java.lang.ClassCastException : android. widget.TextView 无法转换为 android.widget.EditText

Question

我收到以下错误:

java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText at com.example.bmicalculator.MainActivity.initializeApp(MainActivity.java.32)

主要 Activity :

public class MainActivity extends Activity {

private EditText heightIn;
private EditText weightIn;
private Button CalculateButton;
private double weight =0;
private double height =0;
private TextView BmiResult;

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

    private void initializeApp() {
        heightIn = (EditText) findViewById (R.id.HeightInput1);
        weightIn = (EditText) findViewById (R.id.WeightInput1);
        CalculateButton = (Button) findViewById (R.id.CalculateButton);
        BmiResult = (TextView) findViewById (R.id.BmiResult);

    }

    public void calculateBMI(View v) {
        weight = Double.parseDouble(weightIn.getText().toString());
        height = Double.parseDouble(heightIn.getText().toString());
        double bmi = (weight / (height * height));
        String result = String.format("%.2f", bmi);
        Log.d("MyActivity", result);
        BmiResult.setText(result, TextView.BufferType.NORMAL);
    }
}

XML 文件:

<LinearLayout xmlns:tools="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/LinearLayout2"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
tools:context="${relativePackage}.${activityClass}" >

<TextView
    android:id="@+id/HeightInput1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/HeightInput"
    android:textAppearance="?android:attr/textAppearanceMedium" />

<EditText
    android:id="@+id/editText1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:ems="10"
    android:hint="@string/InchesHint"
    android:inputType="numberDecimal" >

    <requestFocus />
</EditText>

<TextView
    android:id="@+id/WeightInput1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/WeightInput"
    android:textAppearance="?android:attr/textAppearanceMedium" />

<EditText
    android:id="@+id/editText2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:ems="10"
    android:hint="@string/PoundsHint"
    android:inputType="numberDecimal" />

<Button
    android:id="@+id/CalculateButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="calculateBMI"
    android:text="@string/CalculateButton" />

<TextView
    android:id="@+id/BmiResult"
    android:layout_width="100dp"
    android:layout_height="0dp"
    android:layout_weight="0.00"
    android:text="@string/BmiResult" />

Answer 1

您的 heightIn 不是 EditText，并且您尝试将其转换为 EditText，因此出现错误

java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText at com.example.bmicalculator.MainActivity.initializeApp(MainActivity.java.32)

这样做，

heightIn = (TextView) findViewById (R.id.HeightInput1);
weightIn = (TextView) findViewById (R.id.WeightInput1);