Java 点击ImageView会导致应用程序崩溃

我认为问题出在counter.getTag（）.toString（）行中。我试图将其放入字符串中，然后将其传递给

tappedCounter

，但我的应用程序仍然崩溃

如果有人能帮助我了解如何在Android Studio中使用logcat解决类似问题，那将非常有帮助

这是日志：

12-22 02:09:59.790 14251-14251/com.example.msq.practice E/AndroidRuntime: FATAL EXCEPTION: main
                                                                          Process: com.example.msq.practice, PID: 14251
                                                                          java.lang.IllegalStateException: Could not execute method for android:onClick
                                                                              at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
                                                                              at android.view.View.performClick(View.java:6256)
                                                                              at android.view.View$PerformClick.run(View.java:24701)
                                                                              at android.os.Handler.handleCallback(Handler.java:789)
                                                                              at android.os.Handler.dispatchMessage(Handler.java:98)
                                                                              at android.os.Looper.loop(Looper.java:164)
                                                                              at android.app.ActivityThread.main(ActivityThread.java:6541)
                                                                              at java.lang.reflect.Method.invoke(Native Method)
                                                                              at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                                                                              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
                                                                           Caused by: java.lang.reflect.InvocationTargetException
                                                                              at java.lang.reflect.Method.invoke(Native Method)
                                                                              at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
                                                                              at android.view.View.performClick(View.java:6256) 
                                                                              at android.view.View$PerformClick.run(View.java:24701) 
                                                                              at android.os.Handler.handleCallback(Handler.java:789) 
                                                                              at android.os.Handler.dispatchMessage(Handler.java:98) 
                                                                              at android.os.Looper.loop(Looper.java:164) 
                                                                              at android.app.ActivityThread.main(ActivityThread.java:6541) 
                                                                              at java.lang.reflect.Method.invoke(Native Method) 
                                                                              at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
                                                                              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767) 
                                                                           Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
                                                                              at com.example.msq.practice.MainActivity.click(MainActivity.java:27)
                                                                              at java.lang.reflect.Method.invoke(Native Method) 
                                                                              at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
                                                                              at android.view.View.performClick(View.java:6256) 
                                                                              at android.view.View$PerformClick.run(View.java:24701) 
                                                                              at android.os.Handler.handleCallback(Handler.java:789) 
                                                                              at android.os.Handler.dispatchMessage(Handler.java:98) 
                                                                              at android.os.Looper.loop(Looper.java:164) 
                                                                              at android.app.ActivityThread.main(ActivityThread.java:6541) 
                                                                              at java.lang.reflect.Method.invoke(Native Method) 
                                                                              at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
                                                                              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767) 

主要活动：-

    package com.example.msq.practice;

    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.widget.ImageView;
    import android.view.View;

    public class MainActivity extends AppCompatActivity {

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

        int activePlayer = 0;
        int[] gameState = {2,2,2,2,2,2,2,2,2};
        int[][] winningPositions = {{1,2,3}, {4,5,6}, {7,8,9}, {0,3,6},                 
        {1,4,7,}, {2,5,8}, {0,4,8}, {2,4,6}};
        boolean isGameActive = true;
        String result;
        String tag;

        public void click(View view){

            ImageView counter = (ImageView) view;

            tag = counter.getTag().toString();

            int tappedCounter = Integer.parseInt(tag);

            if(gameState[tappedCounter] == 2 && isGameActive == true){

                counter.setTranslationY(-5000f);

                gameState[tappedCounter] = activePlayer;
                if(activePlayer == 0){
                    counter.setImageResource(R.drawable.circle);
                    activePlayer = 1;
                }
                else{
                    counter.setImageResource(R.drawable.cross);
                    activePlayer = 0;
                }



 counter.animate().rotation(360f).translationYBy(5000f).setDuration(1000);

    }

    for(int[] winningPosition : winningPositions){

        if(gameState[winningPosition[0]] == gameState[winningPosition[1]] &&
                gameState[winningPosition[1]] == gameState[winningPosition[2]] &&
                gameState[winningPosition[0]] != 2){

            isGameActive = false;

            if(gameState[winningPosition[0]]==0){
                result = "PLayer 1 Won !";
            }
            else{
                result = "PLayer 2 Won !";
            }

        }
        else{

            boolean isGameOver = true;
            for(int counterState : gameState){
                if(counterState == 2) isGameOver = false;
            }

            if(isGameOver)
                result = "It's a Draw";

        }
    }
}

    }

activity_main.xml文件：-

   <?xml version="1.0" encoding="utf-8"?>
   <android.support.constraint.ConstraintLayout 
   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:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context="com.example.msq.practice.MainActivity">



      <GridLayout


        android:id="@+id/gLayout"
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:layout_marginBottom="106dp"
        android:layout_marginEnd="42dp"
        android:layout_marginStart="42dp"
        android:layout_marginTop="105dp"
        android:background="@drawable/board"
        android:columnCount="3"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:rowCount="3">

        <ImageView
            android:id="@+id/imageView0"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_column="0"
            android:layout_marginStart="10dp"
            android:layout_marginTop="10dp"
            android:layout_row="0"
            android:contentDescription="@string/cross"
            android:onClick="click" />

        <ImageView
            android:id="@+id/imageView1"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_column="1"
            android:layout_marginStart="20dp"
            android:layout_marginTop="10dp"
            android:layout_row="0"
            android:contentDescription="@string/cross"
            android:onClick="click" />

        <ImageView
            android:id="@+id/imageView3"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_column="0"
            android:layout_marginStart="10dp"
            android:layout_marginTop="22dp"
            android:layout_row="1"
            android:contentDescription="@string/cross"
            android:onClick="click" />

        <ImageView
            android:id="@+id/imageView4"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_column="1"
            android:layout_marginStart="20dp"
            android:layout_marginTop="22dp"
            android:layout_row="1"
            android:contentDescription="@string/cross"
            android:onClick="click" />

        <ImageView
            android:id="@+id/imageView5"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_column="2"
            android:layout_marginStart="20dp"
            android:layout_marginTop="22dp"
            android:layout_row="1"
            android:contentDescription="@string/cross"
            android:onClick="click"/>

        <ImageView
            android:id="@+id/imageView7"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_column="1"
            android:layout_marginStart="20dp"
            android:layout_marginTop="22dp"
            android:layout_row="2"
            android:contentDescription="@string/cross"
            android:onClick="click" />

        <ImageView
            android:id="@+id/imageView8"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_column="2"
            android:layout_marginStart="20dp"
            android:layout_marginTop="22dp"
            android:layout_row="2"
            android:contentDescription="@string/cross"
            android:onClick="click" />

        <ImageView
            android:id="@+id/imageView6"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_column="0"
            android:layout_marginStart="10dp"
            android:layout_marginTop="22dp"
            android:layout_row="2"
            android:contentDescription="@string/cross"
            android:onClick="click" />

        <ImageView
            android:id="@+id/imageView2"
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:layout_column="2"
            android:layout_marginStart="22dp"
            android:layout_marginTop="10dp"
            android:layout_row="0"
            android:contentDescription="@string/cross"
            android:onClick="click"/>


    </GridLayout>
</android.support.constraint.ConstraintLayout>

您没有在应用程序或xml中的任何位置设置标记。所以getTag将返回null。如果希望视图具有标记，则必须添加该标记。

日志猫的部分确定了崩溃的原因。若您仔细阅读日志，崩溃的最后一个原因是

NullPointerException

原因：java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法“java.lang.String java.lang.Object.toString（）”

---

现在，您正试图使用

getTag（）

获取标记的值，但您尚未在XML布局中的任何

ImageView

上设置任何标记。因此，当调用

toString

时，标记为

null

抛出异常。

两个答案似乎都是正确的。如果他们对你不起作用，请解释原因。哦，现在我明白了，谢谢你，并将其标记为正确答案，以便其他人能从中受益@Msq-9