java - Android开发中的精确计算，Java？

Question

我正在为 Android 创建一个计算器，到目前为止它看起来已经完成了......问题是答案并不精确，加法，减法，乘法工作正常，因为通常不需要小数......当它出现时将答案四舍五入为最接近的整数，而不是用小数显示答案...所以我更改了 TextView 类型以显示小数，并使用 float 而不是 int 作为包含答案的变量。结果是我最终得到一个以“.00”结尾的四舍五入整数:/请帮忙!我的代码:主要 Activity .java:

package in.rohanbojja.basiccalculator;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    public void add( View view){

        EditText n1 = (EditText) findViewById(R.id.editText1);
        EditText n2 = (EditText) findViewById(R.id.editText3);
        TextView res = (TextView) findViewById(R.id.textView1);

        String sn1 = n1.getText().toString();
        String sn2 = n2.getText().toString();
        String sres;

        int in1 = Integer.parseInt(sn1);
        int in2 = Integer.parseInt(sn2);
        float ires;

        ires = in1 + in2;
        sres = Float.toString(ires);
        res.setText(sres);
}
public void sub( View view ){

    EditText n1 = (EditText) findViewById(R.id.editText1);
    EditText n2 = (EditText) findViewById(R.id.editText3);
    TextView res = (TextView) findViewById(R.id.textView1);

    String sn1 = n1.getText().toString();
    String sn2 = n2.getText().toString();
    String sres;

    int in1 = Integer.parseInt(sn1);
    int in2 = Integer.parseInt(sn2);
    float ires;

    ires = in1 - in2;
    sres = Float.toString(ires);
    res.setText(sres);
}
public void mul( View view ){

    EditText n1 = (EditText) findViewById(R.id.editText1);
    EditText n2 = (EditText) findViewById(R.id.editText3);
    TextView res = (TextView) findViewById(R.id.textView1);

    String sn1 = n1.getText().toString();
    String sn2 = n2.getText().toString();
    String sres;

    int in1 = Integer.parseInt(sn1);
    int in2 = Integer.parseInt(sn2);
    float ires;

    ires = in1 * in2;
    sres = Float.toString(ires);
    res.setText(sres);

}


public void clr( View view ){

    EditText n1 = (EditText) findViewById(R.id.editText1);
    EditText n2 = (EditText) findViewById(R.id.editText3);
    TextView res = (TextView) findViewById(R.id.textView1);

    n1.setText("");
    n2.setText("");
    res.setText("Result");
}

public void div( View view){
    EditText n1 = (EditText) findViewById(R.id.editText1);
    EditText n2 = (EditText) findViewById(R.id.editText3);
    TextView res = (TextView) findViewById(R.id.textView1);

    String sn1 = n1.getText().toString();
    String sn2 = n2.getText().toString();
    String sres;

    int in1 = Integer.parseInt(sn1);
    int in2 = Integer.parseInt(sn2);
    float ires;

    ires = in1/in2;
    sres = Float.toString(ires);
    res.setText(sres);
}
}

Answer 1

int in1 = Integer.parseInt(sn1);
int in2 = Integer.parseInt(sn2);
float ires;

ires = in1/in2;

您仍在进行整数除法，只是将结果存储在 float 中。要执行浮点除法，in1 和 in2 必须是 float 。