Java 为什么该计划会给出；“类型”的非法启动；错误？

以下是相关的代码片段：

public static Rand searchCount (int[] x) 
{
    int a ; 
    int b ; 
    int c ; 
    int d ; 
    int f ; 
    int g ;
    int h ; 
    int i ; 
    int j ;
    Rand countA = new Rand () ;
        for (int l= 0; l<x.length; l++) 
        {
            if (x[l] = 0) 
            a++ ;
            else if (x[l] = 1) 
            b++ ;
        }
    }
    return countA ;

}

---

这里怎么了？这个错误消息是什么意思

在

return

语句之前有一个放错位置的右大括号。

在return类型之前有一个额外的“{”。

---

您可能还希望在if和else条件下使用“==”而不是“=”。

hi以下代码适用于android中的AR应用程序。代码给出错误消息： 错误：类型catch的非法开始 在“catch”语句之前，我检查了大量代码，以确定右大括号是否放错位置。还有分号。那么为什么java会给出上述错误？请检查我的代码。也许我检查错了

   public class HelloArActivity<exception> extends 
   AppCompatActivity implements GLSurfaceView.Renderer {
   private static final String TAG = 
   HelloArActivity.class.getSimpleName();


   private GLSurfaceView surfaceView;

   private boolean installRequested;

   private int session;

   Set up tap listener.
   private GestureDetector gestureDetector = new 
   GestureDetector(
    this,
    new GestureDetector.SimpleOnGestureListener() {
      @Override
      public boolean onSingleTapUp(MotionEvent e) {
        onSingleTap(e);
        return true;
      }

      @Override
      public boolean onDown(MotionEvent e) {
        return true;
      }

      @Override
      public void onLongPress(MotionEvent e) {
        onLongPressDown(e);
      }
    });
     private Snackbar messageSnackbar;
     private DisplayRotationHelper displayRotationHelper;

     private final BackgroundRenderer backgroundRenderer = 
     new BackgroundRenderer();
     private final ObjectRenderer virtualObject = new 
     ObjectRenderer();
     private final ObjectRenderer virtualObjectShadow = new 
     ObjectRenderer();
     private final PlaneRenderer planeRenderer = new 
     PlaneRenderer();
     private final PointCloudRenderer pointCloud = new 
     PointCloudRenderer();


     private final float[] anchorMatrix = new float[16];


      private final ArrayBlockingQueue<MotionEvent> 
     queuedSingleTaps = new ArrayBlockingQueue<>(16);
    private final ArrayList<Anchor> anchors = new 
   ArrayList<>();
   private Object UnavailableArcoreNotInstalledException;
   private Object 
   UnavailableUserDeclinedInstallationException;

   @SuppressLint("ClickableViewAccessibility")
   @Override
   protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
   surfaceView = findViewById(R.id.surfaceview);
   displayRotationHelper = new 
   DisplayRotationHelper(/*context=*/ this);

    surfaceView.setOnTouchListener(
    new View.OnTouchListener() {
      @Override
      public boolean onTouch(View v, MotionEvent event) {
        return gestureDetector.onTouchEvent(event);
      }
    });


    surfaceView.setPreserveEGLContextOnPause(true);
    surfaceView.setEGLContextClientVersion(2);
     surfaceView.setEGLConfigChooser(8, 8, 8, 8, 16, 0); // 
    Alpha used for plane blending.
    surfaceView.setRenderer(this);
  




    surfaceView.setRenderMode(GLSurfaceView.RENDERMODE_CONTINUoSLY);

         installRequested = false;
          }

        private void onLongPressDown(MotionEvent e) {
       anchors.clear();
             }

           @Override
            protected void onResume() {
            super.onResume();



         installRequested = false;
         }

        private void onLongPressDown(MotionEvent e) {
        anchors.clear();
        }

        @Override
        protected void onResume() {
        super.onResume();


       Exception exception;
       if (session == Integer.parseInt(null)) {
        exception = null;
         String message = null;

      try {
          session = 0;
          int onDrawFrame = 60;

          Class<Session> frame = new session();
      } catch (IOException e) {
          e.printStackTrace();
      }
      switch (ArCoreApk.getInstance().requestInstall(this, !installRequested)) {
          case INSTALL_REQUESTED:
              installRequested = true;
              return;
          case INSTALLED:
              break;
      }

