Android：アプリをMainActvityに追加した後にクラッシュする

-1

私はカウントダウンの部分とボタンを追加してカウントをMainActivity.javaファイルに追加すると、バスケットボールの試合をスコアリングするアプリを開発中ですが、アプリはうまく構築されますがクラッシュします毎回。ここに私が使用したコードがあります。ここは、エラーがあなたがonCreate前findViewByIdを呼び出すことはできません私はアプリAndroid：アプリをMainActvityに追加した後にクラッシュする

E/AndroidRuntime: FATAL EXCEPTION: main 
        Process: com.example.abdulkarim.courtcounter, PID: 19740 
        java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.abdulkarim.courtcounter/com.example.abdulkarim.courtcounter.MainActivity}: java.lang.NullPointerException 
         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2306) 
         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471) 
         at android.app.ActivityThread.access$900(ActivityThread.java:175) 
         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308) 
         at android.os.Handler.dispatchMessage(Handler.java:102) 
         at android.os.Looper.loop(Looper.java:146) 
         at android.app.ActivityThread.main(ActivityThread.java:5603) 
         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:1283) 
         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099) 
         at dalvik.system.NativeStart.main(Native Method) 
        Caused by: java.lang.NullPointerException 
         at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:116) 
         at android.support.v7.app.AppCompatDelegateImplV9.<init>(AppCompatDelegateImplV9.java:147) 
         at android.support.v7.app.AppCompatDelegateImplV11.<init>(AppCompatDelegateImplV11.java:27) 
         at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:50) 
         at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:201) 
         at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:181) 
         at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:521) 
         at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:190) 
         at com.example.abdulkarim.courtcounter.MainActivity.<init>(MainActivity.java:14) 
         at java.lang.Class.newInstanceImpl(Native Method) 
         at java.lang.Class.newInstance(Class.java:1208) 
         at android.app.Instrumentation.newActivity(Instrumentation.java:1067) 
         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2297) 
         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471)  
         at android.app.ActivityThread.access$900(ActivityThread.java:175)  
         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308)  
         at android.os.Handler.dispatchMessage(Handler.java:102)  
         at android.os.Looper.loop(Looper.java:146)  
         at android.app.ActivityThread.main(ActivityThread.java:5603)  
         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:1283)  
         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)  
         at dalvik.system.NativeStart.main(Native Method)

MainActivity.java

package com.example.abdulkarim.courtcounter; 

import android.os.CountDownTimer; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.View; 
import android.widget.Button; 
import android.widget.TextView; 

public class MainActivity extends AppCompatActivity { 

    int scoreTeamA = 0, scoreTeamB = 0; 
    TextView minutes = (TextView) findViewById(R.id.min_counter); 
    TextView seconds = (TextView) findViewById(R.id.sec_counter); 
    long milliLeft, min, sec; 
    CountDownTimer gameTime; 
    final Button timeoutButton = (Button) findViewById(R.id.timeout_button); 

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

    /** 
    * This method is called when the +3 points button is clicked 
    */ 
    public void threePointsA(View view){ 
     scoreTeamA = scoreTeamA + 3; 
     displayScoreA(scoreTeamA); 
    } 

    /** 
    * This method is called when the +2 points button is clicked 
    */ 
    public void twoPointsA(View view){ 
     scoreTeamA = scoreTeamA + 2; 
     displayScoreA(scoreTeamA); 
    } 

    /** 
    * This method is called when the Free Throw button is clicked 
    */ 
    public void freeThrowA(View view){ 
     scoreTeamA = scoreTeamA + 1; 
     displayScoreA(scoreTeamA); 
    } 

    /** 
    * This method is called when the +3 points button is clicked 
    */ 
    public void threePointsB(View view){ 
     scoreTeamB = scoreTeamB + 3; 
     displayScoreB(scoreTeamB); 
    } 

    /** 
    * This method is called when the +2 points button is clicked 
    */ 
    public void twoPointsB(View view){ 
     scoreTeamB = scoreTeamB + 2; 
     displayScoreB(scoreTeamB); 
    } 

