FATAL EXCEPTION: main 오류질문합니다 ㅠㅠ

Question

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.chayoungyun2, PID: 12817
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.chayoungyun2/com.example.chayoungyun2.calculatorActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2724)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2789)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1527)
        at android.os.Handler.dispatchMessage(Handler.java:110)
        at android.os.Looper.loop(Looper.java:203)
        at android.app.ActivityThread.main(ActivityThread.java:6251)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924)
     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.chayoungyun2.calculatorActivity.onCreate(calculatorActivity.java:46)
        at android.app.Activity.performCreate(Activity.java:6666)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2677)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2789) 
        at android.app.ActivityThread.-wrap12(ActivityThread.java) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1527) 
        at android.os.Handler.dispatchMessage(Handler.java:110) 
        at android.os.Looper.loop(Looper.java:203) 
        at android.app.ActivityThread.main(ActivityThread.java:6251) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924) 

 

package com.example.chayoungyun2;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class calculatorActivity extends AppCompatActivity {



    EditText et_show,et_result;
    Button add,sub,mul,div,remainder,del;
    Button result;
    String history = "";
    String number1 = "";
    String number2 = "";
    int type;
    int ADD = 0;
    int SUB = 1;
    int MUL = 2;
    int DIV = 3;
    int REMAINDER = 4;
    double d1;
    double d2;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        et_show = findViewById(R.id.et_show);
        et_result = findViewById(R.id.et_result);
        et_result.setText("");
        add = findViewById(R.id.btn_add);
        sub = findViewById(R.id.btn_sub);
        mul = findViewById(R.id.btn_mul);
        div = findViewById(R.id.btn_div);
        remainder = findViewById(R.id.btn_remainder);
        del = findViewById(R.id.btn_del);
        result = findViewById(R.id.btn_result);
        add.setOnClickListener(mListener);
        sub.setOnClickListener(mListener);
        mul.setOnClickListener(mListener);
        div.setOnClickListener(mListener);
        remainder.setOnClickListener(mListener);
        result.setOnClickListener(mListener);
        del.setOnClickListener(mListener);
        
        Button clear = findViewById(R.id.btn_clear);
        clear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                et_show.setText("");
                et_result.setText("");
                d1 = d2 = 0;
                history = number1 = number2 = "";
            }
        });

        Button plus_minus = findViewById(R.id.btn_plus_minus);
        plus_minus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //실수인지 정수인지 판단해서 부호 바꾸기
                if( ( (Double.parseDouble(et_result.getText().toString())) - ((int)Double.parseDouble(et_result.getText().toString())) ) == 0.0 )
                {
                    et_result.setText( "" + (Integer.parseInt(et_result.getText().toString()) * -1) );
                }
                else {
                    et_result.setText( "" + (Double.parseDouble(et_result.getText().toString()) * -1) );
                }

            }
        });
    }

다른곳에서 쓰던거 activity중 하나에다가 넣어줬는데 실행시 오류가뜨네요 ...ㅜㅜ

더웃긴건 됬었는데 갑자기 안된다는 겁니다...  

Main 에서 버튼으로 현재 엑티비티버튼 클릭시 앱실행중지 오류가 뜹니다...

Comments

그밑 자바 파일 입니다.


Button.OnClickListener mListener = new Button.OnClickListener() {
        @Override
        public void onClick(View v) {

            switch (v.getId()) {
                case R.id.btn_add :
                    number1 = et_result.getText().toString();
                    history = et_result.getText().toString() + " + ";
                    et_show.setText(history);
                    et_result.setText("");

                    type = ADD;
                    break;

                case R.id.btn_sub :
                    number1 = et_result.getText().toString();
                    history = et_result.getText().toString() + " - ";
                    et_show.setText(history);
                    et_result.setText("");

                    type = SUB;
                    break;

                case R.id.btn_mul :
                    number1 = et_result.getText().toString();
                    history = et_result.getText().toString() + " * ";
                    et_show.setText(history);
                    et_result.setText("");

                    type = MUL;
                    break;

                case R.id.btn_div :
                    number1 = et_result.getText().toString();
                    history = et_result.getText().toString() + " / ";
                    et_show.setText(history);
                    et_result.setText("");

                    type = DIV;
                    break;

                case R.id.btn_remainder :
                    number1 = et_result.getText().toString();
                    history = et_result.getText().toString() + " % ";
                    et_show.setText(history);
                    et_result.setText("");

                    type = REMAINDER;
                    break;

                case R.id.btn_del :

                    String del_number = et_result.getText().toString();

                    et_result.setText(del_number.substring(0,del_number.length() - 1));
                    break;

                case R.id.btn_result :
                    double result = 0;

                    number2 = et_result.getText().toString();
                    history = history + et_result.getText().toString();
                    et_show.setText(history);

                    d1 = Double.parseDouble(number1);
                    d2 = Double.parseDouble(number2);

                    //number2 = et_result.getText().toString();
                    if(type == ADD) {
                        result = d1 + d2;
                        et_result.setText("" + result);
                    } else if (type == SUB) {
                        result = d1 - d2;
                        et_result.setText("" + result);
                    }else if (type == MUL) {
                        result = d1 * d2;
                        et_result.setText("" + result);
                    }else if (type == DIV) {
                        result = d1 / d2;
                        et_result.setText("" + result);
                    }else if (type == REMAINDER) {
                        result = d1 % d2;
                        et_result.setText("" + result);
                    }

                    number1 = et_result.getText().toString();
                    break;

            }
        }
    };

    public void onClick (View v)
    {
        switch(v.getId()){
            case R.id.btn0 : et_result.setText(et_result.getText().toString() + 0); break;
            case R.id.btn1 : et_result.setText(et_result.getText().toString() + 1); break;
            case R.id.btn2 : et_result.setText(et_result.getText().toString() + 2); break;
            case R.id.btn3 : et_result.setText(et_result.getText().toString() + 3); break;
            case R.id.btn4 : et_result.setText(et_result.getText().toString() + 4); break;
            case R.id.btn5 : et_result.setText(et_result.getText().toString() + 5); break;
            case R.id.btn6 : et_result.setText(et_result.getText().toString() + 6); break;
            case R.id.btn7 : et_result.setText(et_result.getText().toString() + 7); break;
            case R.id.btn8 : et_result.setText(et_result.getText().toString() + 8); break;
            case R.id.btn9 : et_result.setText(et_result.getText().toString() + 9); break;
            case R.id.btndot : et_result.setText(et_result.getText().toString() + "."); break;
        }
    }
}

---

xml입니다


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    tools:context=".calculatorActivity"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/background"
    android:orientation="vertical">


    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <EditText
            android:id="@+id/et_show"
            android:layout_width="match_parent"
            android:layout_height="137dp"
            android:layout_marginTop="66dp"
            android:hint="진행과정"
            android:textColor="#FFFFFF"
            android:textSize="50dp" />



        <EditText
            android:id="@+id/et_result"
            android:layout_width="438dp"
            android:layout_height="126dp"
            android:layout_below="@+id/et_show"
            android:layout_marginTop="36dp"
            android:hint="여기에는 정답이"
            android:textColor="#FFFFFF"
            android:textSize="50dp" />



    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_marginTop="55dp">


        <Button
            android:id="@+id/btn_clear"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="C" />

        <Button
            android:id="@+id/btn_del"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="DEL" />

        <Button
            android:id="@+id/btn_remainder"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="%" />

        <Button
            android:id="@+id/btn_div"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="/" />


    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">



        <Button
            android:onClick="onClick"
            android:id="@+id/btn7"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="7" />

        <Button
            android:onClick="onClick"
            android:id="@+id/btn8"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="8" />

        <Button
            android:onClick="onClick"
            android:id="@+id/btn9"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="9" />

        <Button
            android:id="@+id/btn_mul"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="*" />

    </LinearLayout>


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:onClick="onClick"
            android:id="@+id/btn4"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="4" />

        <Button
            android:onClick="onClick"
            android:id="@+id/btn5"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="5" />

        <Button
            android:onClick="onClick"
            android:id="@+id/btn6"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="6" />

        <Button
            android:id="@+id/btn_sub"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="-" />

    </LinearLayout>


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:onClick="onClick"
            android:id="@+id/btn1"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="1" />

        <Button
            android:onClick="onClick"
            android:id="@+id/btn2"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="2" />

        <Button
            android:onClick="onClick"
            android:id="@+id/btn3"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="3" />

        <Button
            android:id="@+id/btn_add"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="+" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btn_plus_minus"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="±" />

        <Button
            android:onClick="onClick"
            android:id="@+id/btn0"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="0" />

        <Button
            android:onClick="onClick"
            android:id="@+id/btndot"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="." />

        <Button
            android:id="@+id/btn_result"
            android:layout_width="0dp"
            android:layout_height="80dp"
            android:layout_weight="1"
            android:text="=" />


    </LinearLayout>

</LinearLayout>

Answer 1

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.chayoungyun2.calculatorActivity.onCreate(calculatorActivity.java:46)

에 나오듯 calculatorActivity 파일의 46 라인에서 setText 를 부르려 했는데. 해당 객체가 null  이라 FATAL 오류가 발생해서 종료 되었습니다.

메인에서 calculatorActivity  엑티비티를 띄우신 듯 한데..  리소스 파일이름이 activity_main.xml 맞나요? 맞다면 리소스가 꼬인듯 하니 클린 빌드를 하시고,  리소스 파일이름이 다른거면 맞춰 주세요