Cannot Resolve method maketext

问题

UPDATE

When I use this code Toast.makeText(Lesson111.this, rb.getText(), Toast.LENGTH_SHORT).show(); Im recieving the error message saying cannot resolve method maketext. Then I saw this (The method makeText in the type Toast is not applicable for the arguments) I applied the code Toast.makeText(Lesson111.this.getActivity(), rb.getText(), Toast.LENGTH_SHORT).show(); instead of Toast.makeText(Lesson111.this, rb.getText(), Toast.LENGTH_SHORT).show(); . the error somehow went away. However, when I try to run the application and click the Lesson111. Its forcing the application to close. Am I missing something?

package com.android.pet.view;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.View;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;
import android.view.LayoutInflater;
import android.view.ViewGroup;

import com.doepiccoding.navigationdrawer.R;

public class Lesson111 extends Fragment {
    private RadioGroup radioGroup;


    public View onCreateView(LayoutInflater Inflater, ViewGroup container,Bundle savedInstanceState) {
        View rootView = Inflater.inflate(R.layout.twopointthree, null);

    /* Initialize Radio Group and attach click handler */
        radioGroup = (RadioGroup) rootView.findViewById(R.id.radioGroup);
        radioGroup.clearCheck();

    /* Attach CheckedChangeListener to radio group */
        radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                RadioButton rb = (RadioButton) group.findViewById(checkedId);
                if(null!=rb && checkedId > -1){
                    Toast.makeText(Lesson111.this.getActivity(), rb.getText(), Toast.LENGTH_SHORT).show();
                }

            }
        });
        return rootView;
    }

    public void onClear(View v) {
    /* Clears all selected radio buttons to default */
        radioGroup.clearCheck();
    }

    public void onSubmit(View v) {
        RadioButton rb = (RadioButton) radioGroup.findViewById(radioGroup.getCheckedRadioButtonId());
        Toast.makeText(Lesson111.this.getActivity(), rb.getText(), Toast.LENGTH_SHORT).show();
    }
}

Here what shows on the logcat, Im using Bluestacks as an Emulator

03-27 06:04:19.703 7458-7458/? E/AndroidRuntime: FATAL EXCEPTION: main Process: com.doepiccoding.navigationdrawer, PID: 7458 java.lang.NullPointerException at com.android.pet.view.Lesson111.onCreateView(Lesson111.java:22) at android.support.v4.app.Fragment.performCreateView(Fragment.java:1478) at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927) at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104) at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682) at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1460) at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:440) at android.os.Handler.handleCallback(Handler.java:733) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5021) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643) at dalvik.system.NativeStart.main(Native Method)

回答1:

It seems the error come from line 22

radioGroup.clearCheck();

Can you check that the layout twopointthree has a RadioGroup with the id radioGroup

来源：https://stackoverflow.com/questions/36241327/cannot-resolve-method-maketext