错误：“无法实例化类型Intent”
目标：根据gridView位置值
启动新意图请求：协助解决上面指定的错误
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
ImageCell i = (ImageCell) v;
trace("onItemClick in view: " + i.mCellNumber);
Toast.makeText(DragActivity.this, "" + position, Toast.LENGTH_SHORT).show();
switch (position) {
case 0:
// start one activity
Intent intent = new Intent(DragActivity.this, Activity1.class);
startActivity(intent);
break;
case 1:
// start another activity
break;
// etc.
default:
Toast.makeText(DragActivity.this, "Default", Toast.LENGTH_SHORT).show();
}
}
我不确定我做错了什么（我尝试添加正确的导入等但我不知道还能做些什么来解决这个问题）非常感谢任何建议。
import android.app.Activity;
import android.os.Bundle;
import android.content.Intent;
import android.util.Log;
import android.view.Gravity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.FrameLayout;
import android.widget.GridView;
import android.widget.TextView;
import android.widget.Toast;
public class DragActivity extends Activity implements
View.OnLongClickListener, View.OnClickListener, View.OnTouchListener{
/**
*/
// Constants
private static final int HIDE_TRASHCAN_MENU_ID = Menu.FIRST;
private static final int SHOW_TRASHCAN_MENU_ID = Menu.FIRST + 1;
private static final int ADD_OBJECT_MENU_ID = Menu.FIRST + 2;
private static final int CHANGE_TOUCH_MODE_MENU_ID = Menu.FIRST + 3;
private boolean isErase = true;
private EditText et;
private TextView tx;
/**
*/
// Variables
private DragController mDragController; // Object that handles a drag-drop
// sequence. It intersacts with
// DragSource and DropTarget
// objects.
private DragLayer mDragLayer; // The ViewGroup within which an object can be
// dragged.
private DeleteZone mDeleteZone; // A drop target that is used to remove
// objects from the screen.
private int mImageCount = 0; // The number of images that have been added to
// screen.
private ImageCell mLastNewCell = null; // The last ImageCell added to the
// screen when Add Image is clicked.
private boolean mLongClickStartsDrag = true; // If true, it takes a long
// click to start the drag
// operation.
// Otherwise, any touch
// event starts a drag.
public static final boolean Debugging = false; // Use this to see extra
// toast messages.
/**
*/
// Methods
/**
* Add a new image so the user can move it around. It shows up in the
* image_source_frame part of the screen.
*
* @param resourceId
* int - the resource id of the image to be added
*/
public void addNewImageToScreen(int resourceId) {
if (mLastNewCell != null)
mLastNewCell.setVisibility(View.GONE);
FrameLayout imageHolder = (FrameLayout) findViewById(R.id.image_source_frame);
if (imageHolder != null) {
FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT,
Gravity.CENTER);
ImageCell newView = new ImageCell(this);
newView.setImageResource(resourceId);
imageHolder.addView(newView, lp);
newView.mEmpty = false;
newView.mCellNumber = -1;
mLastNewCell = newView;
mImageCount++;
// Have this activity listen to touch and click events for the view.
newView.setOnClickListener(this);
newView.setOnLongClickListener(this);
newView.setOnTouchListener(this);
}
}
/**
* Add one of the images to the screen so the user has a new image to move
* around. See addImageToScreen.
*
*/
public void addNewImageToScreen() {
int resourceId = R.drawable.sqwhite;
addNewTextToScreen();
int m = mImageCount % 3;
if (m == 1)
resourceId = R.drawable.sqdrk;
else if (m == 2)
resourceId = R.drawable.sqwhite;
addNewImageToScreen(resourceId);
}
private void addNewTextToScreen() {
// TODO Auto-generated method stub
// et.setVisibility(View.VISIBLE);
if (isErase) {
tx.setText(et.getText().toString());
} else {
tx.setText("");
et.setVisibility(View.GONE);
}
isErase = !isErase;
}
/**
* Handle a click on a view.
*
*/
public void onClick(View v) {
if (mLongClickStartsDrag) {
// Tell the user that it takes a long click to start dragging.
// toast("Press and hold to drag an image.");
positionListener();
onItemClick(null, v, mImageCount, mImageCount);
}
}
private void positionListener() {
// TODO Auto-generated method stub
// GridView gridView = (GridView) findViewById(R.id.image_grid_view);
// gridView.setOnItemClickListener(new OnItemClickListener() {
// public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
// Toast.makeText(DragActivity.this, "" + position, Toast.LENGTH_SHORT).show();
// }
// });
}
/**
* Handle a click of the Add Image button
*
*/
public void onClickAddImage(View v) {
addNewImageToScreen();
}
// public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
// Toast.makeText(DragActivity.this, "" + position, Toast.LENGTH_SHORT).show();
// }
/**
* onCreate - called when the activity is first created.
*
* Creates a drag controller and sets up three views so click and long click
* on the views are sent to this activity. The onLongClick method starts a
* drag sequence.