    /** 
    * This method is called when the Free Throw button is clicked 
    */ 
    public void freeThrowB(View view){ 
     scoreTeamB = scoreTeamB + 1; 
     displayScoreB(scoreTeamB); 
    } 

    /** 
    * This method is called when the reset button is clicked 
    */ 
    public void reset(View view){ 
     scoreTeamA = 0; 
     scoreTeamB = 0; 
     displayScoreA(scoreTeamA); 
     displayScoreB(scoreTeamB); 
    } 

    /** 
    * This method initializes the countdown timer 
    */ 
    public void gameTime(long timeLengthMilli) { 
     gameTime = new CountDownTimer(timeLengthMilli, 1000) { 

      @Override 
      public void onTick(long milliTillFinish) { 
       milliLeft = milliTillFinish; 
       min = (milliTillFinish/(1000 * 60)); 
       sec = ((milliTillFinish/1000) - min * 60); 
       minutes.setText(Long.toString(min)); 
       seconds.setText(Long.toString(sec)); 
       Log.i("Tick", "Tock"); 
      } 
      public void onFinish() { 
       minutes.setText("00"); 
       seconds.setText("00"); 
      } 
     }.start(); 

    } 

    public void timerPause() { 
     gameTime.cancel(); 
    } 

    private void timerResume() { 
     Log.i("min", Long.toString(min)); 
     Log.i("Sec", Long.toString(sec)); 
     gameTime(milliLeft); 
    } 

    /** 
    *This method is called when the timeOut button is clicked 
    */ 
    public void timeOut(View view){ 
     timeoutButton.setOnClickListener(new View.OnClickListener() { 
      public void onClick(View v) { 
       if(timeoutButton.getText().equals("Start")){ 
        Log.i("Started", timeoutButton.getText().toString()); 
        timeoutButton.setText("Timeout"); 
        gameTime(60*1000); 
       } else if (timeoutButton.getText().equals("Pause")){ 
        Log.i("Timeout", timeoutButton.getText().toString()); 
        timeoutButton.setText("Resume"); 
        timerPause(); 
       } else if (timeoutButton.getText().equals("Resume")){ 
        timeoutButton.setText("Timeout"); 
        timerResume(); 
       } 
      } 
     }); 
    } 
    /** 
    * This method handles the display of scores for team A 
    */ 
    private void displayScoreA(int score){ 
     TextView scoreTextView = (TextView) findViewById(R.id.teamA_score_text_view); 
     scoreTextView.setText(String.valueOf(score)); 
    } 
    /** 
    * This method handles the display of scores for team A 
    */ 
    private void displayScoreB(int score){ 
     TextView scoreTextView = (TextView) findViewById(R.id.teamB_score_text_view); 
     scoreTextView.setText(String.valueOf(score)); 
    } 
}

main_activity.xml

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:id="@+id/activity_main" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    tools:context="com.example.abdulkarim.courtcounter.MainActivity"> 

    <RelativeLayout 
     android:id="@+id/r1_layout" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentTop="true" 
     android:layout_centerHorizontal="true"> 
     <TextView 
      android:id="@+id/min_text_view" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_marginLeft="20dp" 
      android:layout_marginRight="75dp" 
      android:paddingTop="16dp" 
      android:text="Mins" 
      android:textAllCaps="true" 
      android:textColor="@android:color/black" 
      android:textSize="10sp" /> 

     <TextView 
      android:id="@+id/sec_text_view" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_alignParentTop="true" 
      android:paddingTop="16dp" 
      android:layout_toRightOf="@id/min_text_view" 
      android:text="Secs" 
      android:textAllCaps="true" 
      android:textColor="@android:color/black" 
      android:textSize="10sp" /> 

     <TextView 
      android:id="@+id/min_counter" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_below="@id/min_text_view" 
      android:layout_marginTop="8dp" 
      android:fontFamily="sans-serif-light" 
      android:text="00" 
      android:textColor="#000000" 
      android:textSize="56sp" /> 

