对话框AlertDialog的dismiss和cancel区别

  /**
     * Cancel the dialog.  This is essentially the same as calling {@link #dismiss()}, but it will
     * also call your {@link DialogInterface.OnCancelListener} (if registered).
     */
    public void cancel() {
        if (!mCanceled && mCancelMessage != null) {
            mCanceled = true;
            // Obtain a new message so this dialog can be re-used
            Message.obtain(mCancelMessage).sendToTarget();
        }
        dismiss();
    }

public void openDialog(View v){
        AlertDialog dialog ;
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("标题");
        builder.setMessage("dismiss和cancel的区别");
        builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
            
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.cancel();
            }
        });
        
        builder.setNegativeButton("取消",new DialogInterface.OnClickListener() {
            
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        
        dialog = builder.create();
        dialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
            @Override
            public void onCancel(DialogInterface dialog) {
                Toast.makeText(MainActivity.this, "setOnCancelListener", Toast.LENGTH_SHORT).show();
            }
        });
        dialog.show();
    }