你能看看我的代码有什么问题吗? 我按下按钮时尝试创建对话框。 我没有看到错误,但是logcat在这一行中显示了java.lang.NullPointerException“agree.setOnClickListener(new OnClickListener(){”
package com.sociyo;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.pm.ActivityInfo;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.widget.Button;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT); //Lock Orientation
requestWindowFeature(Window.FEATURE_NO_TITLE); //Hide Action menu
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); //Load main activity
//viewPager default page
ViewPagerAdapter adapter = new ViewPagerAdapter();
ViewPager myPager = (ViewPager) findViewById(R.id.pager);
myPager.setAdapter(adapter);
myPager.setCurrentItem(0);
//textView clickable
Button agree = (Button)findViewById(R.id.btnTerms);
agree.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
AlertDialog.Builder tpDialog = new AlertDialog.Builder(null);
tpDialog.setTitle("Terms and Policy");
tpDialog.setMessage(R.string.action_settings)
.setCancelable(false)
.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
MainActivity.this.finish();
}
});
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
这是完整的日志猫:
E/AndroidRuntime(13076): FATAL EXCEPTION: main
E/AndroidRuntime(13076): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sociyo/com.sociyo.MainActivity}: java.lang.NullPointerException
E/AndroidRuntime(13076): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2070)
E/AndroidRuntime(13076): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2095)
E/AndroidRuntime(13076): at android.app.ActivityThread.access$600(ActivityThread.java:137)
E/AndroidRuntime(13076): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1206)
E/AndroidRuntime(13076): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(13076): at android.os.Looper.loop(Looper.java:213)
E/AndroidRuntime(13076): at android.app.ActivityThread.main(ActivityThread.java:4793)
E/AndroidRuntime(13076): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(13076): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(13076): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
E/AndroidRuntime(13076): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
E/AndroidRuntime(13076): at dalvik.system.NativeStart.main(Native Method)
**E/AndroidRuntime(13076): Caused by: java.lang.NullPointerException**
E/AndroidRuntime(13076): at com.sociyo.MainActivity.onCreate(MainActivity.java:34)
E/AndroidRuntime(13076): at android.app.Activity.performCreate(Activity.java:5008)
E/AndroidRuntime(13076): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
E/AndroidRuntime(13076): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2034)
E/AndroidRuntime(13076): ... 11 more
My activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:background="@drawable/background"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true" >
</android.support.v4.view.ViewPager>
</RelativeLayout>
我的activity_register.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:background="@android:color/transparent"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical" >
<TextView
android:id="@+id/tvRegisterTitle"
style="@style/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="@string/register_text"
android:textAppearance="?android:attr/textAppearanceLarge" />
<EditText
android:id="@+id/etNameReg"
style="@style/textfield"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/spMlmList"
android:layout_centerHorizontal="true"
android:layout_marginTop="15dp"
android:ems="10"
android:hint="@string/name_hint"
android:inputType="textPersonName" >
<requestFocus />
</EditText>
<EditText
android:id="@+id/etEmailReg"
style="@style/textfield"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/etNameReg"
android:layout_centerHorizontal="true"
android:layout_marginTop="15dp"
android:ems="10"
android:hint="@string/email_hint"
android:inputType="textEmailAddress" />
<EditText
android:id="@+id/etPasswordReg"
style="@style/textfield"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/etEmailReg"
android:layout_below="@+id/etEmailReg"
android:layout_centerVertical="true"
android:layout_marginTop="15dp"
android:ems="10"
android:hint="@string/password_hint"
android:inputType="textPassword" />
<Spinner
android:id="@+id/spMlmList"
style="@style/textfield"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/tvRegisterTitle"
android:layout_below="@+id/tvRegisterTitle"
android:layout_marginTop="15dp"
android:entries="@array/mlm_list" />
<Button
android:id="@+id/btnRegister"
style="@style/buttonBlue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/etPasswordReg"
android:layout_below="@+id/chkAgree"
android:layout_marginTop="15dp"
android:text="@string/register_text" />
<CheckBox
android:id="@+id/chkAgree"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/etPasswordReg"
android:text="@string/agree_text"
android:layout_marginTop="15dp"
style="@style/checkbox"/>
<Button
android:id="@+id/btnTerms"
android:background="@android:color/transparent"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/chkAgree"
android:layout_alignBottom="@+id/chkAgree"
android:layout_toRightOf="@+id/tvRegisterTitle"
android:layout_marginLeft="10dp"
android:text="@string/terms_policy"
style="@style/smallLink"/>
</RelativeLayout>
答案 0 :(得分:3)
是的,此时按钮不存在。
您的R.id.btnTermsR.id.btnTerms在activity_register.xml中定义,但该布局永远不会膨胀。或者在那时无法访问:)
它是具有问题的按钮,而不是OnClickListener。监听器中的nullpointer将在您单击按钮时出现,而不是在连接时出现。
答案 1 :(得分:1)
// Before Replace
AlertDialog.Builder tpDialog = new AlertDialog.Builder(null);
// After Replace
AlertDialog.Builder tpDialog = new AlertDialog.Builder(MainActivity.this);
答案 2 :(得分:0)
AlertDialog.Builder tpDialog = new AlertDialog.Builder(null);
change this line too
AlertDialog.Builder tpDialog = new AlertDialog.Builder(MainActivity.this);