检查整数值是否增加？

发布于 2024-12-02 10:33:28 字数 358 浏览 0 评论 0原文

我有以下代码，用于检查数据库中的行数。

private void checkMMSRows(){
    Cursor curPdu = getContentResolver().query(Uri.parse("content://mms/part"), null, null, null, null);
    if (curPdu.moveToNext()){
        int number = curPdu.getCount();
        System.out.println(number);
    }
}

我将每秒运行此代码并在值发生变化时执行某些操作。问题是，我如何去“检测”变化？任何帮助将不胜感激。

原文

I have the following code, which checks for the number of rows in the database.

private void checkMMSRows(){
    Cursor curPdu = getContentResolver().query(Uri.parse("content://mms/part"), null, null, null, null);
    if (curPdu.moveToNext()){
        int number = curPdu.getCount();
        System.out.println(number);
    }
}

I will to run this code every second and do something when the value has changed. The problems is, how do I go about "detecting" the change? Any help would be appreciated.

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荒人说梦 2024-12-09 10:33:28

基本上，添加一个类变量 - 您可以将其设置为该类的所有实例的静态变量，也可以将其设置为实例变量（通过删除静态关键字）。

每次获得一个数字时，您都可以将其与oldNumber进行比较。比较后，将 oldNumber 设置为当前数字 - 这样您下次就有了可比较的内容：

private static int oldNumber = -1;
private void checkMMSRows(){
    Cursor curPdu = getContentResolver().query(Uri.parse("content://mms/part"), null, null, null, null);
    if (curPdu.moveToNext()){
        int number = curPdu.getCount();
        System.out.println(number);
        if(number != oldNumber){
            System.out.println("Changed");
            // add any code here that you want to react to the change
        }
        oldNumber = number;
    }
}

更新：

我的答案是直接代码 hack &斜杠解决方案，但我可能会推荐amit的答案。

Very basically, add a class variable - you can either make it static across all instances of the class, or an instance variable (by removing the static keyword).

Each time you get a number, you can compare it to oldNumber. After the comparison, set the oldNumber to the current number - so you have something to compare against next time:

private static int oldNumber = -1;
private void checkMMSRows(){
    Cursor curPdu = getContentResolver().query(Uri.parse("content://mms/part"), null, null, null, null);
    if (curPdu.moveToNext()){
        int number = curPdu.getCount();
        System.out.println(number);
        if(number != oldNumber){
            System.out.println("Changed");
            // add any code here that you want to react to the change
        }
        oldNumber = number;
    }
}

Update:

My answer's a straight code hack & slash solution, but I'd probably recommend amit's answer.

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姐不稀罕 2024-12-09 10:33:28

取决于运行的上下文。
假设该方法所属的对象在不同的检查之间存在，您需要做的就是向该对象添加一个 int currentValue 字段，将第一次检查时的值存储在那里，然后将该值与存储的值进行比较在后续检查中（并在必要时更新）

int currentValue = 0;
private void checkMMSRows(){
    Cursor curPdu = getContentResolver().query(Uri.parse("content://mms/part"), null, null, null, null);
    if (curPdu.moveToNext()){
        int newValue = curPdu.getCount();
        if (newvalue != currentValue) {
               //detected a change
               currentValue = newValue;
        }
        System.out.println(newValue);
    }
}

Depends on the context in which this is run.
Assuming that the Object which this method belongs to will live between different checks, all you need to do is to add a int currentValue field to the object, store the value in there first time you check, and then compare the value with the stored ones in subsequent checks (and update if necessary)

int currentValue = 0;
private void checkMMSRows(){
    Cursor curPdu = getContentResolver().query(Uri.parse("content://mms/part"), null, null, null, null);
    if (curPdu.moveToNext()){
        int newValue = curPdu.getCount();
        if (newvalue != currentValue) {
               //detected a change
               currentValue = newValue;
        }
        System.out.println(newValue);
    }
}

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