java.lang.ClassCastException：android.support.v7.widget.AppCompatButton无法转换为android.support.design.widget.FloatingActionButton

Question

It is not a clean and rebuild issue AT ALL! Make module will not resolve this issue either. This is the only FlotingActionButton I'm using in my code. One solution said this only occurs with an anchor parameter but as you can see I am not using one so I dont know what to make of it.

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

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/coverpic"
    tools:context="com.android.nohiccupsbeta.MainActivity">

    <android.support.design.widget.CoordinatorLayout
        android:id="@+id/effects_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <android.support.design.widget.FloatingActionButton
            android:id="@+id/fab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_alignParentEnd="true"
            android:layout_alignParentRight="true"
            android:layout_gravity="top|end"
            android:layout_marginTop="400dp"
            android:layout_marginRight="15dp"
            android:src="@drawable/ic_book"
            app:backgroundTint="@color/primary_color" />

    </android.support.design.widget.CoordinatorLayout>

    <android.support.design.widget.CoordinatorLayout
        android:id="@+id/take_test"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <android.support.design.widget.FloatingActionButton
            android:id="@+id/fab2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom|end"
            android:layout_margin="@dimen/fab_margin"
            app:backgroundTint="@color/primary_color"
            android:src="@drawable/ic_handcuffs" />

    </android.support.design.widget.CoordinatorLayout>

</RelativeLayout>

This is the JAVA code. I tried importing the Coordinator Layout but that is not possible. I also tried declaring the fab var differently just to get the same error :

    package com.android.nohiccupsbeta;

import android.content.Intent;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;

public class MainActivity extends AppCompatActivity {

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


        FloatingActionButton fab = (FloatingActionButton)findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(MainActivity.this, pageone.class));
            }
        });


        FloatingActionButton fab2 = (FloatingActionButton)findViewById(R.id.fab2);
        fab2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(MainActivity.this, BacTest.class));
            }
        });
    }

}

Answer 1

Your second FloatingActionButton does not have an id, and the one you are trying to cast into a FAB is the CoordinatorLayout.

So, you should set an id in your layout for your fabs like this

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

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/coverpic">

    <android.support.design.widget.CoordinatorLayout
        android:id="@+id/effects_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <android.support.design.widget.FloatingActionButton
            android:id="@+id/fab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_alignParentEnd="true"
            android:layout_alignParentRight="true"
            android:layout_gravity="top|end"
            android:layout_marginTop="400dp"
            android:layout_marginRight="15dp"
            android:src="@drawable/ic_book"
            app:backgroundTint="@color/primary_color" />

    </android.support.design.widget.CoordinatorLayout>

    <android.support.design.widget.CoordinatorLayout
        android:id="@+id/take_test"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <android.support.design.widget.FloatingActionButton
            android:id="@+id/fab2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom|end"
            android:layout_margin="@dimen/fab_margin"
            app:backgroundTint="@color/primary_color"
            android:src="@drawable/ic_handcuffs" />

    </android.support.design.widget.CoordinatorLayout>

</RelativeLayout>

and your fabs to match the new ids like this

FloatingActionButton fab = (FloatingActionButton)findViewById(R.id.fab);
FloatingActionButton fab2 = (FloatingActionButton)findViewById(R.id.fab2);