为什么在android studio中的小数点可以输出，但是不能运算。

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.SwitchCompat;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
private TextView tvresult;
private Button[] btns;
private double x1;
private double x2;
private double x3;
private Boolean bop=false;
private double iop;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
int
[] myids ={
R.id.btn_zero,
R.id.btn_one,
R.id.btn_two,
R.id.btn_three,
R.id.btn_four,
R.id.btn_five,
R.id.btn_six,
R.id.btn_seven,
R.id.btn_eight,
R.id.btn_nine,
R.id.btn_clear,
R.id.btn_plus,
R.id.btn_minus,
R.id.btn_equal,
R.id.btn_multiply,
R.id.btn_divide,
R.id.ib_sqrt,
R.id.btn_dot

    };
    btns=new Button[myids.length];

    //setContentView(R.layout.activity_main);
    this.setContentView(R.layout.mylayout);
    tvresult=(TextView)this.findViewById(R.id.tv_result);
    tvresult.setText("");
    MyListener myobj=new MyListener();
    for(int i=0;i<btns.length;i++) {
        btns[i] = (Button) this.findViewById( myids[i]);
        btns[i].setOnClickListener(myobj);
    }

}
class MyListener implements View.OnClickListener{

    @Override
    public void onClick(View v) {
        Button mybtn=(Button)v;
       String mytext = tvresult.getText().toString();
        int myid=mybtn.getId();
        switch ( myid) {
            case R.id.btn_clear:
                tvresult.setText("");
                bop=false;
                break;
            case R.id.btn_plus:
            case R.id.btn_minus:
            case R.id.btn_multiply:
            case R.id.btn_divide:
            case R.id.ib_sqrt:
                iop=myid;
                bop=true;
                if(mytext.equals(""))
                    x1=0;
                else
                    x1=Integer.parseInt( mytext);
                break;
            case R.id.btn_equal:
                if(mytext.equals(""))
                    x2=0;
                else
                    x2=Integer.parseInt( mytext);
                if(iop==R.id.btn_plus) {
                    x1=x1+x2;
                }
                else if(iop==R.id.btn_minus)
                {
                    x1=x1-x2;
                }
                else if(iop==R.id.btn_multiply)
                {
                    x1=(x1*x2);}
                else if(iop==R.id.btn_divide){x1=(x1/x2);

            }
                else if(iop==R.id.ib_sqrt){
                    x1=Math.sqrt(x1);
                }
                tvresult.setText(x1+"");
                break;
            default:
                if(bop) {
                    mytext = "";
                    bop=false;
                }
                tvresult.setText(mytext + mybtn.getText());
                break;
        }
    }
}

你这个不能运算是什么意思