中国网站建设世界排名,心得体会万能模板,用wordpress 部署,湖北网站设计制作多少钱这个问题在这里已有答案#xff1a;我试图写一个应用程序#xff0c;如果在给定的URL中有一个文件#xff0c;将字符串放在textview中#xff0c;这是代码和崩溃信息#xff0c;可能是什么错误#xff1f;public class MainActivity extends AppCompatActivity {String u…这个问题在这里已有答案我试图写一个应用程序如果在给定的URL中有一个文件将字符串放在textview中这是代码和崩溃信息可能是什么错误public class MainActivity extends AppCompatActivity {String url https://images.pexels.com/photos/617278/pexels-photo-617278.jpeg?cssrgbdladorable-animal-blur-617278.jpgfmjpg;TextView textView;Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);textView.findViewById(R.id.textView);try {HttpURLConnection.setFollowRedirects(false);HttpURLConnection connection (HttpURLConnection) new URL(url).openConnection();connection.setRequestMethod(HEAD);connection.connect();if(connection.getResponseCode() HttpURLConnection.HTTP_OK){textView.setText(File Exists!!);}} catch (IOException e) {e.printStackTrace();}}}---------崩溃开始E / AndroidRuntimeFATAL EXCEPTIONmain进程com.example.android.archivoexistePID6160 java.lang.RuntimeException无法启动活动ComponentInfo {com.example . android.archivoexiste / com.example.android.archivoexiste.MainActivity}java.lang.NullPointerException尝试在android上的空对象引用上调用虚拟方法android.view.View android.widget.TextView.findViewById(int) Android.app.ActivityThread $中android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)的android.app.ActivityThread.-wrap11(未知来源0)的.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817) H.handleMessage(ActivityThread.java:1593)位于android.app.AooT.Thread.main的android.os.Handler.dispatchMessage(Handler.java:105)android.os.Looper.loop(Looper.java:164)(ActivityThread) .java6541)在java.lang.reflect.Method.invoke(Native Method)的com.android.internal.os.Zygote $ MethodAndArgsCaller.run(Zygote.java:240)at at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)引起java.lang.NullPointerException尝试调用虚拟方法android.view.View android.widget.TextView.findViewById(int)on位于android.app.Instrumentation.callActivityOnCreate(Instrumentation.java)的android.app.Activity.performCreate(Activity.java:6975)的com.example.android.archivoexiste.MainActivity.onCreate(MainActivity.java:23)中的空对象引用1213)在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)的android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)在android.app.ActivityThread.-wrap11(未知来源0)在android .app.ActivityThread $ H.handleMessage(ActivityThread.java:1593)位于android.app的android.os.Handler.dispatchMessage(Handler.java:105)android.os.Looper.loop(Looper.java:164) . ActivityThread.main(ActivityThread.java:6541)at java.lang.reflect.Method.invoke(Native Method)at com.android.internal.os.Zygote $ MethodAndArgsCaller.run(Zygot) e.java:240)在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)应用程序终止 .
