无法实例化活动组件信息{…}java.lang.NullPointerException
我是java语言的初学者,我搜索过其他解决方案,但没有人为我工作,该应用程序甚至不能专门化,logcat说:无法实例化活动组件信息{…}java.lang.NullPointerException,java,android,nullpointerexception,Java,Android,Nullpointerexception,我是java语言的初学者,我搜索过其他解决方案,但没有人为我工作,该应用程序甚至不能专门化,logcat说: 03-13 15:08:22.544: D/AndroidRuntime(7595): Shutting down VM 03-13 15:08:22.544: W/dalvikvm(7595): threadid=1: thread exiting with uncaught exception (group=0x416d1d40) 03-13 15:08:22.549: E/Andr
03-13 15:08:22.544: D/AndroidRuntime(7595): Shutting down VM
03-13 15:08:22.544: W/dalvikvm(7595): threadid=1: thread exiting with uncaught exception (group=0x416d1d40)
03-13 15:08:22.549: E/AndroidRuntime(7595): FATAL EXCEPTION: main
03-13 15:08:22.549: E/AndroidRuntime(7595): Process: com.germaka.clientes, PID: 7595
03-13 15:08:22.549: E/AndroidRuntime(7595): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.germaka.clientes/com.germaka.clientes.MainActivity}: java.lang.NullPointerException
03-13 15:08:22.549: E/AndroidRuntime(7595): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2135)
03-13 15:08:22.549: E/AndroidRuntime(7595): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2269)
03-13 15:08:22.549: E/AndroidRuntime(7595): at android.app.ActivityThread.access$800(ActivityThread.java:139)
03-13 15:08:22.549: E/AndroidRuntime(7595): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
03-13 15:08:22.549: E/AndroidRuntime(7595): at android.os.Handler.dispatchMessage(Handler.java:102)
03-13 15:08:22.549: E/AndroidRuntime(7595): at android.os.Looper.loop(Looper.java:136)
03-13 15:08:22.549: E/AndroidRuntime(7595): at android.app.ActivityThread.main(ActivityThread.java:5102)
03-13 15:08:22.549: E/AndroidRuntime(7595): at java.lang.reflect.Method.invokeNative(Native Method)
03-13 15:08:22.549: E/AndroidRuntime(7595): at java.lang.reflect.Method.invoke(Method.java:515)
03-13 15:08:22.549: E/AndroidRuntime(7595): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
03-13 15:08:22.549: E/AndroidRuntime(7595): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
03-13 15:08:22.549: E/AndroidRuntime(7595): at dalvik.system.NativeStart.main(Native Method)
03-13 15:08:22.549: E/AndroidRuntime(7595): Caused by: java.lang.NullPointerException
03-13 15:08:22.549: E/AndroidRuntime(7595): at android.app.Activity.findViewById(Activity.java:1892)
03-13 15:08:22.549: E/AndroidRuntime(7595): at com.germaka.clientes.MainActivity.<init>(MainActivity.java:17)
03-13 15:08:22.549: E/AndroidRuntime(7595): at java.lang.Class.newInstanceImpl(Native Method)
03-13 15:08:22.549: E/AndroidRuntime(7595): at java.lang.Class.newInstance(Class.java:1208)
03-13 15:08:22.549: E/AndroidRuntime(7595): at android.app.Instrumentation.newActivity(Instrumentation.java:1084)
03-13 15:08:22.549: E/AndroidRuntime(7595): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2126)
03-13 15:08:22.549: E/AndroidRuntime(7595): ... 11 more
在其他解决方案中,他们说清单在这个错误中很重要,所以这里是:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.germaka.clientes"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.germaka.clientes.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".SQLiteVista"></activity>
</application>
</manifest>
提前感谢更改为
EditText nombre;
EditText direccion;
Button insertar;
Button ver ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); // must be first
nombre = (EditText) findViewById(R.id.editText1); // then initialize views
direccion = (EditText) findViewById(R.id.editText2);
insertar = (Button) findViewById(R.id.R.id.Insertar);
ver = (Button) findViewById(R.id.Ver);
在
onCreate
中将布局设置为活动后,您需要进行初始化,因为findViewById
查找具有当前扩展布局中提到的id的视图。您在创建活动
布局之前初始化了视图,这就是发生NullPointerException
的原因。现在,在onCreate()
方法中初始化它们……您的问题将得到解决
EditText nombre;
EditText direccion;
Button insertar;
Button ver;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
nombre = (EditText) findViewById(R.id.editText1);
direccion = (EditText) findViewById(R.id.editText2);
insertar = (Button) findViewById(R.id.Insertar);
ver = (Button) findViewById(R.id.Ver);
insertar.setOnClickListener(this);
ver.setOnClickListener(this);
}
它仍然不工作,我的日志更改为这个抱歉你评论first@GermanKatz你为什么不接受我的回答。只是身份证的打字错误。但答案是正确的,解释也是正确的。很高兴听到这一点……那么,请接受答案。:)@GermanKatz…你已经接受了他的答案…但首先,他的答案是不正确的…他的答案是由
R.id.In
组成的,这是不正确的…他当前的答案也是不正确的原因,他的答案是由R.id.R.id.Insertar
组成的,这也是不正确的。正确的id是R.id.Insertar
。但是,我的答案从一开始到现在都是正确的。现在,你决定接受哪个答案。
EditText nombre;
EditText direccion;
Button insertar;
Button ver;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
nombre = (EditText) findViewById(R.id.editText1);
direccion = (EditText) findViewById(R.id.editText2);
insertar = (Button) findViewById(R.id.Insertar);
ver = (Button) findViewById(R.id.Ver);
insertar.setOnClickListener(this);
ver.setOnClickListener(this);
}