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按钮相关问题:尝试在空对象引用上调用虚方法

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我在Android中遇到了这个问题 . 01-30 20:32:57.415 24227-24227 / edu.gatech.seclass.vcipher E / AndroidRuntime:FATAL EXCEPTION:main进程:edu.gatech.seclass.vcipher,PID:24227 java.lang.RuntimeException:无法启动活动ComponentInfo {edu.gatech.seclass.vcipher / edu.gatech.seclass.vcipher.VCipherActivity}:java.lang.NullPointerException:尝试调用虚方法'void android.widget.Button.setOnClickListener(android.view.View $ OnClickListener) '在android.app.ActivityThread.perleLaunchActivity(ActivityThread.java:2946)上的一个空对象引用,位于android.app.ActivityThread.-wrap11的android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3046)(未知来源:0 )在android.app.A活动上运行android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1688)android.os.Looper.loop(Handler.java:105)android.os.Looper.loop(Looper.java:164) .app.ActivityThread.main(ActivityThread.java:6809)位于com.android.internal.os.Zygote的java.lang.reflect.Method.invoke(Native Method)$ MethodAndArgs Caller.run(Zygote.java:240)at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)引起:java.lang.NullPointerException:尝试调用虚方法'void android.widget.Button .setOnClickListener(android.view.View $ OnClickListener)'在edu.gatech.seclass.vcipher.VCipherActivity.onCreate(VCipherActivity.java:48)的空对象引用上,位于android.app.Activity.performCreate(Activity.java:6998) )在android.app.Anstrumentation.callActivityOnCreate(Instrumentation.java:1230)的android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2899)android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3046)android.app .ActivityThread.-wrap11(未知来源:0)在Android.app.Looper的android.app.Handler.dispatchMessage(Handler.java:105)上的android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1688) . 在com.andro的java.lang.reflect.Method.invoke(Native Method)的android.app.ActivityThread.main(ActivityThread.java:6809)上循环(Looper.java:164) id.internal.os.Zygote $ MethodAndArgsCaller.run(Zygote.java:240)at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)------------- ---------------------------------好像我有一些与我的按钮有关的问题 . 但我的按钮引用不是null,但我仍然遇到此问题 .


Please help me in resolving this.I am stucked in my android development due to this issue. Not able to resolve it.Help is very much appreciated.

Thanks

1 回答

  • 1

    因为你在xml上的id是android:id = "@+id/button" not btn,你就会在那里有空 .
    你必须改变

    final android.widget.Button button1 = (Button) findViewById(R.id.btn);
    

    final android.widget.Button button1 = (Button) findViewById(R.id.button);
    

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