java.lang.ClassCastException: android.widget.TextView 不能转换为 android.widget.EditText

Question

我收到以下错误：

java.lang.ClassCastException: android.widget.TextView 不能被强制转换 到 android.widget.EditText 在 com.example.bmicalculator.MainActivity.initializeApp(MainActivity.java.32)

主要活动：

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 所以您收到错误

java.lang.ClassCastException: android.widget.TextView 不能 投射到 android.widget.EditText 在 com.example.bmicalculator.MainActivity.initializeApp(MainActivity.java.32)

照做，

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

Answer 2

改变这个：

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

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

通过

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

或

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

通过

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

Answer 3

在java文件中

heightIn = (EditText) findViewById (R.id.HeightInput1);

和

在xml文件中

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

所以根据你的要求改变。

Answer 4

在 Xml 文件中，您被声明为 TextView，并且您正在尝试将 TextView 解析为 EditText，这就是您收到异常的原因。

更改 EditText 变量

private EditText heightIn;
private EditText weightIn;

到

private TextView heightIn;
private TextView weightIn;

并将您的 initializeApp() 函数替换为：

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

}

Answer 5

 heightIn = (EditText) findViewById (R.id.HeightInput1);

您在这里提到 heightIn 为 EditTect，在您的 layout.xml 中它为 TextView，
而不是找到“HeightInput1”，它只是你要标记的文本，它应该找到 EditText

 heightIn = (EditText) findViewById (R.id.EditText1);   

与权重输入相同...祝你好运！

Answer 6

1. 有两种可能，HeightInput1 id 组件应该是编辑文本而不是文本视图
2. else 在代码中将编辑文本更改为 id 为 HeightInput1 的文本视图

所以改变 带有这个的java代码

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

用这个改变xml文件

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