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安卓工作室 “Attempt to invoke virtual method on a null object reference”

转载 作者:行者123 更新时间:2023-11-29 14:46:28 27 4
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我无法克服这个“尝试在空对象引用上调用虚拟方法”错误。

因此,我在下面代码中的 Button 打开一个带有 EditTextCustomDialog,用户可以在其中更新他的电子邮件地址。

        btnChangeEmail=(Button)findViewById(R.id.buttonChangeEmail);
btnChangeEmail.setOnClickListener(new OnClickListener() {
@Override

//Change Email Dialog
public void onClick (View arg0){
final Dialog dialog = new Dialog(context);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.email_dialog);
//dialog.setCancelable(false);
dialog.setCanceledOnTouchOutside(false);

Button dialogButton = (Button) dialog.findViewById(R.id.buttonSave);
dialogButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText txtNewEmail = (EditText)findViewById(R.id.editTextNewEmail);
AlertDialog.Builder alert = new AlertDialog.Builder(context);
alert.setTitle("Are you sure?");
alert.setMessage("Use " + txtNewEmail.getText().toString() + " as your new address?");
alert.setCancelable(false);
alert.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {

}
});
alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {

dialog.dismiss();
}
});
AlertDialog alertDialog = alert.create();
alertDialog.show();
}
});

Button exitButton = (Button) dialog.findViewById(R.id.buttonExit);
exitButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dialog.dismiss();
}
});

dialog.show();
Window window = dialog.getWindow();
float h = (float) (getResources().getDisplayMetrics().heightPixels * .9);
float w = (float) (getResources().getDisplayMetrics().widthPixels);
int height = (int) h;
int width = (int) w;
window.setLayout(width, height);
}
}

通过单击上述自定义对话框中的保存按钮,它会打开一个警报,提示用户是否真的想继续并覆盖他注册的电子邮件地址。我清楚地实例化了 txtNewEmail 但总是在它说的行上得到空对象引用错误

alert.setMessage("使用 "+ txtNewEmail.getText().toString() + "作为你的新地址?");

感谢任何帮助。谢谢。

这是我的完整 logcat 错误...

03-05 01:51:57.704 4512-4512/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.twenty, PID: 4512
java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference
at com.example.twenty.SettingsActivity$4$1.onClick(SettingsActivity.java:193)
at android.view.View.performClick(View.java:5198)
at android.view.View$PerformClick.run(View.java:21147)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

最佳答案

您在 onClickListener 中的 edittext 也将使用对话框来查找这样的 id

EditText txtNewEmail = (EditText)dialog.findViewById(R.id.editTextNewEmail);

关于安卓工作室 “Attempt to invoke virtual method on a null object reference”,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/35802386/

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