嘗試捕捉按鈕的Android

Question

我試圖建立嘗試捕捉異常，當edit1，2，3 = "";

public void OnClick(View v) { 

    int a, d, n; 
    String text = ""; 
    a = Integer.valueOf(edit1.getText().toString()); 
    d = Integer.valueOf(edit2.getText().toString()); 
    n = Integer.valueOf(edit3.getText().toString()); 

    try { 
     for (int i = 1; i <= n; i++) { 
      textView.setText(text += String.valueOf(a + (i - 1) * d + " ")); 
     } 
    } catch (IllegalStateException e) { 
     Toast toast = Toast.makeText(getApplicationContext(), 
       "Не заданы данные!", Toast.LENGTH_SHORT); 
     toast.show(); 
    } 

而且有compilator：

FATAL EXCEPTION: main 
    java.lang.IllegalStateException: Could not execute method for android:onClick 
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:275) 
    at android.view.View.performClick(View.java:4204) 
    at android.view.View$PerformClick.run(View.java:17355) 
    at android.os.Handler.handleCallback(Handler.java:725) 
    at android.os.Handler.dispatchMessage(Handler.java:92) 
    at android.os.Looper.loop(Looper.java:137) 
    at android.app.ActivityThread.main(ActivityThread.java:5041) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:511) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
    at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.reflect.InvocationTargetException 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:511) 
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:270) 
    at android.view.View.performClick(View.java:4204)  
    at android.view.View$PerformClick.run(View.java:17355)  
    at android.os.Handler.handleCallback(Handler.java:725)  
    at android.os.Handler.dispatchMessage(Handler.java:92)  
    at android.os.Looper.loop(Looper.java:137)  
    at android.app.ActivityThread.main(ActivityThread.java:5041)  
    at java.lang.reflect.Method.invokeNative(Native Method)  
    at java.lang.reflect.Method.invoke(Method.java:511)  
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)  
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)  
    at dalvik.system.NativeStart.main(Native Method)  
Caused by: java.lang.NumberFormatException: Invalid int: "" 
    at java.lang.Integer.invalidInt(Integer.java:138) 
    at java.lang.Integer.parseInt(Integer.java:359) 
    at java.lang.Integer.parseInt(Integer.java:332) 
    at java.lang.Integer.valueOf(Integer.java:490) 
    at cmplxt.p_4.MainActivity.OnClick(MainActivity.java:32) 
    at java.lang.reflect.Method.invokeNative(Native Method)  
    at java.lang.reflect.Method.invoke(Method.java:511)  
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:270)  
    at android.view.View.performClick(View.java:4204)  
    at android.view.View$PerformClick.run(View.java:17355)  
    at android.os.Handler.handleCallback(Handler.java:725)  
    at android.os.Handler.dispatchMessage(Handler.java:92)  
    at android.os.Looper.loop(Looper.java:137)  
    at android.app.ActivityThread.main(ActivityThread.java:5041)  
    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:793)  
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)  
    at dalvik.system.NativeStart.main(Native Method)  

Answer 1

你得到一個java.lang.NumberFormatException ：無效的int：「」。您不能將空字符串轉換爲整數。您應該在catch塊中添加「java.lang.NumberFormatException」，或者在嘗試轉換之前檢查String是否爲空。