Question

我是Android开发的新手，我无法理解这个错误，我正在制作一个简单的秒表应用程序，它有一个Chronometer和3个按钮（启动，停止，重置）我在主java文件中正确定义了所有这些用正确的标签。

它很奇怪，因为我之前测试了应用程序，我的应用程序工作正常，但随后我重新定位了GUI中的按钮，现在它说我没有正确地投射计时器。

06-06 19:11:07.488: E/AndroidRuntime(21511): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.shitstopwatch/com.example.shitstopwatch.ShittyClockActivity}: java.lang.ClassCastException: android.widget.Button cannot be cast to android.widget.Chronometer

这是主要的java文件：

public class ShittyClockActivity extends ActionBarActivity {


Button Start;
Button Stop;
Button Reset;

Chronometer mainChronometer;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_shitty_clock);

    mainChronometer = (Chronometer) this.findViewById(R.id.mainChronometer);

    Start = (Button) this.findViewById(R.id.startButton);
    Stop = (Button) this.findViewById(R.id.stopButton);
    Reset = (Button) this.findViewById(R.id.resetButton);



    addButtonListeners();

}

private void addButtonListeners()
{
    Start.setOnClickListener(new OnClickListener(){

        @Override
        public void onClick(View arg0) {

            int stoppedMilliseconds = 0;
            mainChronometer.setBase(SystemClock.elapsedRealtime() - stoppedMilliseconds);

            mainChronometer.start();
        }

    });

    Stop.setOnClickListener(new OnClickListener(){

        @Override
        public void onClick(View v) {
            mainChronometer.stop();

        }

    });

    Reset.setOnClickListener(new OnClickListener(){

        @Override
        public void onClick(View v) {
            mainChronometer.setBase(SystemClock.elapsedRealtime());


        }

    });


}

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.shitty_clock, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}public class ShittyClockActivity extends ActionBarActivity {


Button Start;
Button Stop;
Button Reset;

Chronometer mainChronometer;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_shitty_clock);

    mainChronometer = (Chronometer) this.findViewById(R.id.mainChronometer);

    Start = (Button) this.findViewById(R.id.startButton);
    Stop = (Button) this.findViewById(R.id.stopButton);
    Reset = (Button) this.findViewById(R.id.resetButton);



    addButtonListeners();

}

private void addButtonListeners()
{
    Start.setOnClickListener(new OnClickListener(){

        @Override
        public void onClick(View arg0) {

            int stoppedMilliseconds = 0;
            mainChronometer.setBase(SystemClock.elapsedRealtime() - stoppedMilliseconds);

            mainChronometer.start();
        }

    });

    Stop.setOnClickListener(new OnClickListener(){

        @Override
        public void onClick(View v) {
            mainChronometer.stop();

        }

    });

    Reset.setOnClickListener(new OnClickListener(){

        @Override
        public void onClick(View v) {
            mainChronometer.setBase(SystemClock.elapsedRealtime());


        }

    });


}

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.shitty_clock, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

以下是带有ID标记的活动XML：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.shitstopwatch.ShittyClockActivity$PlaceholderFragment" >

<Chronometer
    android:id="@+id/mainChronometer"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="34dp"
    android:text="@string/chronometer"
    android:textSize="@dimen/BigText" />

<Button
    android:id="@+id/startButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/mainChronometer"
    android:layout_below="@+id/mainChronometer"
    android:layout_marginTop="63dp"
    android:text="@string/startButton" />

<Button
    android:id="@+id/resetButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/startButton"
    android:layout_below="@+id/startButton"
    android:layout_marginTop="16dp"
    android:text="@string/resetButton" />

<Button
    android:id="@+id/stopButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/resetButton"
    android:layout_below="@+id/resetButton"
    android:layout_marginTop="20dp"
    android:text="@string/stopButton" />

</RelativeLayout>

Answer 1

清理项目（例如，项目＆gt;在Eclipse中清理）。

有时，R常量与APK文件中的资源条目不同步，导致此错误。

当我正确投射时，Android类投射异常错误？

1 个答案: