에러메시지----------- E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.project, PID: 29100 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.project/com.example.project.CustomCalendarActivity}: android.view.InflateException: Binary XML file line #9 in com.example.project:layout/calendar_layout_activity: Binary XML file line #9 in com.example.project:layout/calendar_layout_activity: Error inflating class com.example.project.CustomCalendarView at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:214) at android.app.ActivityThread.main(ActivityThread.java:7356) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) Caused by: android.view.InflateException: Binary XML file line #9 in com.example.project:layout/calendar_layout_activity: Binary XML file line #9 in com.example.project:layout/calendar_layout_activity: Error inflating class com.example.project.CustomCalendarView Caused by: android.view.InflateException: Binary XML file line #9 in com.example.project:layout/calendar_layout_activity: Error inflating class com.example.project.CustomCalendarView Caused by: java.lang.reflect.InvocationTargetException at java.lang.reflect.Constructor.newInstance0(Native Method) at java.lang.reflect.Constructor.newInstance(Constructor.java:343) at android.view.LayoutInflater.createView(LayoutInflater.java:854) at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:1006) at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:961) at android.view.LayoutInflater.rInflate(LayoutInflater.java:1123) at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084) at android.view.LayoutInflater.inflate(LayoutInflater.java:682) at android.view.LayoutInflater.inflate(LayoutInflater.java:534) at android.view.LayoutInflater.inflate(LayoutInflater.java:481) at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:555) at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:161) at com.example.project.CustomCalendarActivity.onCreate(CustomCalendarActivity.java:15) at android.app.Activity.performCreate(Activity.java:7802) at android.app.Activity.performCreate(Activity.java:7791) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1299) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:214) at android.app.ActivityThread.main(ActivityThread.java:7356) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) E/AndroidRuntime: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference at com.example.project.CustomCalendarView.SetUpCalendar(CustomCalendarView.java:149) at com.example.project.CustomCalendarView.(CustomCalendarView.java:56) ... 28 more I/Process: Sending signal. PID: 29100 SIG: 9

Process 29100 terminated.

자바코드

package com.example.project;

import android.app.Activity; import android.os.Bundle;

import androidx.annotation.Nullable; import androidx.appcompat.app.AppCompatActivity;

public class CustomCalendarActivity extends AppCompatActivity { CustomCalendarView customCalendarView;

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.calendar_layout_activity);

    customCalendarView=(CustomCalendarView)findViewById(R.id.custom_calendar_view);
}

}

xml파일

<?xml version="1.0" encoding="utf-8"?>

<com.example.project.CustomCalendarView
    android:id="@+id/custom_calendar_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.0"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.0"></com.example.project.CustomCalendarView>