public void onClick(View view){
        int id=view.getId();
        switch (id){
            case R.id.btnResult:
                if(edWeight.length()==0 || edHeight.length()==0){
                    Toast.makeText(MainActivity.this,"輸入數字",Toast.LENGTH_LONG).show();
                    return;
                }
                double height=Double.parseDouble(edHeight.getText().toString());
                double weight=Double.parseDouble(edWeight.getText().toString());

                Intent intent=new Intent(MainActivity.this,ResultActivity.class);
                Bundle bundle=new Bundle();
                bundle.putDouble("height",height);
                bundle.putDouble("weight",weight);
                intent.putExtras(bundle);
                //只傳送資料
                //startActivity(intent);

                //傳送資料並準備接受回傳資料
                startActivityForResult(intent,BMI_REQUEST_CODE);

                break;
            case R.id.btnCls:
                edHeight.setText("");
                edWeight.setText("");
                edHeight.requestFocus();

                ivResult.setVisibility(View.GONE);//讓預設藏起來的圖片也不見
                break;
        }

    }