仿真器沒有輸入後crahses

我對Java和Android應用程序非常新，我正在創建一個簡單的計算器，一切都很順利，但我發現了一個問題，那就是當我只是按例如乘以沒有數字的地方我的模擬器會崩潰，我失蹤某種鱈魚在我的聽衆，但無法找出什麼以及它放在這裏是我的MainActivity，爪哇：仿真器沒有輸入後crahses

package com.firstprogram; 

    import android.os.Bundle; 
    import android.app.Activity; 
    import android.text.InputType; 
    import android.util.TypedValue; 
    import android.view.Gravity; 
    import android.view.View; 
    import android.widget.Button; 
    import android.widget.EditText; 
    import android.widget.LinearLayout; 
    import android.widget.TextView; 


    public class MainActivity extends Activity { 

    LinearLayout layout1; 
    LinearLayout buttonLayout; 
    EditText number1text; 
    EditText number2text; 
    Button multiplyButton; 
    Button divideButton; 
    Button addButton; 
    Button subButton; 
    TextView answerText; 


    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     layout1 = new LinearLayout (this); 
     buttonLayout = new LinearLayout (this); 
     number1text = new EditText (this); 
     number2text = new EditText (this); 
     multiplyButton = new Button (this); 
     divideButton = new Button (this); 
     addButton = new Button (this); 
     subButton = new Button (this); 
     answerText = new TextView (this); 

     answerText.setTextSize(TypedValue.COMPLEX_UNIT_SP,28); 

     layout1.setOrientation(LinearLayout.VERTICAL); 
     layout1.setGravity(Gravity.CENTER_HORIZONTAL); 
     buttonLayout.setOrientation(LinearLayout.HORIZONTAL); 
     buttonLayout.setGravity(Gravity.CENTER_HORIZONTAL); 

     number1text.setInputType(InputType.TYPE_CLASS_NUMBER); 
     number2text.setInputType(InputType.TYPE_CLASS_NUMBER); 

     answerText.setGravity(Gravity.CENTER_HORIZONTAL); 
     answerText.setText("0"); 
     multiplyButton.setText("X"); 
     divideButton.setText("/"); 
     addButton.setText("+"); 
     subButton.setText("-"); 

     multiplyButton.setOnClickListener((android.view.View.OnClickListener) multiplyClicked); 
     divideButton.setOnClickListener((android.view.View.OnClickListener) divideClicked); 
     addButton.setOnClickListener((android.view.View.OnClickListener) addClicked); 
     subButton.setOnClickListener((android.view.View.OnClickListener) subClicked); 

     buttonLayout.addView(multiplyButton); 
     buttonLayout.addView(divideButton); 
     buttonLayout.addView(addButton); 
     buttonLayout.addView(subButton); 

     layout1.addView(number1text); 
     layout1.addView(number2text); 
     layout1.addView(buttonLayout); 
     layout1.addView(answerText); 


     setContentView(layout1); 

     number1text.setLayoutParams(new LinearLayout.LayoutParams(500,50)); 
     number2text.setLayoutParams(new LinearLayout.LayoutParams(500,50)); 
     multiplyButton.setLayoutParams(new LinearLayout.LayoutParams(50,50)); 
     divideButton.setLayoutParams(new LinearLayout.LayoutParams(50,50)); 
     addButton.setLayoutParams(new LinearLayout.LayoutParams(50,50)); 
     subButton.setLayoutParams(new LinearLayout.LayoutParams(50,50)); 
    } 

    private View.OnClickListener multiplyClicked = new View.OnClickListener() { 

     @Override 
     public void onClick (View v){ 
      String firstString = number1text.getText().toString(); 
      String secondString = number2text.getText().toString(); 
      double firstNumber = Double.parseDouble(firstString); 
      double secondNumber = Double.parseDouble(secondString); 
      double result = firstNumber * secondNumber; 
      String resultString = String.valueOf(result); 
      answerText.setText(resultString); 
     } 
    }; 

private View.OnClickListener divideClicked = new View.OnClickListener() { 

     @Override 
     public void onClick (View v){ 
      String firstString = number1text.getText().toString(); 
      String secondString = number2text.getText().toString(); 
      double firstNumber = Double.parseDouble(firstString); 
      double secondNumber = Double.parseDouble(secondString); 
      if(secondNumber!=0) { 
      double result = firstNumber/secondNumber; 
      String resultString = String.valueOf(result); 
      answerText.setText(resultString); 
      } 
     } 
    }; 

