我正在制作一个具有登录注销功能的应用程序。我使用 imagebuton 注销，但在阅读 logcat 报告后登录后崩溃，似乎是图像按钮导致的
这是我的 xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical"
android:background="#0099CC" >
<TextView
android:layout_width="125dp"
android:textColor="#000000"
android:layout_height="40dp"
android:text="First Name"
android:id="@+id/textView3"
android:layout_below="@+id/textView2"
android:layout_alignParentLeft="true"
android:textSize="15dp"/>
<TextView
android:layout_width="200dp"
android:layout_height="40dp"
android:id="@+id/fname"
android:textColor="#000000"
android:layout_alignTop="@+id/textView3"
android:layout_alignParentRight="true"
android:textSize="15dp"/>
<TextView
android:layout_width="125dp"
android:layout_height="40dp"
android:text="Last Name"
android:textColor="#000000"
android:id="@+id/textView5"
android:layout_below="@+id/textView3"
android:textSize="15dp"
android:layout_toLeftOf="@+id/fname"/>
<ImageButton
android:id="@+id/logoutbtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/logout" />
<TextView
android:layout_width="200dp"
android:layout_height="40dp"
android:id="@+id/lname"
android:textColor="#000000"
android:layout_below="@+id/textView3"
android:layout_toRightOf="@+id/textView5"
android:textSize="15dp"/>
<TextView
android:layout_width="125dp"
android:layout_height="40dp"
android:text="E-mail"
android:textColor="#000000"
android:id="@+id/textView7"
android:layout_below="@+id/textView5"
android:layout_toLeftOf="@+id/textView2"
android:textSize="15dp"/>
<TextView
android:layout_width="200dp"
android:layout_height="40dp"
android:id="@+id/email"
android:textColor="#000000"
android:layout_below="@+id/textView5"
android:layout_alignLeft="@+id/fname"
android:textSize="15dp"/>
<TextView
android:layout_width="125dp"
android:layout_height="40dp"
android:text="Username"
android:textColor="#000000"
android:id="@+id/textView9"
android:layout_below="@+id/textView7"
android:textSize="15dp"
android:textIsSelectable="false"/>
<TextView
android:layout_width="200dp"
android:layout_height="40dp"
android:id="@+id/uname"
android:textColor="#000000"
android:layout_below="@+id/email"
android:layout_alignLeft="@+id/email"
android:textSize="15dp"/>
<TextView
android:layout_width="125dp"
android:layout_height="40dp"
android:text="Registered at"
android:id="@+id/textView11"
android:textColor="#000000"
android:layout_below="@+id/textView9"
android:layout_toLeftOf="@+id/uname"
android:textSize="15dp"/>
<TextView
android:layout_width="200dp"
android:layout_height="40dp"
android:id="@+id/regat"
android:textColor="#000000"
android:layout_below="@+id/textView9"
android:layout_alignRight="@+id/lname"
android:textSize="15dp"/>
<Button
android:layout_width="200dp"
android:layout_height="wrap_content"
android:text="Back to Login"
android:id="@+id/login"
android:textColor="#000000"
android:layout_below="@+id/textView11"
android:textSize="13dp"
android:layout_alignRight="@+id/lname"
android:layout_alignParentLeft="true"/>
</LinearLayout>
这是我的主要 Activity
package com.learn2crack.tab;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;
import android.widget.Toast;
import com.learn2crack.library.DatabaseHandler;
import com.learn2crack.tab.Android;
import java.util.HashMap;
public class Android extends Fragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
View android = inflater.inflate(R.layout.android_frag, container, false);
DatabaseHandler db = new DatabaseHandler(getActivity());
HashMap<String,String> user = new HashMap<String, String>();
user = db.getUserDetails();
/**
* Displays the registration details in Text view
**/
final ImageButton logoutbtn = (ImageButton)android.findViewById(R.id.logoutbtn);
final TextView fname = (TextView)android.findViewById(R.id.fname);
final TextView lname = (TextView)android.findViewById(R.id.lname);
final TextView uname = (TextView)android.findViewById(R.id.uname);
final TextView email = (TextView)android.findViewById(R.id.email);
final TextView created_at = (TextView)android.findViewById(R.id.regat);
fname.setText(user.get("fname"));
lname.setText(user.get("lname"));
uname.setText(user.get("uname"));
email.setText(user.get("email"));
created_at.setText(user.get("created_at"));
logoutbtn.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
logout();
}
});
return android;}
public void logout(){
AlertDialog.Builder alertDialog = new AlertDialog.Builder(Android.this.getActivity());
alertDialog.setTitle("Logout"); // Sets title for your alertbox
alertDialog.setMessage("Are you sure you want to Logout ?"); // Message to be displayed on alertbox
/* When positive (yes/ok) is clicked */
alertDialog.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int which) {
Intent login = new Intent(getActivity(), Login.class);
login.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(login);
// Closing dashboard screen
getActivity().finish();
}
});
/* When negative (No/cancel) button is clicked*/
alertDialog.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
alertDialog.show();
}
}
Logcat 报告
09-16 12:02:21.529: E/AndroidRuntime(1469): FATAL EXCEPTION: main
09-16 12:02:21.529: E/AndroidRuntime(1469): Process: com.learn2crack.tab, PID: 1469
09-16 12:02:21.529: E/AndroidRuntime(1469): java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.ImageButton
09-16 12:02:21.529: E/AndroidRuntime(1469): at com.learn2crack.tab.Android.onCreateView(Android.java:46)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:163)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.support.v4.view.ViewPager.populate(ViewPager.java:1068)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.View.measure(View.java:16497)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.View.measure(View.java:16497)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
09-16 12:02:21.529: E/AndroidRuntime(1469): at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:327)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.View.measure(View.java:16497)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
09-16 12:02:21.529: E/AndroidRuntime(1469): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.View.measure(View.java:16497)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1916)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1113)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1295)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5670)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.Choreographer.doCallbacks(Choreographer.java:574)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.Choreographer.doFrame(Choreographer.java:544)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.os.Handler.handleCallback(Handler.java:733)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.os.Handler.dispatchMessage(Handler.java:95)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.os.Looper.loop(Looper.java:136)
09-16 12:02:21.529: E/AndroidRuntime(1469): at android.app.ActivityThread.main(ActivityThread.java:5017)
09-16 12:02:21.529: E/AndroidRuntime(1469): at java.lang.reflect.Method.invokeNative(Native Method)
09-16 12:02:21.529: E/AndroidRuntime(1469): at java.lang.reflect.Method.invoke(Method.java:515)
09-16 12:02:21.529: E/AndroidRuntime(1469): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
09-16 12:02:21.529: E/AndroidRuntime(1469): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
09-16 12:02:21.529: E/AndroidRuntime(1469): at dalvik.system.NativeStart.main(Native Method)
最佳答案
您需要显示com.learn2crack.tab.Android.onCreateView但最有可能的是，您正在做类似 ImageButton img = (ImageButton) findViewById(<some_textview_id>) 的事情。确保您使用正确的 ID ( logoutbtn )。
关于java - 图像按钮导致崩溃，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/25875195/