     <TextView 
      android:id="@+id/blinker_text_view" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_below="@id/min_text_view" 
      android:layout_marginTop="8dp" 
      android:layout_toRightOf="@id/min_counter" 
      android:fontFamily="sans-serif-light" 
      android:paddingLeft="16dp" 
      android:paddingRight="16dp" 
      android:text=":" 
      android:textColor="#000000" 
      android:textSize="56sp" /> 

     <TextView 
      android:id="@+id/sec_counter" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_below="@id/min_text_view" 
      android:layout_marginTop="8dp" 
      android:layout_toRightOf="@id/blinker_text_view" 
      android:fontFamily="sans-serif-light" 
      android:text="00" 
      android:textColor="#000000" 
      android:textSize="56sp" /> 
    </RelativeLayout> 

    <LinearLayout 
     android:id="@+id/l1_layout" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_below="@id/r1_layout" 
     android:orientation="horizontal"> 

     <LinearLayout 
      android:layout_width="0dp" 
      android:layout_height="wrap_content" 
      android:layout_weight="1" 
      android:orientation="vertical"> 

      <TextView 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginTop="16dp" 
       android:fontFamily="sans-serif-medium" 
       android:gravity="center_horizontal" 
       android:text="Team A" 
       android:textColor="#616161" 
       android:textSize="14sp" /> 

      <TextView 
       android:id="@+id/teamA_score_text_view" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginTop="16dp" 
       android:fontFamily="sans-serif-light" 
       android:gravity="center_horizontal" 
       android:text="0" 
       android:textColor="#000000" 
       android:textSize="56sp" /> 

      <Button 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginBottom="8dp" 
       android:layout_marginLeft="24dp" 
       android:layout_marginRight="24dp" 
       android:layout_marginTop="24dp" 
       android:fontFamily="sans-serif-medium" 
       android:onClick="threePointsA" 
       android:text="+3 Points" 
       android:textAllCaps="true" 
       android:textColor="#616161" 
       android:textSize="14sp" /> 

      <Button 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginBottom="8dp" 
       android:layout_marginLeft="24dp" 
       android:layout_marginRight="24dp" 
       android:fontFamily="sans-serif-medium" 
       android:onClick="twoPointsA" 
       android:text="+2 Points" 
       android:textAllCaps="true" 
       android:textColor="#616161" 
       android:textSize="14sp" /> 

      <Button 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginBottom="8dp" 
       android:layout_marginLeft="24dp" 
       android:layout_marginRight="24dp" 
       android:fontFamily="sans-serif-medium" 
       android:onClick="freeThrowA" 
       android:text="Free Throw" 
       android:textAllCaps="true" 
       android:textColor="#616161" 
       android:textSize="14sp" /> 
     </LinearLayout> 

     <View 
      android:layout_width="1dp" 
      android:layout_height="match_parent" 
      android:layout_marginTop="16dp" 
      android:background="@android:color/darker_gray"></View> 

     <LinearLayout 
      android:layout_width="0dp" 
      android:layout_height="wrap_content" 
      android:layout_weight="1" 

      android:orientation="vertical"> 

      <TextView 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginTop="16dp" 
       android:fontFamily="sans-serif-medium" 
       android:gravity="center_horizontal" 
       android:text="Team B" 
       android:textColor="#616161" 
       android:textSize="14sp" /> 

      <TextView 
       android:id="@+id/teamB_score_text_view" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginTop="16dp" 
       android:fontFamily="sans-serif-light" 
       android:gravity="center_horizontal" 
       android:text="0" 
       android:textColor="#000000" 
       android:textSize="56sp" /> 

      <Button 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginBottom="8dp" 
       android:layout_marginLeft="24dp" 
       android:layout_marginRight="24dp" 
       android:layout_marginTop="24dp" 
       android:fontFamily="sans-serif-medium" 
       android:onClick="threePointsB" 
       android:text="+3 Points" 
       android:textAllCaps="true" 
       android:textColor="#616161" 
       android:textSize="14sp" /> 

      <Button 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginBottom="8dp" 
       android:layout_marginLeft="24dp" 
       android:layout_marginRight="24dp" 
       android:fontFamily="sans-serif-medium" 
       android:onClick="twoPointsB" 
       android:text="+2 Points" 
       android:textAllCaps="true" 
       android:textColor="#616161" 
       android:textSize="14sp" /> 

      <Button 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginBottom="8dp" 
       android:layout_marginLeft="24dp" 
       android:layout_marginRight="24dp" 
       android:fontFamily="sans-serif-medium" 
       android:onClick="freeThrowB" 
       android:text="Free Throw" 
       android:textAllCaps="true" 
       android:textColor="#616161" 
       android:textSize="14sp" /> 
     </LinearLayout> 

    </LinearLayout> 


    <LinearLayout 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:orientation="horizontal" 
     android:layout_alignParentBottom="true" 
     android:layout_centerHorizontal="true"> 
     <Button 
      android:id="@+id/timeout_button" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_marginRight="8dp" 
      android:layout_marginBottom="32dp" 
      android:layout_marginLeft="16dp" 
      android:text="Start" 
      android:fontFamily="sans-serif-medium" 
      android:textAllCaps="true" 
      android:textColor="#616161" 
      android:textSize="14sp" 
      android:onClick="timeOut"/> 
    <Button 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentBottom="true" 
     android:layout_centerHorizontal="true" 
     android:layout_marginBottom="32dp" 
     android:layout_marginRight="16dp" 
     android:layout_marginLeft="8dp" 
     android:fontFamily="sans-serif-medium" 
     android:onClick="Reset" 
     android:text="Reset" 
     android:textAllCaps="true" 
     android:textColor="#616161" 
     android:textSize="14sp" /> 
    </LinearLayout> 

</RelativeLayout>

出典

2016-10-08 Abdulrahman Abdulkarim

あなたはOnCreateの方法でビューを初期化すると仮定アレント？ –

私は仲間を知らないので、アンドロイドかジャワで2日前に始めたので、私はまだ学んでいます –

あなたが望むならば、グローバルに宣言しますが、それらを初期化する方法は –

を起動しようとするたびに生成されています方法。
ビュー参照の初期化をonCreateの中に移動します。

public class MainActivity extends AppCompatActivity { 

    int scoreTeamA = 0, scoreTeamB = 0; 
    TextView minutes; 
    TextView seconds; 
    long milliLeft, min, sec; 
    CountDownTimer gameTime; 
    Button timeoutButton; 

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

     minutes = (TextView) findViewById(R.id.min_counter); 
     seconds = (TextView) findViewById(R.id.sec_counter); 
     timeoutButton = (Button) findViewById(R.id.timeout_button); 
    }

出典

2016-10-08 16:41:55

あなたが誰かの質問の間違った部分を投稿したとき。あなたは修正された部分も置くことになっています。 –

最終的にここに来る前に、私はそれらをonCreateに移動してコード全体にアクセスできなくなってしまいました。 –

@MohammedAtif編集の回答 –

はのonCreateメソッドのグローバル

移動findViewById内のすべての変数を宣言します。グローバルではなくonCreateメソッド内で初期化する必要があります。

public class MainActivity extends AppCompatActivity { 
    int scoreTeamA = 0, scoreTeamB = 0; 
    TextView minutes; 
    TextView seconds; 
    long milliLeft, min, sec; 
    CountDownTimer gameTime; 
    final Button timeoutButton; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     minutes = (TextView) findViewById(R.id.min_counter); 
     seconds = (TextView) findViewById(R.id.sec_counter); 
     timeoutButton = (Button) findViewById(R.id.timeout_button); 
    } 
      // others code...  
}

出典

2016-10-08 17:00:16

Android：アプリをMainActvityに追加した後にクラッシュする

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