我在自己的公共类中有三种静态方法。简单的算术方法可以帮助我学习。
这些方法使用三个变量，这些变量在主方法中定义为静态int变量。该程序有效。
现在，根据对已阅读内容的理解，我应该能够将变量定义移至另一个类并将其定义为public。然后，其自己的公共类中的main方法应该能够找到这些定义并运行。但这不会发生。相反，我的Eclipse工作区报告无法将定义解析为变量。
这是非常简单的代码（这给了我编译错误）：
package christmas;
public class addintegers {
public int number1 = 5;
public int number2 = 10;
public int answer;
public static int add2numbers(int a, int b) {
return (a + b);
}
}
第2类
package christmas;
public class subtractintegers {
public static int sub2numbers(int a, int b) {
return (a - b);
}
}
然后我有我的主要方法。这是我收到编译错误的地方。
package christmas;
public class glue {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println(addintegers.add2numbers(number1, number2));
System.out.println(subtractintegers.sub2numbers(number1, number2));
answer = (addintegers.add2numbers(number1, number2)) + (subtractintegers.sub2numbers(number1, number2));
System.out.println("answer =" + answer);
}
}
我得到的错误是：
>create local variable number1
>create local variable number2
>create local variable answer
答案 0 :(得分：0)
首先，
例如，类似以下内容的东西：
public class Addition {
public static int add(int a, int b) {
return a + b;
}
}
public class Subtraction {
public static int subtract(int a, int b) {
return a - b;
}
}
如果您想在我重命名为number1的类中拥有number2，answer和Addition字段，通常您要做的就是将它们设为{{1 }}实例变量，并通过getter公开它们：
private然后您可以通过创建该类的实例来访问它们，例如：public class Addition {
private int number1 = 5;
public int getNumber1() {
return number1;
}
}
。由于new Addition().getNumber1();和Addition类似乎是 utility类，因此声明这些字段Subtraction也许更有意义，因此您不必实例化课程：
private static然后您可以通过引用该类而不是该类的实例（例如：public class Addition {
private static int number1 = 5;
public static int getNumber1() {
return number1;
}
}
）来访问它们。
答案 1 :(得分：-1)
您快到了。您缺少2个关键点：
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
<div class="modal-body predefineModal">
<div class="bs-example">
<div id="myCarousel" class="carousel slide">
<!-- Carousel indicators -->
<ol class="carousel-indicators">
<li data-target="#myCarousel" data-slide-to="0" class="active"></li>
<li data-target="#myCarousel" data-slide-to="1"></li>
</ol>
<!-- Wrapper for carousel items -->
<div class="carousel-inner">
<div class="carousel-item active">
<div class="table-responsive">
<table class="table table-bordered">
<thead class="party_head">
<tr>
<th>#</th>
<th>S.No</th>
<th>Trans.Type</th>
<th>Voucher Date</th>
<th>To A/c Name</th>
<th>Narration</th>
<th>Debit</th>
<th>Credit</th>
</tr>
</thead>
<tbody>
<tr class="line-content">
<td><input id="indeterminate-checkbox" type="checkbox" /></td>
<td>1</td>
<td>CP</td>
<td>DD-MM-YYYY</td>
<td>JOE</td>
<td>Narration</td>
<td>Debit</td>
<td>Credit</td>
</tr>
<tr class="line-content">
<td>
<input type="checkbox" id="indeterminate-checkbox"/>
</td>
<td>2</td>
<td>BP</td>
<td>DD-MM-YYYY</td>
<td>PLUMZ</td>
<td>Narration</td>
<td>Debit</td>
<td>Credit</td>
</tr>
<tr class="line-content">
<td><input id="indeterminate-checkbox" type="checkbox" /></td>
<td>3</td>
<td>CR</td>
<td>DD-MM-YYYY</td>
<td>text</td>
<td>Narration</td>
<td>Debit</td>
<td>Credit</td>
</tr>
<tr class="line-content">
<td><input id="indeterminate-checkbox" type="checkbox" /></td>
<td>4</td>
<td>CR</td>
<td>DD-MM-YYYY</td>
<td>text</td>
<td>Narration</td>
<td>Debit</td>
<td>Credit</td>
</tr>
<tr class="line-content">
<td><input id="indeterminate-checkbox" type="checkbox" /></td>
<td>5</td>
<td>CR</td>
<td>DD-MM-YYYY</td>
<td>text</td>
<td>Narration</td>
<td>Debit</td>
<td>Credit</td>
</tr>
<tr class="line-content">
<td><input id="indeterminate-checkbox" type="checkbox" /></td>
<td>6</td>
<td>CR</td>
<td>DD-MM-YYYY</td>
<td>text</td>
<td>Narration</td>
<td>Debit</td>
<td>Credit</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
<!-- Carousel controls -->
<ul id="pagin"><a class="carousel-control-prev" data-slide="prev">
<span class="carousel-control-prev-icon"></span>
</a>
<a class="carousel-control-next" data-slide="next">
<span class="carousel-control-next-icon"></span>
</a></ul>
</div>
</div>
</div> package christmas;
public class addintegers {
public static int number1 = 5;
public static int number2 = 10;
public static int answer;
public static int add2numbers(int a, int b) {
return (a+b);
}
}
答案 2 :(得分：-2)
df['column'] = None #This works. This will create a new column with None type
df.column = None #This will work only when the column is already present in the dataframe