Java 文本更改上的EditeText正在崩溃

我必须将一些数字文本转换为双精度文本，并在文本更改后执行简单的数学操作。除了文本更改外，一切正常：无论我做什么，它都会崩溃（也可以用“hello world”更改文本视图）

这是我的密码：

hEditText.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

        }

        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i1, int i2)
        {
            Double hDouble = Double.parseDouble(hEditText.toString());
            Double bDouble = Double.parseDouble(bEditText.toString());
            Double mDouble = Double.parseDouble(mEditText.getText().toString());
            Double miDouble = Double.parseDouble(miEditText.getText().toString());

            lResult.setText("" + Math.sqrt((hDouble * hDouble) + (bDouble * bDouble)));
        }

        @Override
        public void afterTextChanged(Editable editable) {

        }
    });

日志

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: com.example.cosmo.fisicapp, PID: 21198
              java.lang.NumberFormatException: empty String
                  at java.lang.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1071)
                  at java.lang.Double.parseDouble(Double.java:547)
                  at com.example.cosmo.fisicapp.Equilibrio$1.afterTextChanged(Equilibrio.java:47)
                  at android.widget.TextView.sendAfterTextChanged(TextView.java:8525)
                  at android.widget.TextView$ChangeWatcher.afterTextChanged(TextView.java:10788)
                  at android.text.SpannableStringBuilder.sendAfterTextChanged(SpannableStringBuilder.java:1222)
                  at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:583)
                  at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:509)
                  at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:508)
                  at android.text.method.NumberKeyListener.onKeyDown(NumberKeyListener.java:121)
                  at android.widget.TextView.doKeyDown(TextView.java:6533)
                  at android.widget.TextView.onKeyDown(TextView.java:6323)
                  at android.view.KeyEvent.dispatch(KeyEvent.java:2742)
                  at android.view.View.dispatchKeyEvent(View.java:9949)
                  at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
                  at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
                  at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
                  at android.widget.ScrollView.dispatchKeyEvent(ScrollView.java:391)
                  at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
                  at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
                  at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
                  at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
                  at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
                  at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
                  at com.android.internal.policy.DecorView.superDispatchKeyEvent(DecorView.java:439)
                  at com.android.internal.policy.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1861)
                  at android.app.Activity.dispatchKeyEvent(Activity.java:3141)
                  at android.support.v7.app.AppCompatActivity.dispatchKeyEvent(AppCompatActivity.java:535)
                  at android.support.v7.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:59)
                  at android.support.v7.app.AppCompatDelegateImpl$AppCompatWindowCallback.dispatchKeyEvent(AppCompatDelegateImpl.java:2530)
                  at com.android.internal.policy.DecorView.dispatchKeyEvent(DecorView.java:353)
                  at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:4742)
                  at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4713)
                  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4249)
                  at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4302)
                  at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4268)
                  at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4395)
                  at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4276)
                  at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4452)
                  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4249)
                  at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4302)
                  at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4268)
                  at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4276)
                  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4249)
                  at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:6676)
                  at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:6650)
                  at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6611)
                  at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:3917)
                  at android.os.Handler.dispatchMessage(Handler.java:105)
                  at android.os.Looper.loop(Looper.java:156)
                  at android.app.ActivityThread.main(ActivityThread.java:6523)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:942)

---

E/AndroidRuntime:com.android.internal.os.ZygoteInit.main（ZygoteInit.java:832）

尝试将代码移动到：

    @Override
    public void afterTextChanged(Editable editable) {
        Double hDouble = Double.parseDouble(hEditText.toString());
        Double bDouble = Double.parseDouble(bEditText.toString());
        Double mDouble = Double.parseDouble(mEditText.getText().toString());
        Double miDouble = Double.parseDouble(miEditText.getText().toString());

        lResult.setText("" + Math.sqrt((hDouble * hDouble) + (bDouble * bDouble)));
    }

---

正在尝试更改以下行：

Double hDouble=Double.parseDouble（hEditText.toString（））到
Double hDouble=Double.parseDouble（hEditText.getText（）.trim（））和其他行
每当解析器不生成双精度代码时，您的应用程序就会崩溃。在try/catch中包含从String到Double的每个转换。如果用户键入除数字或以外的任何内容，或清除编辑文本
然后应用程序将崩溃
方法
后文本更改
无法崩溃，因为它是空的。另一方面，方法
onTextChanged
，它广泛使用了
Double.parseDouble（String）
，因为如果您给它一些不能转换为Double的东西，这将抛出一个
NumberFormatException
。看

为了避免这种情况，一种可能是创建一个helper方法，这样您就不会到处放置
try-catch
块，而是决定捕获异常并返回默认值（例如
0D
），或者让它传播

例如：

private double toDouble(String raw) {
    double val;
    try {
        val = Double.parseDouble(raw);
    } catch (NumberFormatException e) {
        val = 0D;
    }
    return val;
}

然后
onTextChanged
中的代码变为

    @Override
    public void onTextChanged(CharSequence charSequence, int i, int i1, int i2)
    {
        Double hDouble = toDouble(hEditText.toString());
        Double bDouble = toDouble(bEditText.toString());
        Double mDouble = toDouble(mEditText.getText().toString());
        Double miDouble = toDouble(miEditText.getText().toString());

        lResult.setText("" + Math.sqrt((hDouble * hDouble) + (bDouble * bDouble)));
    }

添加崩溃日志？请在这里发布您的logcat堆栈跟踪。我想您的意思是说onTextChanged（）不断崩溃，对吗？因为您的PostTextChanged（）是空的，所以我在文本更改上的意思是，我添加了日志！文本字段是唯一的数字，在解析更改
val=Double.parseDouble（val）之前，请在
editText.getText（）.toString（）.isEmpty（）时进行检查到
val=Double.parseDouble（原始）@Arfmann我已经更新了我的答案。由于mTak指出的打字错误，它无法工作。
hEditText.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

        }

        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i1, int i2)
        {
          if(!charSequence.equals("")){
            Double hDouble = Double.parseDouble(charSequence.toString());
            Double bDouble = Double.parseDouble(charSequence.toString());
            Double mDouble = Double.parseDouble(charSequence.getText().toString());
            Double miDouble = Double.parseDouble(charSequence.getText().toString());

            lResult.setText("" + Math.sqrt((hDouble * hDouble) + (bDouble * bDouble)));
           }
        }

        @Override
        public void afterTextChanged(Editable editable) {

        }
    });