Question

我是Android开发的新手。我创建了一个简单的应用程序，使用eclipse添加两个数字。它工作正常。但是当我在更改按钮和textViews的位置后运行应用程序时，使用图形布局而不直接编辑xml文件，＆＃34;不幸的是应用程序停止了＆＃34;模拟器中显示错误。这种情况几次发生在我身上。请有人知道为什么会这样吗？

logcat的

06-10 16:51:36.690: E/Trace(1343): error opening trace file: No such file or directory (2)
06-10 16:51:36.886: D/AndroidRuntime(1343): Shutting down VM
06-10 16:51:36.886: W/dalvikvm(1343): threadid=1: thread exiting with uncaught exception (group=0xa624b288)
06-10 16:51:36.890: E/AndroidRuntime(1343): FATAL EXCEPTION: main
06-10 16:51:36.890: E/AndroidRuntime(1343): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.a/com.example.a.MainActivity}: java.lang.ClassCastException: android.widget.RadioGroup cannot be cast to android.widget.Button
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread.access$600(ActivityThread.java:130)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.os.Looper.loop(Looper.java:137)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread.main(ActivityThread.java:4745)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at java.lang.reflect.Method.invokeNative(Native Method)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at java.lang.reflect.Method.invoke(Method.java:511)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at dalvik.system.NativeStart.main(Native Method)
06-10 16:51:36.890: E/AndroidRuntime(1343): Caused by: java.lang.ClassCastException: android.widget.RadioGroup cannot be cast to android.widget.Button
06-10 16:51:36.890: E/AndroidRuntime(1343):     at com.example.a.MainActivity$PlaceholderFragment.onCreateView(MainActivity.java:75)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:570)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1163)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.Activity.performStart(Activity.java:5018)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2032)
06-10 16:51:36.890: E/AndroidRuntime(1343):     ... 11 more

fagment_main.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:gravity="fill"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:background="#EB7474"
tools:context="com.example.a.MainActivity$PlaceholderFragment" >

<EditText
    android:id="@+id/n1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:layout_marginLeft="23dp"
    android:layout_marginTop="119dp"
    android:ems="10"
    android:background="#FFE9E9"
    android:hint="num2" >

    <requestFocus />
</EditText>

<EditText
    android:id="@+id/n2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/n1"
    android:layout_alignBottom="@+id/n1"
    android:layout_alignParentRight="true"
    android:layout_marginRight="20dp"
    android:ems="10"
    android:background="#FFE9E9"
    android:hint="num2" />

<Button
    android:id="@+id/b1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/radioGroup1"
    android:layout_marginTop="99dp"
    android:layout_toRightOf="@+id/n1"
    android:text="Answer" />

<TextView
    android:id="@+id/tv1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/b1"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="69dp"
    android:background="#FFE9E9"
    android:text="@string/hello_world" />

<RadioGroup
    android:id="@+id/radioGroup1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/n1"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="132dp"
    android:orientation="horizontal" >

    <RadioButton
        android:id="@+id/r0"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="true"
        android:text="+" />

    <RadioButton
        android:id="@+id/r1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="-" />

    <RadioButton
        android:id="@+id/r2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="X" />

    <RadioButton
        android:id="@+id/r3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="/" />
</RadioGroup>

</RelativeLayout>

activity_main.xml中

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.a.MainActivity"
tools:ignore="MergeRootFrame" />

mainActivity.java

package com.example.a;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.TextView;
import android.os.Build;

public class MainActivity extends ActionBarActivity {

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

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment())
                .commit();
    }
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {

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

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {


    Button A;
    TextView B;
    EditText n1;
    EditText n2;
    RadioGroup radioButtonGroup;

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);



        A = (Button) rootView.findViewById(R.id.b1);
        B = (TextView) rootView.findViewById(R.id.tv1);
        n1 = (EditText) rootView.findViewById(R.id.n1);
        n2 = (EditText) rootView.findViewById(R.id.n2);
        radioButtonGroup = (RadioGroup) rootView.findViewById(R.id.radioGroup1);

        A.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub


                int radioButtonID = radioButtonGroup.getCheckedRadioButtonId();
                View radioButton = radioButtonGroup.findViewById(radioButtonID);
                int idx = radioButtonGroup.indexOfChild(radioButton);

                int num1 = Integer.parseInt(n1.getText().toString());
                int num2 = Integer.parseInt(n2.getText().toString());
                int total = 0;
                switch (idx)
                {
                case 0:
                    total = num1+num2;
                    break;

                case 1:
                    total = num1-num2;
                    break;

                case 2:
                    total = num1*num2;
                    break;

                case 3:
                    total = num1/num2;
                    break;

                case -1:
                    break;
                }

                String ttl = String.valueOf(total);
                B.setText(ttl);

            }
        });



        return rootView;
    }
}

}

Answer 1

当我所做的一切都是在xml布局中交换视图时，我通常会遇到此错误。这是一个ecllipse错误（有时），因此您的资源不会与adt构建器同步。当我得到他的错误时，我做的第一件事就是关闭ecllipse，从任务管理器（windows）结束处理adb.exe，然后再次启动ecllipse。如果这对Android工具没有帮助 - ＆gt;修复项目属性和项目 - ＆gt;清洁。

Answer 2

android.widget.RadioGroup cannot be cast to android.widget.Button

您的XML包含RadioGroup项目
您的Fragment类正在使用findViewById获取该项，并尝试将其强制转换为Button。比如那样：

Button btn = (Button) getView().findViewById(r.id.myRadioButton);

您需要更改XML以使元素或更改您的片段以获取RadioGroup变量：

RadioGroup grp = (RadioGroup) getView().findViewById(r.id.myRadioButton);

Answer 3

问题在于您尝试将RadioGroup投射到Button，而您无法做到。这发生在MainActivity。

如果找不到问题，请发布MainActivity的代码。

Answer 4

我怀疑，我没有看到任何无效的施法。我的猜测是您收到此错误，因为已部署的内容与您在IDE中构建的内容之间存在脱节。 R.java可能陈旧。您需要清理（删除bin，gen，lib，obj目录）并重建项目。

这是一个类似的帖子，同样的事情发生了：Android ClassCastException for RadioGroup into RadioButton

通过关闭模拟器并重新启动IDE来解决他们的问题。

Answer 5

这很简单！我曾经遇到过这个。这看起来令人费解并且非常困难。起初令人沮丧，但你唯一需要做的就是帮助eclipse了解一些（或所有）组件的位置和布局已经被修改/改变的事实。而这应该是通过从头开始构建工作空间来实现的。为此，您需要做的就是关闭并重新启动eclipse。那就是。

不幸的是，更改图形布局时应用程序已停止错误

5 个答案: