Question

因此，我尝试在我的主要活动中使用fragment从另一个fragment填充一个button。主要活动是fragments的父级。布局看起来像这样

fragMoney包含需要设置的TextViews

fragCalculate包含EditText字段，我从中输入设置fragMoney的TextViews和button来计算总数。

父母

MainActivity是我尝试做这项工作的地方。

我收到一条关于null pointer exception的长错误消息，但我似乎无法弄清楚我哪里出错了。我猜想它是因为我没有在某段代码之前声明某些东西。无论如何，这里是代码和logcat。

主要活动按钮

public void calculateHandler(View view) {
    Log.v("*** DEBUG ***", "calc button");
    dailyView.setText("" + getDaily());
    Log.v("*** DEBUG ***", "getting daily");
    monthlyView.setText("" + getMonthly());
    Log.v("*** DEBUG ***", "getting month");
    annualView.setText("" + getAnnually());
    Log.v("*** DEBUG ***", "getting year");
    totalView.setText("" + getTotal());     
    Log.v("*** DEBUG ***", "getting total");
}

主要活动方法

public double getDaily() {

    double price = Double.parseDouble(packPrice.getText().toString());      
    double packs = Double.parseDouble(numPacks.getText().toString());

    daily = price * packs;

    return daily;
}

public double getMonthly() {
    double price = Double.parseDouble(packPrice.getText().toString());      
    double packs = Double.parseDouble(numPacks.getText().toString());

    monthly = price * packs * 30.41;

    return monthly;
}

public double getAnnually() {
    double price = Double.parseDouble(packPrice.getText().toString());      
    double packs = Double.parseDouble(numPacks.getText().toString());   

    annually = (price * packs) * 365;

    return annually;
}

public double getTotal () {
    double price = Double.parseDouble(packPrice.getText().toString());      
    double packs = Double.parseDouble(numPacks.getText().toString());
    double years = Double.parseDouble(numYears.getText().toString());

    total = (price * packs) * 365 * years;      

    return total;
}

logcat的

03-30 16:27:43.443: E/AndroidRuntime(815): FATAL EXCEPTION: main
03-30 16:27:43.443: E/AndroidRuntime(815): java.lang.IllegalStateException: Could not execute method of the activity
03-30 16:27:43.443: E/AndroidRuntime(815):  at android.view.View$1.onClick(View.java:3591)
03-30 16:27:43.443: E/AndroidRuntime(815):  at android.view.View.performClick(View.java:4084)
03-30 16:27:43.443: E/AndroidRuntime(815):  at android.view.View$PerformClick.run(View.java:16966)
03-30 16:27:43.443: E/AndroidRuntime(815):  at android.os.Handler.handleCallback(Handler.java:615)
03-30 16:27:43.443: E/AndroidRuntime(815):  at android.os.Handler.dispatchMessage(Handler.java:92)
03-30 16:27:43.443: E/AndroidRuntime(815):  at android.os.Looper.loop(Looper.java:137)
03-30 16:27:43.443: E/AndroidRuntime(815):  at android.app.ActivityThread.main(ActivityThread.java:4745)
03-30 16:27:43.443: E/AndroidRuntime(815):  at java.lang.reflect.Method.invokeNative(Native Method)
03-30 16:27:43.443: E/AndroidRuntime(815):  at java.lang.reflect.Method.invoke(Method.java:511)
03-30 16:27:43.443: E/AndroidRuntime(815):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
03-30 16:27:43.443: E/AndroidRuntime(815):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-30 16:27:43.443: E/AndroidRuntime(815):  at dalvik.system.NativeStart.main(Native Method)
03-30 16:27:43.443: E/AndroidRuntime(815): Caused by: java.lang.reflect.InvocationTargetException
03-30 16:27:43.443: E/AndroidRuntime(815):  at java.lang.reflect.Method.invokeNative(Native Method)
03-30 16:27:43.443: E/AndroidRuntime(815):  at java.lang.reflect.Method.invoke(Method.java:511)
03-30 16:27:43.443: E/AndroidRuntime(815):  at android.view.View$1.onClick(View.java:3586)
03-30 16:27:43.443: E/AndroidRuntime(815):  ... 11 more
03-30 16:27:43.443: E/AndroidRuntime(815): Caused by: java.lang.NullPointerException
03-30 16:27:43.443: E/AndroidRuntime(815):  at com.example.smokin4tomsullivan.MainActivity.getDaily(MainActivity.java:162)
03-30 16:27:43.443: E/AndroidRuntime(815):  at com.example.smokin4tomsullivan.MainActivity.calculateHandler(MainActivity.java:199)
03-30 16:27:43.443: E/AndroidRuntime(815):  ... 14 more

一如既往地感谢大家给予的任何帮助

更新说明

好的，所以在调试后出现这行代码：

double price = Double.parseDouble(packPrice.getText().toString()); 给我带来麻烦。 EditText集合中的CalcFrag字段采用类型numDecimals，在此次运行中我输入了8.7 有什么想法吗？

第二次更新 这是初始化packPrice的代码，它在onCreate

中

EditText packPrice = (EditText) findViewById(R.id.per_pack_Id);

第三次更新 这是我用log.v运行的代码，也见上面修改过的calcButton

public double getDaily() {
    Log.v("*** DEBUG ***", "running getDaily");
    EditText packPrice = (EditText) findViewById(R.id.per_pack_Id);
    Log.v("*** DEBUG ***", "initialized packPrice");
    double price = Double.parseDouble(packPrice.getText().toString());
    Log.v("*** DEBUG ***", packPrice.getText().toString());
    String test = ("" + price);
    Log.v("*** DEBUG ***", test);
    double packs = Double.parseDouble(numPacks.getText().toString());
    String test1 = ("" + packs);
    Log.v("*** DEBUG ***", test1);

    daily = price * packs;

    return daily;
}

当我在崩溃之前运行它时，log.v吐出了这个

03-30 17:34:15.883: V/*** DEBUG ***(1166): calc button
03-30 17:34:15.883: V/*** DEBUG ***(1166): running getDaily
03-30 17:34:15.893: V/*** DEBUG ***(1166): initialized packPrice
03-30 17:34:15.893: V/*** DEBUG ***(1166): 9.9 <-- the values I entered
03-30 17:34:15.893: V/*** DEBUG ***(1166): 9.9 <-- the values I entered

Answer 1

异常似乎很明显，packPrice或numPacks为空，或getText的回复在getDaily方法中为空。

您需要确定调用的哪个部分实际上是空的，然后从那里开始工作。

来自MainActivity Android的Fragment中的setText

1 个答案: