为什么我得到这个窗口管理器$坏令牌异常:无法添加窗口 - 令牌空不适用于应用程序

Question

我正在研究一种让用户在我的应用程序中输入用户名的方法，但是我遇到了这个异常。这是我的代码：

package myPackage;
public class MainActivity extends AppCompatActivity {
    private Context myAppContext;
    private String username;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myAppContext = getApplicationContext();
        // Username Input Dialog
        final EditText userInput = new EditText(this);
        final SharedPreferences myAppPreferences = getSharedPreferences(Constants.PREFS_NAME, MODE_PRIVATE);
        final TextView usernameTextview = (TextView)findViewById(R.id.username_box);
        username = myAppPreferences.getString("username", null);
        usernameTextview.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(username != null){
                    userInput.setText(username);
                }
                AlertDialog.Builder inputAlert = new AlertDialog.Builder(myAppContext);
                inputAlert.setIcon(R.drawable.alert_50x50);
                inputAlert.setTitle("Username");
                inputAlert.setMessage("Please enter your username.");
                inputAlert.setView(userInput);
                inputAlert.setPositiveButton("Submit", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        SimpleDateFormat sdf = new SimpleDateFormat(Constants.STANDARD_FILE_TIMESTAMP, Locale.US);
                        username = (!userInput.getText().toString().equalsIgnoreCase("")) ? userInput.getText().toString() : Constants.TABLET_ID;
                        SharedPreferences.Editor editor = myAppPreferences.edit();
                        editor.putString("username", username);
                        editor.putString("log-in date", sdf.format(new Date()));
                        editor.apply();
                        usernameTextview.append(username);
                    }
                });
                inputAlert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        usernameTextview.append(username);
                        dialog.dismiss();
                    }
                });
                AlertDialog alertDialog = inputAlert.create();
                // THE FOLLOWING LINE IS WHERE I GET MY WindowManager$BadTokenException
                alertDialog.show();
            }
        });
        if(username != null){
            usernameTextview.append(username);
        } else {
            AlertDialog.Builder inputAlert = new AlertDialog.Builder(this);
            inputAlert.setIcon(R.drawable.alert_50x50);
            inputAlert.setTitle("Username");
            inputAlert.setMessage("Please enter your username.");
            inputAlert.setView(userInput);
            inputAlert.setPositiveButton("Submit", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    SimpleDateFormat sdf = new SimpleDateFormat(Constants.STANDARD_FILE_TIMESTAMP, Locale.US);
                    username = (!userInput.getText().toString().equalsIgnoreCase("")) ? userInput.getText().toString() : Constants.TABLET_ID;
                    SharedPreferences.Editor editor = myAppPreferences.edit();
                    editor.putString("username", username);
                    editor.putString("log-in date", sdf.format(new Date()));
                    editor.apply();
                    usernameTextview.append(username);
                }
            });
            inputAlert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    usernameTextview.append(username);
                    dialog.dismiss();
                }
            });
            AlertDialog alertDialog = inputAlert.create();
            alertDialog.show();
        }
    }
}

我已经标记了我得到异常的行。

编辑：

这是我从以下位置更改代码后遇到的新错误

AlertDialog.Builder inputAlert = new AlertDialog.Builder(this);

自

AlertDialog.Builder inputAlert = new AlertDialog.Builder(MainActivity.this);

我还把这个声明移到了声明之后：

final TextView usernameTextview = (TextView)findViewById(R.id.username_box);

我删除了代码中的重复项。

日志猫：

W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x40a7c1f8)
E/AndroidRuntime: FATAL EXCEPTION: main
E/AndroidRuntime: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
E/AndroidRuntime:     at android.view.ViewGroup.addViewInner(ViewGroup.java:3337)
E/AndroidRuntime:     at android.view.ViewGroup.addView(ViewGroup.java:3208)
E/AndroidRuntime:     at android.view.ViewGroup.addView(ViewGroup.java:3188)
E/AndroidRuntime:     at com.android.internal.app.AlertController.setupView(AlertController.java:401)
E/AndroidRuntime:     at com.android.internal.app.AlertController.installContent(AlertController.java:241)
E/AndroidRuntime:     at android.app.AlertDialog.onCreate(AlertDialog.java:336)
E/AndroidRuntime:     at android.app.Dialog.dispatchOnCreate(Dialog.java:353)
E/AndroidRuntime:     at android.app.Dialog.show(Dialog.java:257)
E/AndroidRuntime:     at myPackage.main.MainActivity$2.onClick(MainActivity.java:138)
E/AndroidRuntime:     at android.view.View.performClick(View.java:3511)
E/AndroidRuntime:     at android.view.View$PerformClick.run(View.java:14105)
E/AndroidRuntime:     at android.os.Handler.handleCallback(Handler.java:605)
E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:4424)
E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method)

Answer 1

创建AlertDialog时使用Activity context

AlertDialog.Builder inputAlert = new AlertDialog.Builder(yourActivity.this);

Answer 2

我想

发布我问题的最终解决方案。感谢用户 M D，我能够解决我原来的问题。经过一些谷歌搜索，我能够解决我随后的问题

"非法状态例外：指定的子项已有父项。您必须先在孩子的父级上调用 removeView（） "

我通过移动 EditText 声明来做到这一点。

package myPackage;
public class MainActivity extends AppCompatActivity {
    private String username;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final SharedPreferences myAppPreferences = getSharedPreferences(Constants.PREFS_NAME, MODE_PRIVATE);
        final TextView usernameTextview = (TextView)findViewById(R.id.username_box);
        username = myAppPreferences.getString("username", null);
        usernameTextview.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                final EditText userInput = new EditText(MainActivity.this);
                if(username != null){
                    userInput.setText(username);
                }
                AlertDialog.Builder inputAlert = new AlertDialog.Builder(MainActivity.this);
                inputAlert.setIcon(R.drawable.alert_50x50);
                inputAlert.setTitle("Username");
                inputAlert.setMessage("Please enter your username.");
                inputAlert.setView(userInput);
                inputAlert.setPositiveButton("Submit", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        SimpleDateFormat sdf = new SimpleDateFormat(Constants.STANDARD_FILE_TIMESTAMP, Locale.US);
                        username = (!userInput.getText().toString().equalsIgnoreCase("")) ? userInput.getText().toString() : Constants.TABLET_ID;
                        SharedPreferences.Editor editor = myAppPreferences.edit();
                        editor.putString("username", username);
                        editor.putString("log-in date", sdf.format(new Date()));
                        editor.apply();
                        usernameTextview.setText(username);
                    }
                });
                inputAlert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        usernameTextview.setText(username);
                        dialog.dismiss();
                    }
                });
                AlertDialog alertDialog = inputAlert.create();
                alertDialog.show();
            }
        });
        if(username != null){
            usernameTextview.setText(username);
        } else {
            final EditText userInput = new EditText(this);
            AlertDialog.Builder inputAlert = new AlertDialog.Builder(MainActivity.this);
            inputAlert.setIcon(R.drawable.alert_50x50);
            inputAlert.setTitle("Username");
            inputAlert.setMessage("Please enter your username.");
            inputAlert.setView(userInput);
            inputAlert.setPositiveButton("Submit", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    SimpleDateFormat sdf = new SimpleDateFormat(Constants.STANDARD_FILE_TIMESTAMP, Locale.US);
                    username = (!userInput.getText().toString().equalsIgnoreCase("")) ? userInput.getText().toString() : Constants.TABLET_ID;
                    SharedPreferences.Editor editor = myAppPreferences.edit();
                    editor.putString("username", username);
                    editor.putString("log-in date", sdf.format(new Date()));
                    editor.apply();
                    usernameTextview.setText(username);
                }
            });
            inputAlert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    usernameTextview.setText(Constants.TABLET_ID);
                    dialog.dismiss();
                }
            });
            AlertDialog alertDialog = inputAlert.create();
            alertDialog.show();
        }
    }
}