      // ARCore requires camera permissions to operate. If we did not yet obtain runtime
      // permission on Android M and above, now is a good time to ask the user for it.
      if (!CameraPermissionHelper.hasCameraPermission(this)) {
          CameraPermissionHelper.requestCameraPermission(this);
          return;
      }

      session = new Session(/* context= */ this);
  }
  final UnavailableUserDeclinedInstallationException unavailableUserDeclinedInstallationException = (com.google.ar.core.exceptions.UnavailableUserDeclinedInstallationException) UnavailableUserDeclinedInstallationException;
  {
      message = "Please install ARCore" | (UnavailableArcoreNotInstalledException);
      exception = e;
  }

  final Exception e = new 
  ThreadLocal<UnavailableApkTooOldException>();
  message = "Please update ARCore";
    }
     catch(IOError) {

公共类活动扩展
AppCompatActivity实现GLSurfaceView.Renderer{
私有静态最终字符串标记=
HelloArActivity.class.getSimpleName（）；
私人GLSURFACHEVIEW SURFACHEVIEW；
要求提供私人服务；
非公开会议；
设置tap侦听器。
私人手势检测器手势检测器=新建
手势检测器(
这
新的GestureDetector.SimpleOnGestureListener（）{
@凌驾
公共布尔onSingleTapUp（运动事件e）{
onSingleTap（e）；
返回true；
}
@凌驾
公共布尔onDown（运动事件e）{
返回true；
}
@凌驾
公开无效在线新闻（运动事件e）{
仅长按（e）；
}
});
私有Snackbar消息Snackbar；
私有显示RotationHelper显示RotationHelper；
私人最终背景渲染器背景渲染器=
新背景渲染器（）；
私有最终ObjectRenderer virtualObject=new
ObjectRenderer（）；
私有最终ObjectRenderer virtualObjectShadow=新建
ObjectRenderer（）；
专用最终平面渲染器平面渲染器=新建
平面渲染器（）；
私有最终PointCloudRenderer pointCloud=新建
PointCloudRenderer（）；
私人最终浮动[]主播矩阵=新浮动[16]；
专用最终ArrayBlockingQueue
queuedSingleTaps=新的ArrayBlockingQueue（16）；
私有最终ArrayList锚点=新建
ArrayList（）；
私有对象不可用ArcoreNotInstalledException；
私有对象
UnavailableUserDeclinedInstallationException；
@SuppressLint（“ClickableViewAccessibility”）
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
surfaceView=findViewById（R.id.surfaceView）；
displayRotationHelper=新建
DisplayRotationHelper（/*上下文=*/this）；
surfaceView.setOnTouchListener(
新视图。OnTouchListener（）{
@凌驾
公共布尔onTouch（视图v，运动事件）{
返回gestureDetector.onTouchEvent（事件）；
}
});
surfaceView.setPreserveEGLContextOnPause（true）；
surfaceView.setEGLContextClientVersion（2）；
surfaceView.setEGLConfigChooser（8,8,8,8,16,0）；//
用于平面混合的Alpha。
surfaceView.setRenderer（此）；
surfaceView.setRenderMode（GLSurfaceView.RENDERMODE_连续）；
installrequest=false；
}
仅限私人无效长按（运动事件e）{
锚。清除（）；
}
@凌驾
受保护的void onResume（）{
super.onResume（）；
installrequest=false；
}
仅限私人无效长按（运动事件e）{
锚。清除（）；
}
@凌驾
受保护的void onResume（）{
super.onResume（）；
例外情况；
if（session==Integer.parseInt（null））{
异常=空；
字符串消息=null；
试一试{
会话=0；
int onDrawFrame=60；
类框架=新会话（）；
}捕获（IOE异常）{
e、 printStackTrace（）；
}
开关（ArCoreApk.getInstance（）.requestInstall（this，！installRequested））{
要求安装的案例：
installrequest=true；
返回；
已安装的机箱：
打破
}
//ARCore需要摄像头权限才能操作。如果我们尚未获得运行时
//安卓M及以上版本的权限，现在是向用户申请的好时机。
如果（！CameraPermissionHelper.hasCameraPermission（此））{
CameraPermissionHelper.requestCameraPermission（此）；
返回；
}
会话=新会话（/*context=*/this）；
}
最终不可用UserDeclinedInstallationException不可用UserDeclinedInstallationException=（com.google.ar.core.exceptions.UnavailableUserDeclinedInstallationException）不可用UserDeclinedInstallationException；
{
message=“请安装ARCore”|（不可用ArcoreNotInstalledException）；
例外=e；
}
最终例外情况e=新
ThreadLocal（）；
message=“请更新ARCore”；
}
捕获（IOError）{

