我使用Android Studio制作了一个问题和答案应用程序，但它一直在崩溃。侧面没有显示错误（它标记为绿色），但在我第一次尝试提交答案后崩溃了。我发现它在onClick方法中抛出了一个空指针异常。我已经看了一下并尝试了我能找到的解决方案但到目前为止无法修复此错误。以下是崩溃页面中的代码。任何帮助将不胜感激。
package com.example.jeff.mygame;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
public class QuestionActivity extends Activity {
Intent intent;
TextView tv;
Button submitButton;
RadioGroup radioGroup;
RadioButton choice1, choice2, choice3, givenAnswer;
String answersText;
String questions[] = {"Which studio developed Elder Scrolls V: Skyrim?", "Who is the main character in the Mass Effect series?",
"Which indie games company developed the Walking Dead series?"};
String answers[] = {"Bethesda", "Commander Shepard", "TellTale Games"};
String choices[] = {"Bioware", "Bethesda", "Ubisoft", "Commander Shepard", "Garrus Vakarian", "Illusive Man", "Team Meat", "Way Forward", "TellTale Games"};
int flag = 0;
public static int results, correct, incorrect;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_question);
tv = (TextView)findViewById(R.id.tvQ1);
choice1 = (RadioButton)findViewById(R.id.rb1);
choice2 = (RadioButton)findViewById(R.id.rb2);
choice3 = (RadioButton)findViewById(R.id.rb3);
submitButton = (Button)findViewById(R.id.submit1);
tv.setText(questions[flag]);
choice1.setText(choices[0]);
choice2.setText(choices[1]);
choice3.setText(choices[2]);
submitButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
givenAnswer = (RadioButton)findViewById(radioGroup.getCheckedRadioButtonId());
answersText = givenAnswer.getText().toString();
if(answersText.equals(answers[flag])){
correct++;
}else{
incorrect++;
}flag++;
if(flag < questions.length){
tv.setText(questions[flag]);
choice1.setText(choices[flag*3]);
choice2.setText(choices[flag*3]);
choice3.setText(choices[flag*3]);
}else{
results = correct;
intent = new Intent(getApplicationContext(),FinishActivity.class);
startActivity(intent);
}
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_question, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
这是我最初忘记添加的logcat。
05-05 17:34:49.744 652-658/com.example.jeff.mygame I/dalvikvm﹕ threadid=3: reacting to signal 3
05-05 17:34:49.775 652-658/com.example.jeff.mygame I/dalvikvm﹕ Wrote stack traces to '/data/anr/traces.txt'
05-05 17:34:51.595 652-652/com.example.jeff.mygame I/Process﹕ Sending signal. PID: 652 SIG: 9
05-05 17:42:07.295 704-709/com.example.jeff.mygame I/dalvikvm﹕ threadid=3: reacting to signal 3
05-05 17:42:07.465 704-709/com.example.jeff.mygame I/dalvikvm﹕ Wrote stack traces to '/data/anr/traces.txt'
05-05 17:42:07.775 704-709/com.example.jeff.mygame I/dalvikvm﹕ threadid=3: reacting to signal 3
05-05 17:42:07.885 704-709/com.example.jeff.mygame I/dalvikvm﹕ Wrote stack traces to '/data/anr/traces.txt'
05-05 17:42:08.105 704-704/com.example.jeff.mygame D/gralloc_goldfish﹕ Emulator without GPU emulation detected.
05-05 17:42:11.465 704-704/com.example.jeff.mygame D/AndroidRuntime﹕ Shutting down VM
05-05 17:42:11.465 704-704/com.example.jeff.mygame W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
05-05 17:42:11.475 704-704/com.example.jeff.mygame E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.jeff.mygame.QuestionActivity$1.onClick(QuestionActivity.java:48)
at android.view.View.performClick(View.java:3511)
at android.view.View$PerformClick.run(View.java:14105)
at android.os.Handler.handleCallback(Handler.java:605)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4424)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
05-05 17:42:12.015 704-709/com.example.jeff.mygame I/dalvikvm﹕ threadid=3: reacting to signal 3
05-05 17:42:12.025 704-709/com.example.jeff.mygame I/dalvikvm﹕ Wrote stack traces to '/data/anr/traces.txt'
05-05 17:42:15.525 704-704/com.example.jeff.mygame I/Process﹕ Sending signal. PID: 704 SIG: 9
答案 0 :(得分：1)
您尚未初始化radioGroup。你需要做如下
radioGroup = (RadioGroup) findViewById(R.id.myRadioGroup);
radioGroup.setOnCheckedChangeListener(new OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
// find which radio button is selected
if(checkedId == R.id.rb1) {
// do action
}
}
});
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
int selectedId = radioGroup.getCheckedRadioButtonId();
// find which radioButton is checked by id
if(selectedId == R.id.rb1 ) {
// you have chosen so and so radio button
}
// similarly check other buttons
}
});