尝试运行应用程序时出现错误。
我希望有人能指出我正确的方向
这是我的问题开始的地方（第73行）：
USER_ID_TMP = userIdtext2.getText().toString();
较长的代码段：
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.tab1);
Log.i("tabs", "CurrentTab is: 1");
DB_NAME_AND_PATH = Tab1.this.getDatabasePath(DB_NAME);
Log.d("Haze", "DB_NAME_AND_PATH: "+DB_NAME_AND_PATH);
listView = (ListView) findViewById(R.id.listViewer);
Button copyDbButton = (Button)findViewById(R.id.copydbbutton);
Button readDbButton = (Button)findViewById(R.id.readdbbutton);
final EditText userIdtext= (EditText) findViewById(R.id.userIDtextBox);
EditText userIdtext2= (EditText) findViewById(R.id.userIDtextBox);
if(fileFound){
Log.d("Haze", "Filefound...........");
readDbButton.setEnabled(false);
}else{
Log.d("Haze", "FileNotfound...........");
fileFound = checkFileOnCreate(DB_NAME_AND_PATH);
readDbButton.setEnabled(true);
}
USER_ID_TMP = userIdtext2.getText().toString();
Log.d("Haze", "USER_ID_TMP: "+USER_ID_TMP);
USER_ID = USER_ID_TMP.toUpperCase();
final TextWatcher watcher= new TextWatcher() {
public void afterTextChanged(Editable s) {
if (userIdtext.getText().toString().equals("")) {
userIdtext.setBackgroundColor(getResources().getColor(android.R.color.white));
userIdtext.setTextColor(getResources().getColor(android.R.color.black));
}
错误信息：
05-13 03:43:08.778 2079-2079/com.androidexample.tabbar D/Haze﹕ FileNotfound...........
05-13 03:43:08.800 2079-2079/com.androidexample.tabbar D/AndroidRuntime﹕ Shutting down VM
05-13 03:43:08.800 2079-2079/com.androidexample.tabbar W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x409961f8)
05-13 03:43:08.828 2079-2079/com.androidexample.tabbar E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.androidexample.tabbar/com.androidexample.tabbar.TabBar}: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.androidexample.tabbar/com.androidexample.tabbar.Tab1}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
at android.app.ActivityThread.access$600(ActivityThread.java:122)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4340)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.androidexample.tabbar/com.androidexample.tabbar.Tab1}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
at android.app.ActivityThread.startActivityNow(ActivityThread.java:1796)
at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:135)
at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:347)
at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:682)
at android.widget.TabHost.setCurrentTab(TabHost.java:346)
at android.widget.TabHost.addTab(TabHost.java:236)
at com.androidexample.tabbar.TabBar.onCreate(TabBar.java:43)
at android.app.Activity.performCreate(Activity.java:4465)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
at android.app.ActivityThread.access$600(ActivityThread.java:122)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4340)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.androidexample.tabbar.Tab1.onCreate(Tab1.java:73)
at android.app.Activity.performCreate(Activity.java:4465)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
at android.app.ActivityThread.startActivityNow(ActivityThread.java:1796)
at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:135)
at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:347)
at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:682)
at android.widget.TabHost.setCurrentTab(TabHost.java:346)
at android.widget.TabHost.addTab(TabHost.java:236)
at com.androidexample.tabbar.TabBar.onCreate(TabBar.java:43)
at android.app.Activity.performCreate(Activity.java:4465)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
at android.app.ActivityThread.access$600(ActivityThread.java:122)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4340)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
最佳答案
您已使用tab1布局通过以下方式设置视图
setContentView（R.layout.tab1）;
然后在此行中使用id userIDtextBox初始化userIdtext2
EditText userIdtext2 =（EditText）findViewById（R.id.userIDtextBox）;
然后，通过以下代码获取userIdtext2的值
USER_ID_TMP = userIdtext2.getText（）。toString（）;
所以检查id是否为R.id.userIDtextBox在布局R.layout.tab1中是否可用？