Question

如果有其他简单方法可以优化/实现以下可能性的代码，请帮助我。 home，bill，reg等变量可以是空字符串（＆＃34;＆＃34;），也可以为null，具体取决于方案。

我的代码

public void helloWorld()
{
    List items=new ArrayList();
    items.add("1"); // dummy list
    String home=""; // can be null or empty
    String bill=null;  // can be null or empty
    String reg="";  // can be null or empty
    if(!items.isEmpty())
    {
        System.out.println("List is not null");
        if(home==null&&bill==null&&reg==null) 
        {
            System.out.println("home is null");
            System.out.println("bill is null");
            System.out.println("reg is null");
        }
        if(home==null&&bill==null&&reg!=null)
        {
            System.out.println("home is null");
            System.out.println("bill is null");
            System.out.println("reg is not null");
        }
        if(home==null&&bill!=null&&reg==null)
        {
            System.out.println("home is null");
            System.out.println("bill is not null");
            System.out.println("reg is null");
        }
        if(home==null&&bill!=null&&reg!=null)
        {
            System.out.println("home is null");
            System.out.println("bill is not null");
            System.out.println("reg is not null");
        }
        if(home!=null&&bill==null&&reg==null)
        {
            System.out.println("home is not null");
            System.out.println("bill is null");
            System.out.println("reg is null");
        }
        if(home!=null&&bill==null&&reg!=null)
        {
            System.out.println("home is not null");
            System.out.println("bill is null");
            System.out.println("reg is not null");
        }
        if(home!=null&&bill!=null&&reg==null)
        {
            System.out.println("home is not null");
            System.out.println("bill is not null");
            System.out.println("reg is null");
        }
        if(home!=null&&bill!=null&&reg!=null)
        {
            System.out.println("home is not null");
            System.out.println("bill is not null");
            System.out.println("reg is not null");
        }
    }
    else
    {
        System.out.println("List is null");
    }
}

请指教。提前谢谢。

Answer 1

只需单独检查home，bill和reg，因为它们之间没有任何依赖关系。

public void helloWorld()
{
    List items=new ArrayList();
    items.add("1"); // dummy list
    String home=""; // can be null or empty
    String bill=null;  // can be null or empty
    String reg="";  // can be null or empty
    if(!items.isEmpty())
    {
        System.out.println("List is not null");
        System.out.println( home == null ? "home is null" : "home is not null" );
        System.out.println( bill == null ? "bill is null" : "bill is not null" );
        System.out.println( reg == null ? "reg is null" : "reg is not null" );

    }
    else
    {
        System.out.println("List is null");
    }
}

Answer 2

建议只检查每个变量而不是列出所有排列

    if(home==null) 
    {
        System.out.println("home is null");
    }
    else
    {
        System.out.println("home is not null");
    }
    if (bill==null)
    {
        System.out.println("bill is null");
    }
    else
    {
        System.out.println("bill is not null");
    }
    ...

Answer 3

根据您对其他答案的评论，您需要采取一些行动......

以下是一个示例，说明如何根据不同字符串的值重用代码来执行不同的操作：

public void helloWorld() {
    List items = new ArrayList();
    items.add("1"); // dummy list
    String home = ""; // can be null or empty
    String bill = null; // can be null or empty
    String reg = ""; // can be null or empty


    switch (validateInputString(home)) {
    case 1:
        //doAction 1;
        break;
    case 2:
        //doAction 2;
        break;
    case 3:
        //doAction 3;
        break;

    default:
        break;
    }

}

public int validateInputString(String toValidate){
    if(toValidate==null)
        return 1;

    if(toValidate.equals(""))
        return 2;


    return 3;
}

你可以为每个字符串执行此操作，并为列表提供类似的内容...

Java条件代码优化

3 个答案: