Android的spinner获取索引和设置显示第几项

 //选择业务类型的下拉
    Spinner mSpinner;
 //业务类型下拉
    void businessTypeSelect() {
        String[] arr = {"门店要货", "门店退货", "店间调货"};
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, arr) {
        };
        mSpinner = findViewById(R.id.spinner_businessType_allocationList);
        mSpinner.setAdapter(adapter);

        mSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                //获取下拉的索引
                if (mSpinner.getSelectedItemPosition() == 0) {
                    Toast.makeText(getBaseContext(), "你选中的选项为" + mSpinner.getSelectedItemPosition(), Toast.LENGTH_SHORT).show();

                } else if (mSpinner.getSelectedItemPosition() == 1) {
                    Toast.makeText(getBaseContext(), "你选中的选项为" + mSpinner.getSelectedItemPosition(), Toast.LENGTH_SHORT).show();

                } else if (mSpinner.getSelectedItemPosition() == 2) {
                    Toast.makeText(getBaseContext(), "你选中的选项为" + mSpinner.getSelectedItemPosition(), Toast.LENGTH_SHORT).show();
                }
//设置显示的的某一项来显示
mSpinner.setSelection(2);//显示第三项来显示
 mSpinner.setSelection(0);//显示第二项来显示
 mSpinner.setSelection(1);//显示第一项来显示
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });
    }