Android Studio 中的简单计算器应用程序不断关闭

Posted 2023-02-24

【中文标题】Android Studio 中的简单计算器应用程序不断关闭

【英文标题】：Simple calculator app in Android studio keeps closing

【发布时间】：2021-02-18 12:55:40

【问题描述】：

所以我一直试图在 android studio 上运行一个简单的计算器应用程序，但它一直在崩溃。我已经检查了 logcat 和所有文件，但我仍然无法找出问题所在。任何帮助将非常感激。 如果有帮助的话，我也可以在这里添加 logcat！ 这是我的 XML 代码：

我的java代码：

public class Assignment_01 extends Activity 

    private Button btnGo;
    private EditText checkAmount, numOfPeople;
    private double tip = 0.15;
    double checkAmountD, checkAmountR;
    double numPeopleD;
    private TextView viewBill, viewPerson, viewTip;
    double totalB, totalP, totalTP, totalT;

    /** hi */
    @Override
    public void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_linearlayout);

        // get info from text box called checkAmount:

        checkAmount = (EditText) findViewById(R.id.checkAmount);
        String checkString = checkAmount.getText().toString();
        checkAmountD = Double.parseDouble(checkString);
        checkAmountR = Math.round(checkAmountD * 100.0) / 100.0;

        // get info from number of people

        numOfPeople = (EditText) findViewById(R.id.numOfPeople);
        String numPeopleS = numOfPeople.getText().toString();
        numPeopleD = Double.parseDouble(numPeopleS);

        // if button is clicked, calculate other 4 values and display them

        // button called btnLogin:

        btnGo = (Button) findViewById(R.id.btnGo);
        btnGo.setOnClickListener(  new View.OnClickListener()  // view. ? maybe not

            // once button is clicked (onClick)
            public void onClick(View view) 

                // calculate total tip, total bill, total per person, and total tip per person
                totalT = checkAmountR  * tip;
                totalB = checkAmountR + totalT;
                totalP = totalB / numPeopleD;
                totalTP = totalT / numPeopleD;

                // print these 4 out on the edit texts
                setNewText();

             // on click
        );   // on click listener

    

    public void setNewText()
        // print these 4 out on the edit texts
        TextView viewBill = (TextView) findViewById(R.id.totalBill);
        String totalBillS = String.valueOf(totalB);
        viewBill.setText("$" + totalBillS);
        viewBill.append("$" + totalBillS);

        TextView viewPerson = (TextView) findViewById(R.id.totalPerPerson);
        String totalPerPS = String.valueOf(totalP);
        viewPerson.setText("$" + totalPerPS);
        viewPerson.append("$" + totalPerPS);

        TextView viewTip = (TextView) findViewById(R.id.totalTip);
        String totalTipS = String.valueOf(totalP);
        viewTip.setText("$" + totalTipS);
        viewTip.append("$" + totalTipS);

        TextView viewTipPerPerson = (TextView) findViewById(R.id.tipPerPerson);
        String tipPerPersonS = String.valueOf(totalTP);
        viewTipPerPerson.setText("$" + tipPerPersonS);
        viewTipPerPerson.append("$" + tipPerPersonS);
    

堆栈溢出不允许我添加 XML 代码或 android 清单

提前谢谢你！

这是logcat的前半部分：

2021-02-18 00:27:56.993 3622-3622/? E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.course.example, PID: 3622
    java.lang.RuntimeException: Unable to start activity ComponentInfocom.course.example/com.course.example.LayoutDemo: java.lang.NumberFormatException: empty String
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
     Caused by: java.lang.NumberFormatException: empty String
        at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1842)
        at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
        at java.lang.Double.parseDouble(Double.java:538)
        at com.course.example.LayoutDemo.onCreate(LayoutDemo.java:33)
        at android.app.Activity.performCreate(Activity.java:7802)
        at android.app.Activity.performCreate(Activity.java:7791)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1299)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) 
        at android.os.Handler.dispatchMessage(Handler.java:107) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:7356) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) 
2021-02-18 00:27:57.303 2605-3513/com.google.android.gms.persistent E/ActivityThread: Failed to find provider info for instantapp-dev-manager
2021-02-18 00:27:57.578 1988-2101/system_process E/SupplicantStaIfaceHal: ISupplicantStaIface.setPowerSave failed: .code = FAILURE_UNKNOWN, .debugMessage = 
2021-02-18 00:27:57.601 1728-1953/? E/Netd: no such netId 101
2021-02-18 00:27:57.602 1988-2104/system_process E/ConnectivityService: Exception adding interface: java.lang.IllegalStateException: android.os.ServiceSpecificException: Machine is not on the network (code 64)
2021-02-18 00:27:57.602 1728-1953/? E/Netd: no such netId 101
2021-02-18 00:27:57.638 2605-3811/com.google.android.gms.persistent E/BluetoothAdapter: Bluetooth binder is null
2021-02-18 00:27:57.676 1988-2101/system_process E/SupplicantStaIfaceHal: ISupplicantStaIface.setPowerSave failed: .code = FAILURE_UNKNOWN, .debugMessage = 
2021-02-18 00:27:57.679 1728-2197/? E/Netd: no such netId 101
2021-02-18 00:27:57.679 1988-2104/system_process E/ConnectivityService: Exception in addRoute for non-gateway: java.lang.IllegalStateException: android.os.ServiceSpecificException: Machine is not on the network (code 64)
2021-02-18 00:27:57.679 1728-2197/? E/Netd: no such netId 101

【问题讨论】：

I could add the logcat over here as well if that would help 没有日志，我们猜测如何解决问题，所以是的，您总是需要添加日志。当出现问题时，这些是您应该首先考虑的事情

@a_local_nobody 好的，你会建议用任何特定的东西过滤它吗？它的atm很长

您需要为您的应用找到错误日志，因为这些是您的崩溃，所以是的，在 logcat 中过滤错误并针对所选应用程序

@a_local_nobody 是的，有道理，就这么做了，谢谢

我已经对您发布的堆栈跟踪进行了一些更改，通常您应该寻找E/AndroidRuntime: FATAL EXCEPTION: 或类似的东西，这样您就会知道它从哪里开始。在你的情况下，它说：Caused by: java.lang.NumberFormatException: empty String。现在，如果你知道堆栈跟踪并阅读它们，你可能已经猜到你的代码出了什么问题，对吧:)

【参考方案1】：

好吧，您在onCreate() 中为checkAmountR、checkAmountD、numPeopleD 分配值，最初将分配给空的String，所以当您解析它时会抛出NumberFormatException

将它们移动到onClick() 中，所以当点击它时，它实际上会从EditText 获取值

   @Override
    public void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_linearlayout);
        checkAmount = (EditText) findViewById(R.id.checkAmount);
        numOfPeople = (EditText) findViewById(R.id.numOfPeople);
        btnGo = (Button) findViewById(R.id.btnGo);
        btnGo.setOnClickListener(  new View.OnClickListener()  // view. ? maybe 
            public void onClick(View view) 
                String checkString = checkAmount.getText().toString();
                checkAmountD = Double.parseDouble(checkString);
                checkAmountR = Math.round(checkAmountD * 100.0) / 100.0;
               
                String numPeopleS = numOfPeople.getText().toString();
                numPeopleD = Double.parseDouble(numPeopleS);

                totalT = checkAmountR  * tip;
                totalB = checkAmountR + totalT;
                totalP = totalB / numPeopleD;
                totalTP = totalT / numPeopleD;

                // print these 4 out on the edit texts
                setNewText();

             // on click
        );   // on click listener

    

另外，请始终使用tryParse，以避免这种NumberFormatException