此外，如果（x[l]=0）可能不是预期的，您的意思是如果（x[l]=0）？

   public class HelloArActivity<exception> extends 
   AppCompatActivity implements GLSurfaceView.Renderer {
   private static final String TAG = 
   HelloArActivity.class.getSimpleName();


   private GLSurfaceView surfaceView;

   private boolean installRequested;

   private int session;

   Set up tap listener.
   private GestureDetector gestureDetector = new 
   GestureDetector(
    this,
    new GestureDetector.SimpleOnGestureListener() {
      @Override
      public boolean onSingleTapUp(MotionEvent e) {
        onSingleTap(e);
        return true;
      }

      @Override
      public boolean onDown(MotionEvent e) {
        return true;
      }

      @Override
      public void onLongPress(MotionEvent e) {
        onLongPressDown(e);
      }
    });
     private Snackbar messageSnackbar;
     private DisplayRotationHelper displayRotationHelper;

     private final BackgroundRenderer backgroundRenderer = 
     new BackgroundRenderer();
     private final ObjectRenderer virtualObject = new 
     ObjectRenderer();
     private final ObjectRenderer virtualObjectShadow = new 
     ObjectRenderer();
     private final PlaneRenderer planeRenderer = new 
     PlaneRenderer();
     private final PointCloudRenderer pointCloud = new 
     PointCloudRenderer();


     private final float[] anchorMatrix = new float[16];


      private final ArrayBlockingQueue<MotionEvent> 
     queuedSingleTaps = new ArrayBlockingQueue<>(16);
    private final ArrayList<Anchor> anchors = new 
   ArrayList<>();
   private Object UnavailableArcoreNotInstalledException;
   private Object 
   UnavailableUserDeclinedInstallationException;

   @SuppressLint("ClickableViewAccessibility")
   @Override
   protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
   surfaceView = findViewById(R.id.surfaceview);
   displayRotationHelper = new 
   DisplayRotationHelper(/*context=*/ this);

    surfaceView.setOnTouchListener(
    new View.OnTouchListener() {
      @Override
      public boolean onTouch(View v, MotionEvent event) {
        return gestureDetector.onTouchEvent(event);
      }
    });


    surfaceView.setPreserveEGLContextOnPause(true);
    surfaceView.setEGLContextClientVersion(2);
     surfaceView.setEGLConfigChooser(8, 8, 8, 8, 16, 0); // 
    Alpha used for plane blending.
    surfaceView.setRenderer(this);
  




    surfaceView.setRenderMode(GLSurfaceView.RENDERMODE_CONTINUoSLY);

         installRequested = false;
          }

        private void onLongPressDown(MotionEvent e) {
       anchors.clear();
             }

           @Override
            protected void onResume() {
            super.onResume();



         installRequested = false;
         }

        private void onLongPressDown(MotionEvent e) {
        anchors.clear();
        }

        @Override
        protected void onResume() {
        super.onResume();


       Exception exception;
       if (session == Integer.parseInt(null)) {
        exception = null;
         String message = null;

      try {
          session = 0;
          int onDrawFrame = 60;

          Class<Session> frame = new session();
      } catch (IOException e) {
          e.printStackTrace();
      }
      switch (ArCoreApk.getInstance().requestInstall(this, !installRequested)) {
          case INSTALL_REQUESTED:
              installRequested = true;
              return;
          case INSTALLED:
              break;
      }

      // ARCore requires camera permissions to operate. If we did not yet obtain runtime
      // permission on Android M and above, now is a good time to ask the user for it.
      if (!CameraPermissionHelper.hasCameraPermission(this)) {
          CameraPermissionHelper.requestCameraPermission(this);
          return;
      }

      session = new Session(/* context= */ this);
  }
  final UnavailableUserDeclinedInstallationException unavailableUserDeclinedInstallationException = (com.google.ar.core.exceptions.UnavailableUserDeclinedInstallationException) UnavailableUserDeclinedInstallationException;
  {
      message = "Please install ARCore" | (UnavailableArcoreNotInstalledException);
      exception = e;
  }

  final Exception e = new 
  ThreadLocal<UnavailableApkTooOldException>();
  message = "Please update ARCore";
    }
     catch(IOError) {