機器人ClassCastException異常錯誤 「按鈕無法施展作爲的EditText」

Question

我Activity_main.xml

<Button 
    android:id="@+id/MyButton" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignParentBottom="true" 
    android:layout_alignParentRight="true" 
    android:text="@string/button" /> 

<EditText 
    android:id="@+id/PasswordText" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:ems="10" 
    android:hint="@string/PasswordText" 
    android:inputType="textPassword" /> 

<EditText 
    android:id="@+id/UsernameText" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignParentLeft="true" 
    android:layout_alignParentTop="true" 
    android:ems="10" 
    android:hint="@string/UsernameText" > 

    <requestFocus /> 
</EditText> 

Java文件MainAcivity.java

package com.example.buttonclicktutorial; 

import android.os.Bundle; 
import android.app.Activity; 
import android.content.Intent; 
import android.view.Menu; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.EditText; 

public class MainActivity extends Activity implements OnClickListener{ 
    EditText name; 
    EditText pass; 
    Button login; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     name = (EditText) findViewById(R.id.UsernameText); 
     pass = (EditText) findViewById(R.id.PasswordText); 
     login = (Button) findViewById(R.id.MyButton); 
     login.setOnClickListener(this); 
    } 

    @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 void onClick(View v) { 
     // TODO Auto-generated method stub 
     Intent myIntent = new Intent(MainActivity.this, 
       NewActivity.class); 
     startActivity(myIntent); 

    } 

} 

當我運行應用程序，我正在得到ClassCastException

10-08 13:28:11.970: E/AndroidRuntime(6674): FATAL EXCEPTION: main 
10-08 13:28:11.970: E/AndroidRuntime(6674): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.buttonclicktutorial/com.example.buttonclicktutorial.MainActivity}: java.lang.ClassCastException: android.widget.Button cannot be cast to android.widget.EditText 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1978) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2003) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at android.app.ActivityThread.access$600(ActivityThread.java:123) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1169) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at android.os.Handler.dispatchMessage(Handler.java:99) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at android.os.Looper.loop(Looper.java:137) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at android.app.ActivityThread.main(ActivityThread.java:4446) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at java.lang.reflect.Method.invokeNative(Native Method) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at java.lang.reflect.Method.invoke(Method.java:511) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at dalvik.system.NativeStart.main(Native Method) 
10-08 13:28:11.970: E/AndroidRuntime(6674): Caused by: java.lang.ClassCastException: android.widget.Button cannot be cast to android.widget.EditText 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at com.example.buttonclicktutorial.MainActivity.onCreate(MainActivity.java:20) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at android.app.Activity.performCreate(Activity.java:4465) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1942) 
10-08 13:28:11.970: E/AndroidRuntime(6674):  ... 11 more 

據我所知，我沒有將Button作爲edittext。我不確定，爲什麼我得到這個錯誤。

Answer 1

這是一個有趣的。

您是否嘗試過清潔項目並重試？在這種情況下它通常會有所幫助 - 資源文件（ID）無法正常工作。

Answer 2

只需清理您的項目並重建它。
這經常發生在您編輯或重構一些xml佈局文件之後。
自動生成的資源ID很混亂。編輯器的ID變成了Button的。