應用程序崩潰顯示NumberFormatException：無法在Android中解析''作爲整數？

Question

在我的應用程序中，我使用match.group（int group）方法返回匹配給定正則表達式組的文本，其中「match」是Matcher對象。但運行應用程序後，我得到一個NumberFormatException。在使用match.group（）方法之前，我嘗試使用match.find（）和match.matches（）方法，但隨後出現IllegalStateException並且應用程序再次崩潰。

這是我的代碼：

public int getProgramNumberInt() { 
    Matcher m = PROGRAM_NUMBER_INT_PATTERN.matcher(programNumber); 
    return m.matches() ? Integer.parseInt(m.group(1)) : 0; 
} 

墜機發生在這一行：

return m.matches() ? Integer.parseInt(m.group(1)) : 0; 

的logcat：

04-23 15:45:25.096: E/AndroidRuntime(16260): FATAL EXCEPTION: main 
04-23 15:45:25.096: E/AndroidRuntime(16260): java.lang.NumberFormatException: unable to parse '' as integer 
04-23 15:45:25.096: E/AndroidRuntime(16260): at java.lang.Integer.parseInt(Integer.java:412) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at java.lang.Integer.parseInt(Integer.java:382) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at com.example.Matcher.getProgramNumberInt(Starter.java:101) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at com.example.Matcher.results.ResultsActivity$Adapter.getPayoffView(ResultsActivity.java:127) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at com.example.Matcher.results.ResultsActivity$Adapter.getView(ResultsActivity.java:62) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.AbsListView.obtainView(AbsListView.java:1294) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.ListView.measureHeightOfChildren(ListView.java:1198) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.ListView.onMeasure(ListView.java:1109) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1012) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.LinearLayout.measureVertical(LinearLayout.java:381) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.LinearLayout.onMeasure(LinearLayout.java:304) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1012) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.LinearLayout.measureVertical(LinearLayout.java:381) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.LinearLayout.onMeasure(LinearLayout.java:304) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.View.measure(View.java:8171) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewRoot.performTraversals(ViewRoot.java:801) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.view.ViewRoot.handleMessage(ViewRoot.java:1727) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.os.Handler.dispatchMessage(Handler.java:99) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.os.Looper.loop(Looper.java:123) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at android.app.ActivityThread.main(ActivityThread.java:4627) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at java.lang.reflect.Method.invokeNative(Native Method) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at java.lang.reflect.Method.invoke(Method.java:521) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
04-23 15:45:25.096: E/AndroidRuntime(16260): at dalvik.system.NativeStart.main(Native Method) 

可否請你讓我知道如果有什麼辦法防止應用程序崩潰並解決此問題？ 謝謝。

Answer 1

方法m.group(1)返回''空字符串。所以parseInt()方法要花費NumberFormatException。