Question

这是主要的java文件，我试图使用settext方法，但每次使用它都会让我强行关闭

  public class SecondActivity extends Activity {

    TextView myAwesomeTextView;

         @Override
      public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

       myAwesomeTextView = (TextView) findViewById(R.id.myAwesomeTextView);
       myAwesomeTextView.setText("My Awesome Text");


    }
   }

XML

<LinearLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical"
     android:layout_width="match_parent"
     android:layout_height="match_parent">

<TextView
   android:id="@+id/myAwesomeTextView"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:text="s"
   android:textSize="20sp"
   android:editable="true"/>
</LinearLayout>

这是我的第一个应用程序，所以我不太了解android我搜索了很多，但我coudnt修复它，因此我问最好的group.thankyou

logcat的

12-13 12:21:37.946  29196-29196/eu.itcsolutions.android.tutorial D/AndroidRuntime﹕ Shutting down VM
12-13 12:21:37.947  29196-29196/eu.itcsolutions.android.tutorial E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: eu.itcsolutions.android.tutorial, PID: 29196
    java.lang.RuntimeException: Unable to start activity ComponentInfo{eu.itcsolutions.android.tutorial/eu.itcsolutions.android.tutorial.SecondActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
            at eu.itcsolutions.android.tutorial.SecondActivity.onCreate(SecondActivity.java:47)
            at android.app.Activity.performCreate(Activity.java:5933)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
12-13 12:21:39.658  29196-29196/eu.itcsolutions.android.tutorial I/Process﹕ Sending signal. PID: 29196 SIG: 9

Answer 1

您需要使用setContentView(R.layout.second)代替setContentView(R.layout.main)。

public class SecondActivity extends Activity {

    TextView myAwesomeTextView;

         @Override
      public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.second);

       myAwesomeTextView = (TextView) findViewById(R.id.myAwesomeTextView);
       myAwesomeTextView.setText("My Awesome Text");


    }
   }

尝试在textview中显示文本时，settext force关闭

1 个答案: