更改按钮和textview的顺序会导致我的应用崩溃

Question

我是Android开发的新手,我遇到了这个奇怪的问题.根据我的布局顺序,应用程序可以正常工作,或者只是在打开之前崩溃.

我的java代码:

package com.exmple.helloandroid;

import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
import android.widget.Toast;
import android.view.View;

public class HelloAndroid extends Activity{
/** Called when the activity is first created. */

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

            // According to logcat. Below is the error line
    Button myButton = (Button) findViewById(R.id.button1);
    myButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
                        Toast.makeText(HelloAndroid.this, "ImageButton clicked!", Toast.LENGTH_SHORT).show();
                }
    });
}
}

和布局XML:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/text1" /> 

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/text1" />
</LinearLayout>

字符串XML:

<?xml version="1.0" encoding="utf-8"?>
<resources>

<string name="text1">This is the first text!</string>
<string name="text2">This is the second text!</string>
<string name="app_name">Hello, Android</string>

</resources>

问题:如果我将textview移到按钮上方,程序就会崩溃.我不明白为什么会这样.

所以:我是否迟钝或者问题是什么？

=============================我测试了问题,是的,有问题,这是lgocat

02-02 02:33:00.433: E/AndroidRuntime(2729): FATAL EXCEPTION: main
02-02 02:33:00.433: E/AndroidRuntime(2729): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.my.android.testing/com.my.android.testing.HelloAndroid}: java.lang.ClassCastException: android.widget.TextView
02-02 02:33:00.433: E/AndroidRuntime(2729):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at android.os.Handler.dispatchMessage(Handler.java:99)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at android.os.Looper.loop(Looper.java:130)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at android.app.ActivityThread.main(ActivityThread.java:3683)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at java.lang.reflect.Method.invokeNative(Native Method)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at java.lang.reflect.Method.invoke(Method.java:507)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at dalvik.system.NativeStart.main(Native Method)
02-02 02:33:00.433: E/AndroidRuntime(2729): Caused by: java.lang.ClassCastException: android.widget.TextView
02-02 02:33:00.433: E/AndroidRuntime(2729):     at com.my.android.testing.TestAndActivity.onCreate(HelloAndroid.java:16)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-02 02:33:00.433: E/AndroidRuntime(2729):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
02-02 02:33:00.433: E/AndroidRuntime(2729):     ... 11 more

Answer 1

清理你的项目将解决你的问题.