*
*/
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.demo);
et = (EditText) findViewById(R.id.editText1);
et.setVisibility(View.INVISIBLE);
tx = (TextView) findViewById(R.id.textView1);
GridView gridView = (GridView) findViewById(R.id.image_grid_view);
if (gridView == null)
toast("Unable to find GridView");
else {
gridView.setAdapter(new ImageCellAdapter(this));
// gridView.setOnItemClickListener (this);
}
mDragController = new DragController(this);
mDragLayer = (DragLayer) findViewById(R.id.drag_layer);
mDragLayer.setDragController(mDragController);
mDragLayer.setGridView(gridView);
mDragController.setDragListener(mDragLayer);
// mDragController.addDropTarget (mDragLayer);
mDeleteZone = (DeleteZone) findViewById(R.id.delete_zone_view);
// Give the user a little guidance.
Toast.makeText(getApplicationContext(),
getResources().getString(R.string.instructions),
Toast.LENGTH_LONG).show();
}
/**
* Build a menu for the activity.
*
*/
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
menu.add(0, HIDE_TRASHCAN_MENU_ID, 0, "Hide Trashcan").setShortcut('1',
'c');
menu.add(0, SHOW_TRASHCAN_MENU_ID, 0, "Show Trashcan").setShortcut('2',
'c');
menu.add(0, ADD_OBJECT_MENU_ID, 0, "Add View").setShortcut('9', 'z');
menu.add(0, CHANGE_TOUCH_MODE_MENU_ID, 0, "Change Touch Mode");
return true;
}
/**
* Handle a click of an item in the grid of cells.
*
*/
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
ImageCell i = (ImageCell) v;
trace("onItemClick in view: " + i.mCellNumber);
Toast.makeText(DragActivity.this, "" + position, Toast.LENGTH_SHORT).show();
switch (position) {
case 0:
// start one activity
Intent intent = new Intent(DragActivity.this, Activity1.class);
startActivity(intent);
break;
case 1:
// start another activity
break;
// etc.
default:
// unknown type! based on the language,
// there should probably be some error-handling
// here, maybe an exception
Toast.makeText(DragActivity.this, "Default", Toast.LENGTH_SHORT).show();
}
}
/**
* Handle a long click. If mLongClick only is true, this will be the only
* way to start a drag operation.
*
* @param v
* View
* @return boolean - true indicates that the event was handled
*/
public boolean onLongClick(View v) {
if (mLongClickStartsDrag) {
// trace ("onLongClick in view: " + v + " touchMode: " +
// v.isInTouchMode ());
// Make sure the drag was started by a long press as opposed to a
// long click.
// (Note: I got this from the Workspace object in the Android
// Launcher code.
// I think it is here to ensure that the device is still in touch
// mode as we start the drag operation.)
if (!v.isInTouchMode()) {
toast("isInTouchMode returned false. Try touching the view again.");
return false;
}
return startDrag(v);
}
// If we get here, return false to indicate that we have not taken care
// of the event.
return false;
}
/**
* Perform an action in response to a menu item being clicked.
*
*/
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case HIDE_TRASHCAN_MENU_ID:
if (mDeleteZone != null)
mDeleteZone.setVisibility(View.INVISIBLE);
return true;
case SHOW_TRASHCAN_MENU_ID:
if (mDeleteZone != null)
mDeleteZone.setVisibility(View.VISIBLE);
return true;
case ADD_OBJECT_MENU_ID:
// Add a new object to the screen;
addNewImageToScreen();
return true;
case CHANGE_TOUCH_MODE_MENU_ID:
mLongClickStartsDrag = !mLongClickStartsDrag;
String message = mLongClickStartsDrag ? "Changed touch mode. Drag now starts on long touch (click)."
: "Changed touch mode. Drag now starts on touch (click).";
Toast.makeText(getApplicationContext(), message, Toast.LENGTH_LONG)
.show();
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* This is the starting point for a drag operation if mLongClickStartsDrag
* is false. It looks for the down event that gets generated when a user
* touches the screen. Only that initiates the drag-drop sequence.
*
*/
public boolean onTouch(View v, MotionEvent ev) {
// If we are configured to start only on a long click, we are not going
// to handle any events here.
if (mLongClickStartsDrag)
return false;
boolean handledHere = false;
final int action = ev.getAction();
// In the situation where a long click is not needed to initiate a drag,
// simply start on the down event.
if (action == MotionEvent.ACTION_DOWN) {
handledHere = startDrag(v);
}
return handledHere;
}
/**
* Start dragging a view.
*
*/
public boolean startDrag(View v) {
DragSource dragSource = (DragSource) v;
// We are starting a drag. Let the DragController handle it.
mDragController.startDrag(v, dragSource, dragSource,
DragController.DRAG_ACTION_MOVE);
return true;
}
/**
* Show a string on the screen via Toast.
*
* @param msg
* String
* @return void
*/
public void toast(String msg) {
Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_SHORT).show();
} // end toast
/**
* Send a message to the debug log. Also display it using Toast if Debugging
* is true.
*/
public void trace(String msg) {
Log.d("DragActivity", msg);
if (!Debugging)
return;
toast(msg);
}
} // end class
答案 0 :(得分：0)
我的猜测是它与你使用泛型有关。如果你把它改成
，我会看看你是否能够让它发挥作用public class DragActivity extends Activity implements
View.OnLongClickListener, View.OnClickListener, View.OnTouchListener{
//...
}
您还需要确保在创建后使用Intent。
startActivity(intent);
Switch语句也需要默认选项，如下所示：
switch (pos) {
case 1: //do something
break;
case 2: //do something
break;
default: break;
}