Java 碎片内的Android按钮导致应用程序崩溃
我是Android开发新手。我试图在我的登录片段类中添加一个按钮,但当前代码导致应用程序在加载时崩溃。不知道有没有人知道为什么Java 碎片内的Android按钮导致应用程序崩溃,java,android,android-fragments,onclick,Java,Android,Android Fragments,Onclick,我是Android开发新手。我试图在我的登录片段类中添加一个按钮,但当前代码导致应用程序在加载时崩溃。不知道有没有人知道为什么 package com.hidden.hidden.ui.login; import android.content.Context; import android.os.Bundle; import android.view.Gravity; import android.view.LayoutInflater; import android.view.View;
package com.hidden.hidden.ui.login;
import android.content.Context;
import android.os.Bundle;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Button;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.ViewModelProvider;
import com.hidden.hidden.R;
import com.hidden.hidden.databinding.FragmentLoginBinding;
public class LoginFragment extends Fragment {
private LoginViewModel homeViewModel;
private FragmentLoginBinding binding;
private WebView webView;
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
homeViewModel =
new ViewModelProvider(this).get(LoginViewModel.class);
binding = FragmentLoginBinding.inflate(inflater, container, false);
View root = binding.getRoot();
webView = (WebView) root.findViewById(R.id.loginWebView);
webView.setWebViewClient(new WebViewClient());
webView.loadUrl("hiddenurl");
WebSettings webSettings = webView.getSettings();
webSettings.setJavaScriptEnabled(true);
Button button = (Button) root.findViewById(R.id.buttontest);
button.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
// do some toast thing
}
});
return root;
}
@Override
public void onDestroyView() {
super.onDestroyView();
binding = null;
}
}
带着错误
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.hidden.hidden, PID: 10145
java.lang.ClassCastException: androidx.constraintlayout.widget.ConstraintLayout cannot be cast to android.widget.Button
at com.hidden.hidden.ui.login.LoginFragment.onCreateView(LoginFragment.java:44)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2698)
at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:320)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1187)
at androidx.fragment.app.FragmentManager.addAddedFragments(FragmentManager.java:2224)
at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1997)
at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1953)
at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1849)
at androidx.fragment.app.FragmentManager.dispatchStateChange(FragmentManager.java:2629)
at androidx.fragment.app.FragmentManager.dispatchActivityCreated(FragmentManager.java:2577)
at androidx.fragment.app.Fragment.performActivityCreated(Fragment.java:2722)
at androidx.fragment.app.FragmentStateManager.activityCreated(FragmentStateManager.java:346)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1188)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1356)
at androidx.fragment.app.FragmentManager.moveFragmentToExpectedState(FragmentManager.java:1434)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1497)
at androidx.fragment.app.FragmentManager.dispatchStateChange(FragmentManager.java:2625)
at androidx.fragment.app.FragmentManager.dispatchActivityCreated(FragmentManager.java:2577)
at androidx.fragment.app.FragmentController.dispatchActivityCreated(FragmentController.java:247)
at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:541)
at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:210)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1435)
at android.app.Activity.performStart(Activity.java:8210)
at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3800)
at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:221)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:201)
at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:173)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2289)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:246)
at android.app.ActivityThread.main(ActivityThread.java:8462)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:596)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)
我的最终目的是在登录后从我的webapi获得回复,并从登录活动到MainActivity
谢谢
尝试删除:
binding = FragmentLoginBinding.inflate(inflater, container, false);
View root = binding.getRoot();
webView = (WebView) root.findViewById(R.id.loginWebView);
webView.setWebViewClient(new WebViewClient());
webView.loadUrl("hiddenurl");
WebSettings webSettings = webView.getSettings();
webSettings.setJavaScriptEnabled(true);
Button button = (Button) root.findViewById(R.id.buttontest);
button.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
// do some toast thing
}
});
return root;
发件人:
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
homeViewModel =
new ViewModelProvider(this).get(LoginViewModel.class);
}
尝试添加:
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
binding = FragmentLoginBinding.inflate(inflater, container, false);
View root = binding.getRoot();
webView = (WebView) root.findViewById(R.id.loginWebView);
webView.setWebViewClient(new WebViewClient());
webView.loadUrl("hiddenurl");
WebSettings webSettings = webView.getSettings();
webSettings.setJavaScriptEnabled(true);
Button button = (Button) root.findViewById(R.id.buttontest);
button.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
// do some toast thing
}
});
return root;
}
希望这有帮助……
请告知它是否工作请尝试删除:
binding = FragmentLoginBinding.inflate(inflater, container, false);
View root = binding.getRoot();
webView = (WebView) root.findViewById(R.id.loginWebView);
webView.setWebViewClient(new WebViewClient());
webView.loadUrl("hiddenurl");
WebSettings webSettings = webView.getSettings();
webSettings.setJavaScriptEnabled(true);
Button button = (Button) root.findViewById(R.id.buttontest);
button.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
// do some toast thing
}
});
return root;
发件人:
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
homeViewModel =
new ViewModelProvider(this).get(LoginViewModel.class);
}
尝试添加:
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
binding = FragmentLoginBinding.inflate(inflater, container, false);
View root = binding.getRoot();
webView = (WebView) root.findViewById(R.id.loginWebView);
webView.setWebViewClient(new WebViewClient());
webView.loadUrl("hiddenurl");
WebSettings webSettings = webView.getSettings();
webSettings.setJavaScriptEnabled(true);
Button button = (Button) root.findViewById(R.id.buttontest);
button.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
// do some toast thing
}
});
return root;
}
希望这有帮助……
请告诉它是否工作id
buttontest
分配给您的constraintlayout,而不是按钮。只是一个简单的打字错误。例外情况也很清楚地表明了这一点。
替换
与
id
buttontest
分配给您的constraintlayout,而不是按钮。只是一个简单的打字错误。例外情况也很清楚地表明了这一点。
替换
与
内部OnCreateView:
return inflater.inflate(R.layout.login_fragment, container, false);
尝试删除:
binding = FragmentLoginBinding.inflate(inflater, container, false);
View root = binding.getRoot();
希望这有助于现在。。。
多谢各位
请让我知道它是否工作。OnCreateView内部:
return inflater.inflate(R.layout.login_fragment, container, false);
尝试删除:
binding = FragmentLoginBinding.inflate(inflater, container, false);
View root = binding.getRoot();
希望这有助于现在。。。
多谢各位
请让我知道它是否有效。谢谢您的回复。我已经尝试了你所说的,我没有得到错误的充气机和容器的红色,如上图所示。错误是无法解析符号“容器”,无法解析符号“充气机”,谢谢您的回复。我已经尝试了你所说的,我没有得到错误的充气机和容器的红色,如上图所示。错误是无法解析符号“container”,无法解析符号“inflater”您是否可以添加登录片段XML文件的代码我已添加登录片段XML您是否可以添加登录片段XML文件的代码我已添加登录片段XML