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應用程序拋出NullException錯誤當前我的應用程序正在拉取數據庫信息並填充TabView中的列表視圖，但應用程序強制關閉後才能運行。當Initializng變量
當我初始化我的變量時，問題似乎在於。
下面是對的onCreate類和intializeVariables方法，其中的logcat顯示錯誤：
protected void onCreate(Bundle savedInstanceState) {
// Set activity to full screen!!
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
th = (TabHost) findViewById(R.id.tabhost);
th.setup();
TabSpec specs = th.newTabSpec("tag1");
// one tab
specs.setContent(R.id.tab1);
// what appears on actual tab
specs.setIndicator("Tools");
th.addTab(specs);
specs = th.newTabSpec("tag2");
// one tab
specs.setContent(R.id.tab2);
// what appears on actual tab
specs.setIndicator("Calorie Calculator");
th.addTab(specs);
specs = th.newTabSpec("tag3");
// one tab
specs.setContent(R.id.tab3);
// what appears on actual tab
specs.setIndicator("Your Stats!");
th.addTab(specs);
initializeVariables();
statListView = getListView();
statListView.setOnItemClickListener(statViewListener);
// map each name to a TextView
String[] from = new String[] { "name" };
int[] to = new int[] { R.id.tvStatistics };
statAdapter = new SimpleCursorAdapter(MainActivity.this,
R.layout.stat_list, null, from, to);
setListAdapter(statAdapter); // set adapter
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
this, R.array.spinActMultArray,
android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinActMult.setAdapter(adapter);
spinActMult.setOnItemSelectedListener(new spinActMultFunction());
}
private void initializeVariables() {
spinActMult = (Spinner) findViewById(R.id.spinActivityMultipler);
activityMultiplier = (TextView) findViewById(R.id.tvActMult);
maintCalories = (TextView) findViewById(R.id.tvMaintLevel);
calcCalories = (Button) findViewById(R.id.btnCalcCalories);
goalPicker = (RadioGroup) findViewById(R.id.rgGoalPicker);
calorieResult = (TextView) findViewById(R.id.tvCalResults);
lbmResult = (TextView) findViewById(R.id.tvLBMResult);
bmrResult = (TextView) findViewById(R.id.tvBMRResult);
etWeight = (EditText) findViewById(R.id.etWInput);
weightInt = etWeight.getText().toString();
etBodyfat = (EditText) findViewById(R.id.etBFInput);
bodyfatInt = etBodyfat.getText().toString();
goalPicker.setOnCheckedChangeListener(this);
calcCalories.setOnClickListener(this);
StopwatchActivity = (Button) findViewById(R.id.btnStopwatchActivity);
mapARun = (Button) findViewById(R.id.btnMapARun);
weightConverter = (Button) findViewById(R.id.btnWeightConverter);
mapARun.setOnClickListener(this);
weightConverter.setOnClickListener(this);
StopwatchActivity.setOnClickListener(this);
updateDB.setOnClickListener(this);
viewDB.setOnClickListener(this);
}
和logcat的：
05-10 03:41:52.687: E/AndroidRuntime(5974): FATAL EXCEPTION: main
05-10 03:41:52.687: E/AndroidRuntime(5974): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.uhi.fatfighter/com.uhi.fatfighter.MainActivity}: java.lang.NullPointerException
05-10 03:41:52.687: E/AndroidRuntime(5974): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2185)
05-10 03:41:52.687: E/AndroidRuntime(5974): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2210)
05-10 03:41:52.687: E/AndroidRuntime(5974): at android.app.ActivityThread.access$600(ActivityThread.java:142)
05-10 03:41:52.687: E/AndroidRuntime(5974): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1208)
05-10 03:41:52.687: E/AndroidRuntime(5974): at android.os.Handler.dispatchMessage(Handler.java:99)
05-10 03:41:52.687: E/AndroidRuntime(5974): at android.os.Looper.loop(Looper.java:137)
05-10 03:41:52.687: E/AndroidRuntime(5974): at android.app.ActivityThread.main(ActivityThread.java:4928)
05-10 03:41:52.687: E/AndroidRuntime(5974): at java.lang.reflect.Method.invokeNative(Native Method)
05-10 03:41:52.687: E/AndroidRuntime(5974): at java.lang.reflect.Method.invoke(Method.java:511)
05-10 03:41:52.687: E/AndroidRuntime(5974): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
05-10 03:41:52.687: E/AndroidRuntime(5974): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558)
05-10 03:41:52.687: E/AndroidRuntime(5974): at dalvik.system.NativeStart.main(Native Method)
05-10 03:41:52.687: E/AndroidRuntime(5974): Caused by: java.lang.NullPointerException
05-10 03:41:52.687: E/AndroidRuntime(5974): at com.uhi.fatfighter.MainActivity.initializeVariables(MainActivity.java:129)
05-10 03:41:52.687: E/AndroidRuntime(5974): at com.uhi.fatfighter.MainActivity.onCreate(MainActivity.java:86)
05-10 03:41:52.687: E/AndroidRuntime(5974): at android.app.Activity.performCreate(Activity.java:5008)
05-10 03:41:52.687: E/AndroidRuntime(5974): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
05-10 03:41:52.687: E/AndroidRuntime(5974): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2139)
05-10 03:41:52.687: E/AndroidRuntime(5974): ... 11 more