constant expression required when trying to create a switch case block

Question

`an error keeps saying "constant expression required" preventing me from running the app on a device to further develop the app.

am trying to create a sort of google pay.. so i need the selected amounts. but am getting an error saying "constant expression required".. the variable is declared private and not final so i dont know why am getting this error. the value is not even highlighted showing that it is being used. how can i solve this error. i tried innitialising the variable to zero but it still does not help.. `


package com.example.greenearth;

import android.media.Image;
import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.RelativeLayout;
import android.widget.Toast;


public class Donations extends Fragment {

    RadioGroup radioGroup;
    RadioButton minimum;
    RadioButton average;
    RadioButton maximum;
    private int google_amount=0;

    RelativeLayout rl;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_donations, container, false);

    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        radioGroup=view.findViewById(R.id.select);
        minimum=view.findViewById(R.id.fifty);
        average=view.findViewById(R.id.five_hundred);
        maximum=view.findViewById(R.id.ten_thousand);
        rl=view.findViewById(R.id.donater);

        radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                switch (checkedId){
                    case R.id.fifty:
                        google_amount=50;
                        break;

                    case R.id.five_hundred:
                        google_amount=500;
                        break;

                    case R.id.ten_thousand:
                        google_amount=10000;
                        break;
                }
            }
        });

        rl.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if (google_amount>0) {
                    //googlepay
                } else {
                    Toast.makeText(getContext(),"Please choose an amount", Toast.LENGTH_SHORT).show();
                }
            }
        });

    }
}

your problem seems to be that in lines like this: case R.id.fifty: -> the R.id.fifty is not a compile time constant — Stultuske, Jun 08 '23 at 10:05
@Stultuske all the id's i reference in each case give the error — Kaylin Heru, Jun 08 '23 at 12:04
yes, meaning that my previous comment applies to all of them. — Stultuske, Jun 08 '23 at 12:05

Till - Appviewer.io · Answer 1 · 2023-07-27T17:24:59.233

Starting with Android Gradle Plugin 8.0.0, by default, your resources (e.g. R.id. ...) are no longer declared final (i.e. constant expressions) for optimized build speed, which is a prerequisite to be used in switch statements: https://developer.android.com/build/optimize-your-build#use-non-constant-r-classes

If you want to keep the old behavior, you can add this line in the gradle.properties file:

android.nonFinalResIds=false

If you want to fix it by converting it to if/else statements, Android Studio will help you with

Ctrl + 1 or

Alt + Enter

on the switch keyword.

score 1 · Answer 2 · answered Jun 10 '23 at 08:50

Replace your switch statement with if condition like below

 radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(RadioGroup group, int checkedId) {

            if (checkedId == R.id.fifty) {
                google_amount = 50;
            } else if (checkedId == R.id.five_hundred) {
                google_amount = 500;
            } else if (checkedId == R.id.ten_thousand) {
                google_amount = 10000;
            }
        }
    });

If you encounter the "constant expression required" error, ensure that the expression used in the switch statement is indeed a constant expression. If you need to evaluate a non-constant expression, you might consider using if-else statements instead.

score 0 · Answer 3 · answered Aug 17 '23 at 23:07

0

Put this line

android.nonFinalResIds=false

In this file and sync

gradle.properties

That's works for me

answered Aug 17 '23 at 23:07

Roel Leal

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constant expression required when trying to create a switch case block

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