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這裏是生成錯誤「08-02 19：17：22.265：E/AndroidRuntime（17817）：java.lang.ClassCastException：android.widget.RelativeLayout無法轉換爲android.widget.TextView」LogCat錯誤，爲什麼會發生這種情況？
package tip.calculator;
import android.os.Bundle;
import android.app.Activity;
import android.text.TextUtils;
import android.view.View.OnClickListener;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import android.view.View;
import android.widget.Button;
public class TipCalculator extends Activity
{
private Button enter;
EditText myEditField ;
EditText myEditField2;
float percentage = 0;
float percentageInp = 0;
float billAmount = 0;
double output = 0;
String output1 = "";
Button clearButton ;
TextView textView;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myEditField = (EditText) findViewById(R.id.percentText);
enter = (Button)findViewById(R.id.button1);
myEditField2 = (EditText) findViewById(R.id.billText);
clearButton = (Button) findViewById(R.id.clearButton);
enter.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
TextView errors;
textView = (TextView) findViewById(R.id.textView1);
errors = (TextView) findViewById(R.id.errorText);
if((myEditField2 != null) && (!TextUtils.isEmpty(myEditField2.getText().toString()))){
percentageInp = Float.parseFloat(myEditField.getText().toString());
billAmount = Float.parseFloat(myEditField2.getText().toString());
percentage = ((float)percentageInp /100);
output = (double)(billAmount * percentage);
double result = output * 100;
result = Math.round(result);
result = result/100;
output1 = Double.toString(result);
textView.setText(output1 + " $");
} else{
//Toast.makeToast(.....).show(); //Inform user about the error
}
}
});
clearButton.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
percentage = 0;
output = 0;
output1 = "";
TextView textView = (TextView)findViewById(R.id.errorText);
textView.setText("");
TextView textView2 = (TextView)findViewById(R.id.percentText);
textView2.setText("");
TextView textView3 = (TextView)findViewById(R.id.billText);
textView3.setText("");
TextView textView1 = (TextView)findViewById(R.id.textView1);
textView1.setText("");
percentageInp = 0;
billAmount = 0;
myEditField.clearComposingText();
myEditField2.clearComposingText();
}
});
}
}
這裏是logcat的錯誤，我不明白爲什麼它發生......
08-02 19:17:22.265: E/AndroidRuntime(17817): java.lang.ClassCastException: android.widget.RelativeLayout cannot be cast to android.widget.TextView
08-02 19:17:22.265: E/AndroidRuntime(17817): at tip.calculator.TipCalculator$1.onClick(TipCalculator.java:48)
08-02 19:17:22.265: E/AndroidRuntime(17817): at android.view.View.performClick(View.java:3620)
08-02 19:17:22.265: E/AndroidRuntime(17817): at android.view.View$PerformClick.run(View.java:14292)
08-02 19:17:22.265: E/AndroidRuntime(17817): at android.os.Handler.handleCallback(Handler.java:605)
08-02 19:17:22.265: E/AndroidRuntime(17817): at android.os.Handler.dispatchMessage(Handler.java:92)
08-02 19:17:22.265: E/AndroidRuntime(17817): at android.os.Looper.loop(Looper.java:137)
08-02 19:17:22.265: E/AndroidRuntime(17817): at android.app.ActivityThread.main(ActivityThread.java:4507)
08-02 19:17:22.265: E/AndroidRuntime(17817): at java.lang.reflect.Method.invokeNative(Native Method)
08-02 19:17:22.265: E/AndroidRuntime(17817): at java.lang.reflect.Method.invoke(Method.java:511)
08-02 19:17:22.265: E/AndroidRuntime(17817): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
08-02 19:17:22.265: E/AndroidRuntime(17817): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
08-02 19:17:22.265: E/AndroidRuntime(17817): at dalvik.system.NativeStart.main(Native Method)
這裏是所有的textViews和這樣的遺憾了好一會兒的XML ...
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/errorText"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:onClick="onEnterClick" >
<EditText
android:id="@+id/billText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:ems="10"
android:hint="Bill Amount"
android:inputType="numberDecimal"
android:singleLine="true" />
<EditText
android:id="@+id/percentText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/billText"
android:layout_below="@+id/billText"
android:ems="10"
android:hint="Percent"
android:inputType="number"
android:singleLine="true" >
<requestFocus />
</EditText>
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/percentText"
android:layout_centerHorizontal="true"
android:text="Calculate" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/percentText"
android:layout_toRightOf="@+id/billText"
android:text="$"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/percentText"
android:layout_alignLeft="@+id/textView2"
android:text="%"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="@+id/clearButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/button1"
android:layout_centerHorizontal="true"
android:text="Clear" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignRight="@+id/textView3"
android:layout_below="@+id/clearButton"
android:text="Solution Will Appear Here"
android:textAppearance="?android:attr/textAppearanceLarge" />
</RelativeLayout>
什麼是線48 TipCalculator.java？ – Sam 2012-08-03 02:32:12