java.lang.ClassCastException：android.widget.TextView無法轉換為android.widget.EditText

Question

我收到以下錯誤：

java.lang.ClassCastException：android.widget.TextView無法轉換為com.example.bmicalculator.MainActivity.initializeApp（MainActivity.java.32）上的android.widget.EditText

主要活動：

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檔案：

<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並且您嘗試將其heightIn為EditText因此出現錯誤

java.lang.ClassCastException：android.widget.TextView無法轉換為com.example.bmicalculator.MainActivity.initializeApp（MainActivity.java.32）上的android.widget.EditText

這樣做

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

Answer 2

更改此：

<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" />

通過

<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" />

要么

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

通過

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" />

因此，請根據您的要求進行更改。

Answer 4

1. 有兩種可能性，HeightInput1 id組件應該是Edit text不是text view
2. else在代碼中，將“編輯文本”更改為ID為HeightInput1的“文本”視圖

所以用這個改變java代碼

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

否則在xml文件中更改

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

Answer 5

在Xml文件中，您將聲明為TextView，並且嘗試將TextView解析為EditText，這就是為什么您獲得異常的原因。

更改EditText變量

private EditText heightIn;
private EditText weightIn;

至

private TextView heightIn;
private TextView weightIn;

並將您的initializeApp（）函數替換為：

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 6

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

在這里，您將heightIn稱為EditTect，在layout.xml中將其稱為TextView，
而不是找到只是要標記的文本“ HeightInput1”，它應該找到EditText

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

與重量輸入相同...祝您好運！