private View.OnClickListener addClicked = new View.OnClickListener() { 

     @Override 
     public void onClick (View v){ 
      String firstString = number1text.getText().toString(); 
      String secondString = number2text.getText().toString(); 
      double firstNumber = Double.parseDouble(firstString); 
      double secondNumber = Double.parseDouble(secondString); 
      double result = firstNumber + secondNumber; 
      String resultString = String.valueOf(result); 
      answerText.setText(resultString); 
     } 
    }; 

private View.OnClickListener subClicked = new View.OnClickListener() { 

     @Override 
     public void onClick (View v){ 
      String firstString = number1text.getText().toString(); 
      String secondString = number2text.getText().toString(); 
      double firstNumber = Double.parseDouble(firstString); 
      double secondNumber = Double.parseDouble(secondString); 
      double result = firstNumber - secondNumber; 
      String resultString = String.valueOf(result); 
      answerText.setText(resultString); 
     } 
    }; 



}

這裏是logcat的：

08-23 07:15:06.241: D/gralloc_goldfish(792): Emulator without GPU emulation detected. 
08-23 07:15:15.631: D/dalvikvm(792): GC_FOR_ALLOC freed 257K, 14% free 2762K/3176K, paused 50ms, total 63ms 
08-23 07:20:06.893: D/gralloc_goldfish(850): Emulator without GPU emulation detected. 
08-23 07:21:21.171: I/Choreographer(850): Skipped 33 frames! The application may be doing too much work on its main thread. 
08-23 07:21:30.881: I/Choreographer(850): Skipped 31 frames! The application may be doing too much work on its main thread. 
08-23 07:23:39.641: D/gralloc_goldfish(893): Emulator without GPU emulation detected. 
08-23 07:29:47.051: I/Choreographer(893): Skipped 42 frames! The application may be doing too much work on its main thread. 
08-23 07:37:02.152: I/Choreographer(893): Skipped 35 frames! The application may be doing too much work on its main thread. 
08-23 07:38:16.154: D/gralloc_goldfish(936): Emulator without GPU emulation detected. 
08-23 07:51:40.516: I/Choreographer(936): Skipped 72 frames! The application may be doing too much work on its main thread. 
08-23 07:53:47.001: I/Choreographer(936): Skipped 58 frames! The application may be doing too much work on its main thread. 
08-23 08:22:32.431: I/Choreographer(936): Skipped 32 frames! The application may be doing too much work on its main thread. 
08-23 08:36:53.827: I/Choreographer(936): Skipped 54 frames! The application may be doing too much work on its main thread. 
08-23 08:51:51.864: I/Choreographer(936): Skipped 54 frames! The application may be doing too much work on its main thread. 
08-23 08:56:47.101: I/Choreographer(936): Skipped 34 frames! The application may be doing too much work on its main thread. 
08-23 08:57:40.044: I/Choreographer(936): Skipped 42 frames! The application may be doing too much work on its main thread. 
08-23 09:07:14.461: I/Choreographer(936): Skipped 48 frames! The application may be doing too much work on its main thread. 
08-23 09:08:47.069: I/Choreographer(936): Skipped 32 frames! The application may be doing too much work on its main thread. 
08-23 09:14:26.301: D/gralloc_goldfish(1109): Emulator without GPU emulation detected. 
08-23 09:14:31.151: D/AndroidRuntime(1109): Shutting down VM 
08-23 09:14:31.151: W/dalvikvm(1109): threadid=1: thread exiting with uncaught exception (group=0x414c4700) 
08-23 09:14:31.231: E/AndroidRuntime(1109): FATAL EXCEPTION: main 
08-23 09:14:31.231: E/AndroidRuntime(1109): java.lang.NumberFormatException: Invalid double: "" 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at java.lang.StringToReal.invalidReal(StringToReal.java:63) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at java.lang.StringToReal.parseDouble(StringToReal.java:248) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at java.lang.Double.parseDouble(Double.java:295) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at com.firstprogram.MainActivity$2.onClick(MainActivity.java:93) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at android.view.View.performClick(View.java:4240) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at android.view.View$PerformClick.run(View.java:17721) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at android.os.Handler.handleCallback(Handler.java:730) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at android.os.Handler.dispatchMessage(Handler.java:92) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at android.os.Looper.loop(Looper.java:137) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at android.app.ActivityThread.main(ActivityThread.java:5103) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at java.lang.reflect.Method.invoke(Method.java:525) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
08-23 09:14:31.231: E/AndroidRuntime(1109):  at dalvik.system.NativeStart.main(Native Method) 
08-23 09:14:31.321: D/dalvikvm(1109): GC_FOR_ALLOC freed 243K, 13% free 2776K/3176K, paused 57ms, total 73ms 
08-23 09:14:51.461: D/gralloc_goldfish(1152): Emulator without GPU emulation detected. 
08-23 09:21:59.242: I/Choreographer(1152): Skipped 39 frames! The application may be doing too much work on its main thread. 
08-23 09:27:10.061: I/Choreographer(1152): Skipped 69 frames! The application may be doing too much work on its main thread. 
08-23 09:42:37.441: D/gralloc_goldfish(1211): Emulator without GPU emulation detected. 
08-23 09:48:27.291: D/gralloc_goldfish(1258): Emulator without GPU emulation detected. 
08-23 09:48:34.741: D/dalvikvm(1258): GC_FOR_ALLOC freed 240K, 13% free 2779K/3176K, paused 68ms, total 76ms 
08-23 09:51:57.135: I/Choreographer(1258): Skipped 97 frames! The application may be doing too much work on its main thread. 
