Get numbers from EditText

问题:

I know that his have been asked a few times, but I have been trying everything I have found with no luck. I'm still having a error. Here's my code.

xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="center"
android:background="@android:color/transparent"
android:gravity="center"
android:orientation="vertical" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Write item value."
    android:textColor="@android:color/black"
    android:textSize="25dp" />

<EditText
    android:id="@+id/editText1"
    android:layout_width="80dp"
    android:layout_height="wrap_content"
    android:layout_marginBottom="202dp"
    android:ems="10"
    android:hint="Value"
    android:inputType="number" >

    <requestFocus />
</EditText>

java

public class PopupValores extends Activity {

    EditText valor1;
    String myEditValue;
    public static int valor;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.popupvalores);

        valor1 = (EditText) findViewById (R.id.editText1);
        myEditValue = valor1.getText().toString();
        valor = Integer.parseInt(myEditValue);   <<<<Line 20

    }
}

LogCat

05-08 21:02:10.023: W/dalvikvm(6074): threadid=1: thread exiting with uncaught exception (group=0x40020578)
05-08 21:02:10.039: E/AndroidRuntime(6074): FATAL EXCEPTION: main
05-08 21:02:10.039: E/AndroidRuntime(6074): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.dc.maker/com.dc.maker.PopupValores}: java.lang.NumberFormatException: unable to parse '' as integer
05-08 21:02:10.039: E/AndroidRuntime(6074):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at android.os.Looper.loop(Looper.java:130)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at android.app.ActivityThread.main(ActivityThread.java:3687)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at java.lang.reflect.Method.invokeNative(Native Method)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at java.lang.reflect.Method.invoke(Method.java:507)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at dalvik.system.NativeStart.main(Native Method)
05-08 21:02:10.039: E/AndroidRuntime(6074): Caused by: java.lang.NumberFormatException: unable to parse '' as integer
05-08 21:02:10.039: E/AndroidRuntime(6074):     at java.lang.Integer.parseInt(Integer.java:362)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at java.lang.Integer.parseInt(Integer.java:332)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at com.popupclass.PopupValores.onCreate(PopupValores.java:20)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-08 21:02:10.039: E/AndroidRuntime(6074):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
05-08 21:02:10.039: E/AndroidRuntime(6074):     ... 11 more

I'm trying to get a int from the EditText and then use it in other class to determinate a value of something. Can someone tell me what I'm doing wrong?

Thanks

回答1:

The exception is:

Java.lang.NumberFormatException: unable to parse '' as integer

And it's only because there is no value in the editbox1 field.

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.popupvalores);

    valor1 = (EditText) findViewById (R.id.editText1);
    myEditValue = valor1.getText().toString();

    Log.debug("logtag", myEditValue); // Here you can see the output.

    try {
        valor = Integer.parseInt(myEditValue); 
    }
    catch(Exception e) {
        Log.e("logtag", "Exception: " + e.toString());
    }
}

回答2:

The code is trying to parse an empty string from the EditText '' as an int which causes an exception to be thrown.

Your example code is also missing the closing LinearLayout tag.

回答3:

You are trying to access valor1 too soon, valor1 is currently an empty string. You must process the value after to user has had a chance to define something.

Try adding a button like this:

(Button) button = (Button) findViewByID(R.id.button1);
button.setOnClickListener(new OnClickListener() {
    public void onClick(View view) {
        String temp = valor1.getText().toString();
        if(temp.isEmpty() == false) {
            valor = Integer.parseInt(temp);
            Log.v("SO", "Valor = " + valor);
        }
    }
}

回答4:

Use regular expression...below:

public class PopupValores extends Activity {

EditText valor1;
String myEditValue;
public static int valor;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.popupvalores);

    valor1 = (EditText) findViewById (R.id.editText1);
    myEditValue = valor1.getText().toString();
    valor = Integer.parseInt(myEditValue.replaceAll("[\\D]",""));

}

}

回答5:

Your code above will definitely cause problem, because you did Integer.parseInt(myEditValue) in onCreate(), at the time your Activity is being created, your EditText is not yet filled with any text(and you didn't provide a default value in its XML definition), so it is an empty string, and Integer.parseInt(emptyString) will throw NumberFormatException.

The correct way to doing this is moving the code parsing the value of EditText to somewhere, where in response to user events, or simply try...catch Integer.parseInt().

The safest way is always to try...catch Integer.parseInt(), because we should Never Trust user's input.