问题描述
所以我一直在尝试在 android studio 上运行一个简单的计算器应用程序，但它一直崩溃。我已经检查了 logcat 和所有文件，但我终其一生都无法弄清楚出了什么问题。任何帮助将非常感激。 如果有帮助，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);
}
}
先谢谢你！
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 ComponentInfo{com.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
解决方法
好吧，您正在为 checkAmountR 中的 checkAmountD、numPeopleD、onCreate() 分配值，这些值最初将分配为空的 String，因此当您解析它抛出 NumberFormatException
将它们移动到 onClick() 内，因此当点击它时，它实际上会从 EditText 中获取值
@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，总是使用tryParse，以避免这种NumberFormatException