从 EditText 获取数字

Question

我知道他已经被问过几次了，但我一直在尝试我找到的所有东西，但没有运气。我仍然有一个错误。这是我的代码。

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

我试图从 EditText 中获取一个 int，然后在其他类中使用它来确定某物的值。谁能告诉我我做错了什么？

谢谢

Answer 1

例外是：

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

这只是因为editbox1字段中没有值。

@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());
    }
}

Answer 2

代码试图将 EditText '' 中的空字符串解析为 int，这会导致引发异常。

您的示例代码也缺少结束 LinearLayout 标记。

Answer 3

您尝试访问valor1 太快，valor1 当前是一个空字符串。您必须在用户有机会定义某些内容后处理该值。

尝试添加这样的按钮：

(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);
        }
    }
}

Answer 4

使用正则表达式...如下：

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]",""));

}

}

Answer 5

您上面的代码肯定会引起问题，因为您在onCreate() 中做了Integer.parseInt(myEditValue)，在创建Activity 时，您的EditText 尚未填充任何文本（并且您没有提供默认值在其 XML 定义中），所以它是一个空字符串，Integer.parseInt(emptyString) 将抛出 NumberFormatException。

执行此操作的正确方法是将解析 EditText 值的代码移动到某个地方，以响应用户事件，或者只是 try...catchInteger.parseInt()。

最安全的方法永远是try...catchInteger.parseInt()，因为我们应该永远不要相信用户的输入。