08-23 09:59:16.411: I/Choreographer(1258): Skipped 38 frames! The application may be doing too much work on its main thread. 
08-23 09:59:21.872: D/AndroidRuntime(1258): Shutting down VM 
08-23 09:59:21.872: W/dalvikvm(1258): threadid=1: thread exiting with uncaught exception (group=0x414c4700) 
08-23 09:59:21.991: E/AndroidRuntime(1258): FATAL EXCEPTION: main 
08-23 09:59:21.991: E/AndroidRuntime(1258): java.lang.NumberFormatException: Invalid double: "" 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at java.lang.StringToReal.invalidReal(StringToReal.java:63) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at java.lang.StringToReal.parseDouble(StringToReal.java:248) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at java.lang.Double.parseDouble(Double.java:295) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at com.firstprogram.MainActivity$1.onClick(MainActivity.java:91) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at android.view.View.performClick(View.java:4240) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at android.view.View$PerformClick.run(View.java:17721) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at android.os.Handler.handleCallback(Handler.java:730) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at android.os.Handler.dispatchMessage(Handler.java:92) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at android.os.Looper.loop(Looper.java:137) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at android.app.ActivityThread.main(ActivityThread.java:5103) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at java.lang.reflect.Method.invoke(Method.java:525) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
08-23 09:59:21.991: E/AndroidRuntime(1258):  at dalvik.system.NativeStart.main(Native Method) 
08-23 09:59:25.653: I/Process(1258): Sending signal. PID: 1258 SIG: 9 
08-23 09:59:51.091: D/gralloc_goldfish(1314): Emulator without GPU emulation detected. 
08-23 09:59:57.921: D/AndroidRuntime(1314): Shutting down VM 
08-23 09:59:57.921: W/dalvikvm(1314): threadid=1: thread exiting with uncaught exception (group=0x414c4700) 
08-23 09:59:58.061: D/dalvikvm(1314): GC_FOR_ALLOC freed 241K, 13% free 2778K/3176K, paused 62ms, total 70ms 
08-23 09:59:58.072: E/AndroidRuntime(1314): FATAL EXCEPTION: main 
08-23 09:59:58.072: E/AndroidRuntime(1314): java.lang.NumberFormatException: Invalid double: "" 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at java.lang.StringToReal.invalidReal(StringToReal.java:63) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at java.lang.StringToReal.parseDouble(StringToReal.java:248) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at java.lang.Double.parseDouble(Double.java:295) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at com.firstprogram.MainActivity$1.onClick(MainActivity.java:92) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at android.view.View.performClick(View.java:4240) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at android.view.View$PerformClick.run(View.java:17721) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at android.os.Handler.handleCallback(Handler.java:730) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at android.os.Handler.dispatchMessage(Handler.java:92) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at android.os.Looper.loop(Looper.java:137) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at android.app.ActivityThread.main(ActivityThread.java:5103) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at java.lang.reflect.Method.invoke(Method.java:525) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
08-23 09:59:58.072: E/AndroidRuntime(1314):  at dalvik.system.NativeStart.main(Native Method) 
08-23 10:00:00.761: I/Process(1314): Sending signal. PID: 1314 SIG: 9 
08-23 10:01:31.132: D/gralloc_goldfish(1365): Emulator without GPU emulation detected. 
08-23 10:01:47.221: D/dalvikvm(1365): GC_FOR_ALLOC freed 242K, 13% free 2777K/3176K, paused 77ms, total 85ms 
08-23 10:01:47.221: D/AndroidRuntime(1365): Shutting down VM 
08-23 10:01:47.232: W/dalvikvm(1365): threadid=1: thread exiting with uncaught exception (group=0x414c4700) 
08-23 10:01:47.281: E/AndroidRuntime(1365): FATAL EXCEPTION: main 
08-23 10:01:47.281: E/AndroidRuntime(1365): java.lang.NumberFormatException: Invalid double: "" 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at java.lang.StringToReal.invalidReal(StringToReal.java:63) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at java.lang.StringToReal.parseDouble(StringToReal.java:248) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at java.lang.Double.parseDouble(Double.java:295) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at com.firstprogram.MainActivity$1.onClick(MainActivity.java:92) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at android.view.View.performClick(View.java:4240) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at android.view.View$PerformClick.run(View.java:17721) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at android.os.Handler.handleCallback(Handler.java:730) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at android.os.Handler.dispatchMessage(Handler.java:92) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at android.os.Looper.loop(Looper.java:137) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at android.app.ActivityThread.main(ActivityThread.java:5103) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at java.lang.reflect.Method.invoke(Method.java:525) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
08-23 10:01:47.281: E/AndroidRuntime(1365):  at dalvik.system.NativeStart.main(Native Method) 
08-23 10:01:49.873: I/Process(1365): Sending signal. PID: 1365 SIG: 9

