Question

public boolean isValidPin(String pin) {

type = false; 
Cursor c =db .rawQuery( "select * from"+ pinTable+" where Pin='" + pin+ "'", null); 
if (c.getCount() > 0) 
{ 
c.moveToFirst(); 
type = true; 
}
 c.close(); 
return type; 
}

我在android中的对话框上有一个按钮当我点击它强行停止... 这是logcat错误..

03-26 07:35:23.140: E/AndroidRuntime(16907): FATAL EXCEPTION: main
03-26 07:35:23.140: E/AndroidRuntime(16907): java.lang.NullPointerException
03-26 07:35:23.140: E/AndroidRuntime(16907):    at com.android.lnt_form.WayDataBase.isValidPin(WayDataBase.java:147)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at com.android.lnt_form.LoginActivity$3.onClick(LoginActivity.java:133)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at android.view.View.performClick(View.java:4202)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at android.view.View$PerformClick.run(View.java:17340)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at android.os.Handler.handleCallback(Handler.java:725)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at android.os.Handler.dispatchMessage(Handler.java:92)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at android.os.Looper.loop(Looper.java:137)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at android.app.ActivityThread.main(ActivityThread.java:5039)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at java.lang.reflect.Method.invokeNative(Native Method)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at java.lang.reflect.Method.invoke(Method.java:511)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-26 07:35:23.140: E/AndroidRuntime(16907):    at dalvik.system.NativeStart.main(Native Method)

请帮助。我该怎么纠正它？

Answer 1

在这里继续下去并不多，但我会尝试一下，并说你在尝试访问它之前没有初始化你的数据库。这将在该行上给出一个nullpointer。

android中按钮单击错误

1 个答案: