0

我的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);

    }

}

当我运行应用程序时，我得到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

据我了解，我没有将 Button 转换为编辑文本。我不确定，为什么我会收到这个错误。

4

2 回答 2

3

这很有趣。

您是否尝试过清理项目并再次尝试？在这种情况下，它通常会有所帮助 - 资源文件 (ID) 出现故障。

于 2013-10-08T02:43:21.730 回答
1

只需清理您的项目并重建它。
这通常发生在您编辑或重构某些 xml 布局文件之后。
自动生成的资源 ID 一团糟。编辑器的 id 变成了 Button 的。

于 2013-10-08T02:41:29.407 回答