java.lang.ClassCastException:android.widget.TextView。 为什么我得到这个?

出于某种原因,我得到一个ClassCastException错误。 我不知道为什么。

在此先感谢,我是一个新的程序员,任何帮助将真正帮助(没有双关语意)。

码:

final EditText answerBox = (EditText) findViewById(R.id.answerBox); final Button button = (Button) findViewById(R.id.button); final TextView problem = (TextView) findViewById(R.id.problem); final TextView status = (TextView) findViewById(R.id.status); final TextView num = (TextView) findViewById(R.id.numerator); final TextView denom = (TextView) findViewById(R.id.denominator); button.setOnClickListener(new OnClickListener() { private String inputString; public void onClick(View v) { inputString = problem.getText().toString(); int firstNumber = Integer.parseInt(inputString.substring(0,1)); int secondNumber = Integer.parseInt(inputString.substring(2,3)); int correct = firstNumber + secondNumber; int input; if(!answerBox.getText().toString().equals("")) input = Integer.parseInt(answerBox.getText().toString()); else input = -1; if(input != -1) { if(input == correct) { status.setText("Nice! You are correct!"); denom.setText(Integer.parseInt(denom.getText().toString()) +1); num.setText(Integer.parseInt(num.getText().toString()) +1); } else { status.setText("Sorry, but your answer was wrong."); denom.setText(Integer.parseInt(denom.getText().toString()) +1); } } int a = (int) (Math.random() * 10); int b = (int) (Math.random() * 10); String newProblem = Integer.toString(a) + "+" + Integer.toString(b); problem.setText(newProblem.toString()); answerBox.setText(""); } }); 

再一次,谢谢。

来自LogCat的东西:

 10-30 04:04:10.490: ERROR/AndroidRuntime(551): FATAL EXCEPTION: main 10-30 04:04:10.490: ERROR/AndroidRuntime(551): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.benhsu.Addition/com.benhsu.Addition.AdditionActivity}: java.lang.ClassCastException: android.widget.TextView 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at android.os.Handler.dispatchMessage(Handler.java:99) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at android.os.Looper.loop(Looper.java:123) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at android.app.ActivityThread.main(ActivityThread.java:3683) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at java.lang.reflect.Method.invokeNative(Native Method) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at java.lang.reflect.Method.invoke(Method.java:507) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at dalvik.system.NativeStart.main(Native Method) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): Caused by: java.lang.ClassCastException: android.widget.TextView 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at com.benhsu.Addition.AdditionActivity.onCreate(AdditionActivity.java:24) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 10-30 04:04:10.490: ERROR/AndroidRuntime(551): ... 11 more 

XML布局文件:

 <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" android:weightSum="1"> <TextView android:layout_width="fill_parent" android:id="@+id/problem" android:layout_height="wrap_content" android:text="@string/problemString"/> <EditText android:layout_height="wrap_content" android:layout_width="match_parent" android:id="@+id/answerBox"> <requestFocus></requestFocus> </EditText> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="@string/status" android:id="@+id/status"></TextView> <Button android:text="Button" android:layout_height="wrap_content" android:id="@+id/button" android:layout_width="wrap_content"></Button> <RelativeLayout android:id="@+id/relativeLayout1" android:layout_height="wrap_content" android:layout_width="match_parent" android:layout_weight="0.14"> <TextView android:layout_width="wrap_content" android:layout_alignParentLeft="true" android:layout_height="wrap_content" android:layout_alignBottom="@+id/textView1" android:text="@string/score" android:id="@+id/textView2" android:textAppearance="?android:attr/textAppearanceLarge" android:layout_alignBaseline="@+id/textView1"></TextView> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/numerator" android:textAppearance="?android:attr/textAppearanceLarge" android:layout_alignParentTop="true" android:layout_toRightOf="@+id/textView2" android:layout_marginLeft="18dp" android:text="@string/numerator"></TextView> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/fraction" android:id="@+id/fraction" android:textAppearance="?android:attr/textAppearanceLarge" android:layout_alignParentTop="true" android:layout_toRightOf="@+id/numerator" android:layout_marginLeft="14dp"></TextView> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/denominator" android:id="@+id/denominator" android:textAppearance="?android:attr/textAppearanceLarge" android:layout_alignParentTop="true" android:layout_toRightOf="@+id/fraction" android:layout_marginLeft="19dp"></TextView> </RelativeLayout> </LinearLayout> 

Solutions Collecting From Web of "java.lang.ClassCastException:android.widget.TextView。 为什么我得到这个?"