Is there a way to pass a string variable to a for loop in Java?-CodePudding

My requirement is to delete data from a database, but the strings I need to pass to the DELETE query are dynamically generated, so I have to first collect the data and then use it in a for loop that would send the DELETE query multiple times.

My steps so far:

First, I filtered a list so as to collect a list of required elements into a variable. I got the expected output:

List<String> newFilter = allProductNames.stream().filter(field -> field.startsWith("sample", 1)).collect(Collectors.toList());
System.out.println(newFilter)

Output:

"sample1", "sample2", "sample3", "sample4"

Now, I want to use each of the elements to send a query to a Neo4j database, using the query - DROP DATABASE <database_name> wait; where <database_name> would be replaced by each of my collected elements. So the queries will look like this:

DROP DATABASE sample1 wait;
DROP DATABASE sample2 wait;
DROP DATABASE sample3 wait;
DROP DATABASE sample4 wait;
DROP DATABASE sample5 wait;

What comes straight to my mind is that a for loop can help me to send the query repeatedly by passing sample1 in the first query, sample2 in the second query...and so on, but my dilemma is that I am lost on how to achieve this.

I tried something like this, but it wont work:

List<String> newFilter = allProductNames.stream().filter(field -> field.startsWith("sample", 1)).collect(Collectors.toList());

    int filterSize = newFilter.size();

    int i = 0;
    String dropDatabase = "DROP DATABASE "   i   " wait;"; //i want to pass the element as a variable here

    for (; i < filterSize ; i  ) {

      basePage.queryInputField.sendKeys(dropDatabase);
    }

What I was trying to do in the loop is to pass make i = sample1 in the first run, i = sample2 in the second run and so on, but i is an int and I believe only an int can be passed into a condition as far as my little Java knowledge.

How can I pass the String sample1 to the loop in the first run to achieve this - DROP DATABASE sample1 wait; and pass the other elements in subsequent runs? I am open to any other approach than can help me achieve this.

CodePudding user response：

It does not work because you are not updating the dropDatabase String at any moment in the loop.

You have two options, use a for each or a for i updating the string:

for (int i = 0; i < filterSize; i  ) {
    basePage.queryInputField.sendKeys("DROP DATABASE "   newFilter.get(i)   " wait;");
}


for (String database : newFilter) {
    basePage.queryInputField.sendKeys("DROP DATABASE "   database   " wait;");
}

Or if you want the query string apart you could also use a format like this:

String format = "DROP DATABASE %s wait;";
for (String database : newFilter) {
    basePage.queryInputField.sendKeys(String.format(format, database));
}

CodePudding user response：

Try this:

for (String dbName : newFilter) {
    String dropDatabase = "DROP DATABASE "   dbName   " wait;";
    basePage.queryInputField.sendKeys(dropDatabase);
}