Question

我有一个简单的Android应用程序来执行一些计算。虽然文件中没有错误并且构建成功运行，但应用程序崩溃了。

我正在使用Android Studio 3.1，并在Android API 23上测试此应用程序。

我的代码：（见更新）

我的XML：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <Button
        android:id="@+id/calculate_flight_time"
        android:layout_width="276dp"
        android:layout_height="71dp"
        android:layout_marginBottom="96dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:text="Calculate Flight Time"
        android:textSize="18sp"
        android:onClick="calculateFT"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.54"
        app:layout_constraintStart_toStartOf="parent" />

    <Spinner
        android:id="@+id/droneType"
        android:layout_width="245dp"
        android:layout_height="44dp"
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="12dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="319dp"
        android:layout_height="51dp"
        android:layout_marginBottom="30dp"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:gravity="center"
        android:text="This app intends to help drone pilots compute/predict their UAV's flight time beforehand, providing a better insight into prospective builds"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.578"
        app:layout_constraintStart_toStartOf="parent" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:text="By Shlok Jhawar"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

    <EditText
        android:id="@+id/batteryCapacity"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:ems="10"
        android:inputType="number"
        android:hint="Battery Capacity (mAh)"
        android:text="3000"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/droneType" />

    <EditText
        android:id="@+id/MAPM"
        android:layout_width="wrap_content"
        android:layout_height="43dp"
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="20"
        android:ems="10"
        android:hint="Max amps per motor"
        android:inputType="number"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/batteryCapacity" />

    <EditText
        android:id="@+id/MTPM"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:ems="10"
        android:hint="Max thrust per motor (g)"
        android:text="900"
        android:inputType="number"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/MAPM" />

    <EditText
        android:id="@+id/droneWeight"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:ems="10"
        android:hint="Weight of drone"
        android:text="1800"
        android:inputType="number"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/MTPM" />


</android.support.constraint.ConstraintLayout>

我不确定为什么会这样。任何形式的帮助将不胜感激。

更新：领先一步，我的代码不会崩溃。（感谢Manishoaham和Faysal）。做了一些其他的调整。 但是现在，time_in_seconds评估为无穷大，我无法弄明白。请帮忙。这是我的新代码：

package com.example.android.uavuptimecalculator;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
//import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    int number_of_rotors;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Spinner typeOfDrone = (Spinner) findViewById(R.id.droneType);

        ArrayAdapter<String> myAdapter = new ArrayAdapter<String>(MainActivity.this,
                android.R.layout.simple_list_item_1, getResources().getStringArray(R.array.types));
        myAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        typeOfDrone.setAdapter(myAdapter);
        typeOfDrone.setSelection(1);

        String drone_type = typeOfDrone.getSelectedItem().toString();
        if (drone_type=="Tricopter") {
            number_of_rotors=3;
        }
        if (drone_type=="Quadcopter") {
            number_of_rotors=4;
        }
        if (drone_type=="Hexacopter") {
            number_of_rotors=6;
        }
        if (drone_type=="Octacopter") {
            number_of_rotors=8;
        }
        EditText Battery_Capacity = (EditText) findViewById(R.id.batteryCapacity);
        String stringA  = Battery_Capacity.getText().toString();
        EditText Amps_perMotor = (EditText) findViewById(R.id.MAPM);
        String stringB = Amps_perMotor.getText().toString();
        EditText Thrust_perMotor = (EditText) findViewById(R.id.MTPM);
        String stringC = Thrust_perMotor.getText().toString();
        EditText Weight_ofDrone = (EditText) findViewById(R.id.droneWeight);
        String stringD = Weight_ofDrone.getText().toString();
        int battery_capacity_mah =Integer.parseInt(stringA!=null&&!stringA.isEmpty()?stringA:"0");
        //int battery_capacity_mah = Integer.parseInt(Battery_Capacity.toString());
        //int total_max_ampdraw = Integer.parseInt(Amps_perMotor.toString()) * number_of_rotors;
        int total_max_ampdraw = Integer.parseInt(stringB!=null&&!stringB.isEmpty()?stringB:"0") * number_of_rotors;
        //int total_thrust = Integer.parseInt(Thrust_perMotor.toString()) * number_of_rotors;
        int total_thrust =  Integer.parseInt(stringC!=null&&!stringC.isEmpty()?stringC:"0") * number_of_rotors;
        //float required_throttle = Integer.parseInt(Weight_ofDrone.toString()) / total_thrust;
        float required_throttle = Integer.parseInt(stringD!=null&&!stringD.isEmpty()?stringD:"0") * number_of_rotors;
        /*if (required_throttle>=1){
            Toast.makeText(MainActivity.this,"UAV will not take off",Toast.LENGTH_SHORT);
        }*/
        float avg_ampdraw=required_throttle*total_max_ampdraw;

        String abc = Float.toString(avg_ampdraw);
        Toast.makeText(MainActivity.this,abc,Toast.LENGTH_SHORT);
        //Toast.makeText(MainActivity.this,avg_ampdraw,Toast.LENGTH_SHORT);
        float battery_capacity_ah=battery_capacity_mah/1000;
        float time_in_hours=battery_capacity_ah/avg_ampdraw;
        final float time_in_minutes=time_in_hours*60;
        final float time_in_seconds=time_in_minutes*60;
        //public void calculateFT()
        Button CalculateFTime = (Button) findViewById(R.id.calculate_flight_time);
        CalculateFTime.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                AlertDialog.Builder mBuilder = new AlertDialog.Builder(MainActivity.this);
                mBuilder.setTitle("Calculated Flight Time");
                //mBuilder.setTitle(R.string.dialog_title);
                mBuilder.setMessage("Your UAV will fly for "+time_in_seconds+" seconds, which is equivalent to "+time_in_minutes+" minutes");
                mBuilder.setNeutralButton("OK", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
                });

                AlertDialog alertDialog = mBuilder.create();
                alertDialog.show();
            }
        });



    }


}

所有帮助将不胜感激。

Answer 1

从EditText获取文本有一些问题。要从EditText获取文本，请使用以下行：

String string = yourEditText.getText().toString();

您需要在getText()之前添加toString()才能获取文字。

int battery_capacity_mah = Integer.parseInt(Battery_Capacity.getText().toString());
int total_max_ampdraw = Integer.parseInt(Amps_perMotor.getText().toString()) * number_of_rotors;
int total_thrust = Integer.parseInt(Thrust_perMotor.getText().toString()) * number_of_rotors;
float required_throttle = Integer.parseInt(Weight_ofDrone.getText().toString()) / total_thrust;

希望这会有所帮助。

Answer 2

首先从您的editText获取文字：

kind

其次，由于您已经将inputStyle定义为数字，因此您只会获得可解析的数字字符串，但也会检查您是否获得空字符串，如下所示

String string = Battery_Capacity.getText().toString();

同样适用于所有其他editTexts。

尝试使用此代码：

int battery_capacity_ham = Integer.parseInt(string!=null&&!string.isEmpty()?string:"0");

尽管代码中没有错误，但简单计算目的应用程序崩溃了

2 个答案: