谁能解释我的android程序中有什么错误？
日志猫：
07-13 09:04:18.429: D/AndroidRuntime(274): Shutting down VM
07-13 09:04:18.429: W/dalvikvm(274): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
07-13 09:04:18.469: E/AndroidRuntime(274): FATAL EXCEPTION: main
07-13 09:04:18.469: E/AndroidRuntime(274): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.firstapplication1/com.example.firstapplication1.StartingPoint}: java.lang.ClassCastException: android.widget.TextView
07-13 09:04:18.469: E/AndroidRuntime(274): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
07-13 09:04:18.469: E/AndroidRuntime(274): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
07-13 09:04:18.469: E/AndroidRuntime(274): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
07-13 09:04:18.469: E/AndroidRuntime(274): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
07-13 09:04:18.469: E/AndroidRuntime(274): at android.os.Handler.dispatchMessage(Handler.java:99)
07-13 09:04:18.469: E/AndroidRuntime(274): at android.os.Looper.loop(Looper.java:123)
07-13 09:04:18.469: E/AndroidRuntime(274): at android.app.ActivityThread.main(ActivityThread.java:4627)
07-13 09:04:18.469: E/AndroidRuntime(274): at java.lang.reflect.Method.invokeNative(Native Method)
07-13 09:04:18.469: E/AndroidRuntime(274): at java.lang.reflect.Method.invoke(Method.java:521)
07-13 09:04:18.469: E/AndroidRuntime(274): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
07-13 09:04:18.469: E/AndroidRuntime(274): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
07-13 09:04:18.469: E/AndroidRuntime(274): at dalvik.system.NativeStart.main(Native Method)
07-13 09:04:18.469: E/AndroidRuntime(274): Caused by: java.lang.ClassCastException: android.widget.TextView
07-13 09:04:18.469: E/AndroidRuntime(274): at com.example.firstapplication1.StartingPoint.onCreate(StartingPoint.java:25)
07-13 09:04:18.469: E/AndroidRuntime(274): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
07-13 09:04:18.469: E/AndroidRuntime(274): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
07-13 09:04:18.469: E/AndroidRuntime(274): ... 11 more
07-13 09:04:28.659: I/Process(274): Sending signal. PID: 274 SIG: 9
起点.java：
public class StartingPoint extends Activity {
int counter;
Button add;
Button sub;
TextView display;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
counter=0;
add = (Button) findViewById(R.id.bAdd);
sub = (Button) findViewById(R.id.bSub);
display = (Button) findViewById(R.id.tvDisplay);
add.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
counter++;
display.setText("Your Total is " + counter);
}
});
sub.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
counter--;
display.setText("Your Total is " + counter);
}
});
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.starting_point, menu);
return true;
}
}