在按钮的onClick内部，LinearLayout为null

Question

I'm trying to hide a linearlayout on a button click and display another linearlayout which is in the same layout file. But the linearlayouts are null inside the onclick of the button.

The displayLayout and editLayout are null.

        displayLayout = (LinearLayout) findViewById(R.id.linearLayout);
    editLayout = (LinearLayout) findViewById(R.id.editLayout); 
    edit.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            displayLayout = (LinearLayout) findViewById(R.id.linearLayout);
            editLayout = (LinearLayout) findViewById(R.id.editLayout);
            displayLayout.setVisibility(View.GONE); //error occurs here
            editLayout.setVisibility(View.VISIBLE);
        }
    });
}

Here's the layout file:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.prematixsofs.taxiapp.EditUserDetails">

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/ScrollView01"
    android:layout_width="match_parent"
    android:layout_height="fill_parent"

    >
    <!--Display UserDetails Layout-->

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/displayLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:orientation="vertical">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:orientation="vertical"
            android:padding="15dp">

            <TextView
                android:id="@+id/name"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="5dp"
                android:background="@drawable/custom_edittext"
                android:gravity="center"
                android:padding="8dp"
                android:paddingLeft="10dp"
                android:paddingRight="5dp" />

            <TextView
                android:id="@+id/phNo"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="10dp"
                android:background="@drawable/custom_edittext"
                android:gravity="center"
                android:padding="8dp"
                android:paddingLeft="10dp"
                android:paddingRight="5dp" />

            <TextView
                android:id="@+id/email"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="10dp"
                android:background="@drawable/custom_edittext"
                android:gravity="center"
                android:inputType="textEmailAddress"
                android:padding="8dp"
                android:paddingLeft="10dp"
                android:paddingRight="5dp" />

        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:orientation="vertical"
            android:padding="15dp">

            <Button
                android:id="@+id/edit"
                android:layout_width="300dp"
                android:layout_height="wrap_content"
                android:background="@drawable/button_custom"
                android:text="Edit"
                android:textColor="#ffffff" />
        </LinearLayout>

    </LinearLayout>
</ScrollView>

<!--Edit Layout -->
<LinearLayout
    android:id="@+id/editLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"

    >

    <EditText
        android:id="@+id/editName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp"
        android:background="@drawable/custom_edittext"
        android:gravity="center"
        android:padding="8dp"
        android:paddingLeft="10dp"
        android:paddingRight="5dp" />

    <EditText
        android:id="@+id/editPhNo"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:background="@drawable/custom_edittext"
        android:gravity="center"
        android:padding="8dp"
        android:paddingLeft="10dp"
        android:paddingRight="5dp" />

    <EditText
        android:id="@+id/editPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:background="@drawable/custom_edittext"
        android:gravity="center"
        android:padding="8dp"
        android:paddingLeft="10dp"
        android:paddingRight="5dp" />

    <EditText
        android:id="@+id/editConfirmPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:background="@drawable/custom_edittext"
        android:gravity="center"
        android:padding="8dp"
        android:paddingLeft="10dp"
        android:paddingRight="5dp" />

</LinearLayout>

Answer 1

Just fix your view ID in your code

    displayLayout = (LinearLayout) findViewById(R.id.displayLayout);
    editLayout = (LinearLayout) findViewById(R.id.editLayout); 
    edit.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            displayLayout.setVisibility(View.GONE);
            editLayout.setVisibility(View.VISIBLE);
        }
    });
}

Answer 2

error code displayLayout = (LinearLayout) findViewById(R.id.linearLayout);

right code displayLayout = (LinearLayout) findViewById(R.id.displayLayout);

you set a not exist id.