Android setContentView問題

我的第一個應用程序顯示了承諾，但現在「意外停止」。我已經將它降低到最低限度以顯示失敗，這在執行SetContentView時會發生。Android setContentView問題

問題：

一）有一個明顯的錯誤嗎？ b）我應該如何去調試這個故障？

謝謝！

package com.xxx.try1; 

import android.app.Activity; 
// sundry imports 

public class Chrisgeturltry1Activity extends Activity { 
private TextView lblDATE = new TextView(this); 
private ViewGroup mainPanel; 
// 
public void onCreate(Bundle istate) { 
    super.onCreate(istate); 

    // create the panel to enclose everything 
    mainPanel = makeForm(); 
    // show the panel on the screen 
    setContentView(mainPanel); 
} 
//------------------------------------------------------------------------------------------------------------ 
// create the form and establish onClick method for the button 
private ViewGroup makeForm() { 

    LinearLayout panel = new LinearLayout(this); 
    panel.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT)); 
    panel.setOrientation(LinearLayout.VERTICAL); 
    panel.setBackgroundColor(-0xDD99DD); 

    lblDATE.setTextSize(TypedValue.COMPLEX_UNIT_SP, 16f); 
    lblDATE.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT)); 
    lblDATE.setBackgroundColor(Color.WHITE); 
    lblDATE.setTextColor(Color.BLACK); 
    lblDATE.setTypeface(Typeface.MONOSPACE,2); 
    lblDATE.setText("date"); 
    return panel; 
}

}

錯誤日誌： OK，這裏是錯誤的logcat的：


09-07 16:02:59.037: ERROR/AndroidRuntime(492): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.chrisdev.geturltry1/com.chrisdev.geturltry1.Chrisgeturltry1Activity}: java.lang.NullPointerException 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1544) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1638) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.app.ActivityThread.access$1500(ActivityThread.java:117) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:928) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.os.Handler.dispatchMessage(Handler.java:99) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.os.Looper.loop(Looper.java:123) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.app.ActivityThread.main(ActivityThread.java:3647) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at java.lang.reflect.Method.invokeNative(Native Method) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at java.lang.reflect.Method.invoke(Method.java:507) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at dalvik.system.NativeStart.main(Native Method) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492): Caused by: java.lang.NullPointerException 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.content.ContextWrapper.getResources(ContextWrapper.java:80) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.view.View.(View.java:1874) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.view.View.(View.java:1921) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.widget.TextView.(TextView.java:344) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.widget.TextView.(TextView.java:337) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.widget.TextView.(TextView.java:332) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at com.chrisdev.geturltry1.Chrisgeturltry1Activity.(Chrisgeturltry1Activity.java:28) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at java.lang.Class.newInstanceImpl(Native Method) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at java.lang.Class.newInstance(Class.java:1409) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.app.Instrumentation.newActivity(Instrumentation.java:1021) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1536) 
09-07 16:02:59.037: ERROR/AndroidRuntime(492):  ... 11 more

來源

2011-09-07 SirHowy

您應該提供應用程序錯誤的堆棧跟蹤。或者沒有錯誤信息？ –

打印堆棧跟蹤。錯誤 – confucius

<無法實例化活動ComonemtInfo ....> – SirHowy

當查看這樣的LogCat錯誤時，我開始尋找任何直接引用我的代碼的行。在這種情況下，這就是com.chrisdev.geturltry1.Chrisgeturltry1Activity.(Chrisgeturltry1Activity.java:28)

您可以雙擊該行直接跳到代碼中的位置（假設您正在使用Eclipse）並從那裏進行調試。

編輯：斯蒂芬可能是正確的 - 嘗試在onCreate或您的makeForm方法中實例化lblDATE，而不是您聲明它的地方，看看是否有幫助。

來源

2011-09-07 16:35:58

問題是lblDATE爲空，據我所看到的。在onCreate中實例化它。

來源

2011-09-07 16:34:21

Android setContentView問題

回答

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