"
android:layout_alignParentRight="true"
android:text="0"
android:id="@+id/score"/>
</RelativeLayout>
<TextView
android:layout_width="match_parent"
android:layout_height="70dp"
android:text="Which thing is alive?"
android:textSize="20sp"
android:padding="8dp"
android:layout_marginBottom="40dp"
android:id="@+id/question"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="bird"
android:background="#0091EA"
android:textColor="#fff"
android:padding="8dp"
android:layout_marginBottom="24dp"
android:id="@+id/choice1"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="door"
android:background="#0091EA"
android:textColor="#fff"
android:padding="8dp"
android:layout_marginBottom="24dp"
android:id="@+id/choice2"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="rock "
android:background="#0091EA"
android:textColor="#fff"
android:padding="8dp"
android:layout_marginBottom="24dp"
android:id="@+id/choice3"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Quit"
android:background="#871C1C"
android:textColor="#fff"
android:padding="8dp"
android:layout_marginBottom="24dp"
android:id="@+id/quit"/>
</LinearLayout>
日志未完成
08 18:54:20.316 595-595/?V/LocSvc_HIDL_IzatSubscription:[wifiSupplicantStatusUpdate][682][HS]如果您检查了错误消息的这一部分,请注意:
: java.lang.ClassNotFoundException: Didn't find class"com.example.ltoexam.MainActivity"
你可以看到,android studio正在寻找MainActivity类。通过快速查看您提供的信息,没有MainActivity类。这是在运行应用程序时第一次调用的类,并且具有该活动的布局。(必须称为MainActivity.class)未找到类“com.example.ltoexam.MainActivity”您的清单编写是否正确?您也应该发布
“我没有错误”
,但是这个java.lang.RuntimeException:无法实例化活动组件信息{com.example.ltoexam/com.example.ltoexam.MainActivity}:java.lang.ClassNotFoundException:没有找到类“com.example.ltoexam.MainActivity”
讲述了另一个故事。请发布您的清单文件(AndroidManifest.xml)代码
: java.lang.ClassNotFoundException: Didn't find class"com.example.ltoexam.MainActivity"