來源

2013-08-23 Antony

你需要在這裏發佈LogCat的輸出。 – chrylis

你的應用程序崩潰或整個模擬器（窗口消失）？ – Henry

我已經添加了LogCat，也只是應用程序崩潰 – Antony

在您的聽衆onClick，您正在抓取中的文字和number2text並試圖將它們轉換爲Double s。如果這些字符串是空的（或者用戶輸入的內容類似「hello，there！」），則系統不能將字符串轉換爲數字，您將得到一個NumberFormatException。這幾乎可以肯定這裏發生了什麼，儘管LogCat的輸出應該指定。

您需要將所有parseDouble調用包裝在try...catch區塊中並採取適當的措施（例如彈出「我不能那樣做，戴夫」，然後不繼續）。

來源

2013-08-23 14:18:52 chrylis

您可以簡單地在每個按鈕偵聽器中放入if語句，這些語句會檢查是否給出了數字。如果字符串是「」，那麼parseDouble將失敗，這就是爲什麼你會收到錯誤。

例如：

private View.OnClickListener multiplyClicked = new View.OnClickListener() { 

    @Override 
    public void onClick (View v){ 
     String firstString = number1text.getText().toString(); 
     String secondString = number2text.getText().toString(); 

     if (firstString != NULL && secondString != NULL) { // Checks strings aren't null 
      double firstNumber = Double.parseDouble(firstString); 
      double secondNumber = Double.parseDouble(secondString); 
      double result = firstNumber * secondNumber; 
      String resultString = String.valueOf(result); 
      answerText.setText(resultString); 
     } else { 
      // Do something eg. print "Can't do that!" 
     } 
    } 
};

來源

2013-08-23 14:35:08

這將解決眼前的問題，但不是如果有人輸入一個非空字符串仍然不是有效的數字（類似'1.1.1.1'也是可能的一個數字鍵盤）。捕獲'NumberFormatException'更可靠。 – chrylis

是的你是對的，我沒有想到這種情況。按照您的回答建議，嘗試/抓住要好得多 –

java.lang.NumberFormatException: Invalid double: ""

這就是問題所在。

之前你乘或做任何操作，你需要檢查輸入是否爲空或空，並且還可以檢查它是否是一個數字或沒有（即使用戶將只能輸入數字）

來源

2013-08-23 14:39:18 Susie

仿真器沒有輸入後crahses

回答

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