Delete everything after part of a string

问题:

I have a string that is built out of three parts. The word I want the string to be (changes), a seperating part (doesn't change) and the last part which changes. I want to delete the seperating part and the ending part. The seperating part is " - " so what I'm wondering is if theres a way to delete everything after a certaint part of the string.

An example of this scenario would be if I wanted to turn this: "Stack Overflow - A place to ask stuff" into this: "Stack Overflow". Any help is appreciated!

回答1:

For example, you could do:

String result = input.split("-")[0];

or

String result = input.substring(0, input.indexOf("-"));

(and add relevant error handling)

回答2:

The apache commons StringUtils provide a substringBefore method

StringUtils.substringBefore("Stack Overflow - A place to ask stuff", " - ")

回答3:

You can use this

String substr = mysourcestring.substring(0,mysourcestring.indexOf("-"));

回答4:

Perhaps thats what you are looking for:

String str="Stack Overflow - A place to ask stuff";

String newStr = str.substring(0, str.indexOf("-"));

回答5:

I created Sample program for all the approches and SubString seems to be fastest one.

Using builder : 54
Using Split : 252
Using Substring  : 10

Below is the sample program code

            for (int count = 0; count < 1000; count++) {
        // For JIT
    }
    long start = System.nanoTime();
    //Builder
    StringBuilder builder = new StringBuilder(
            "Stack Overflow - A place to ask stuff");
    builder.delete(builder.indexOf("-"), builder.length());
    System.out.println("Using builder : " + (System.nanoTime() - start)
            / 1000);
    start = System.nanoTime();
    //Split
    String string = "Stack Overflow - A place to ask stuff";
    string.split("-");
    System.out.println("Using Split : " + (System.nanoTime() - start)
            / 1000);
    //SubString
    start = System.nanoTime();
    String string1 = "Stack Overflow - A place to ask stuff";
    string1.substring(0, string1.indexOf("-"));
    System.out.println("Using Substring : " + (System.nanoTime() - start)
            / 1000);
    return null;

回答6:

This will do what you need:

newValue = oldValue.substring(0, oldValue.indexOf("-");

回答7:

String line = "deltaasm:/u01/app/oracle/product/11.2.0/dbhome_1:N        # line addred by agent";

    String rep = "deltaasm:";
    String after = "";

    String pre = ":N";
    String aft = "";
    String result = line.replaceAll(rep, after);
    String finalresult = result.replaceAll(pre, aft);
    System.out.println("Result***************" + finalresult);

    String str = "deltaasm:/u01/app/oracle/product/11.2.0/dbhome_1:N        # line addred by agent";

    String newStr = str.substring(0, str.indexOf("#"));
    System.out.println("======" + newStr);

回答8:

you can my utils method this action..

public static String makeTwoPart(String data, String cutAfterThisWord){
    String result = "";

    String val1 = data.substring(0, data.indexOf(cutAfterThisWord));

    String va12 = data.substring(val1.length(), data.length());

    String secondWord = va12.replace(cutAfterThisWord, "");

    Log.d("VAL_2", secondWord);

    String firstWord = data.replace(secondWord, "");

    Log.d("VAL_1", firstWord);

    result = firstWord + "\n" + secondWord;


    return result;
}`

回答9:

Clean way to safely remove until a string, and keep the searched part if token may or may not exist.

String input = "Stack Overflow - A place to ask stuff";
String token = " - ";
String result = input.contains(token)
  ? token + StringUtils.substringBefore(string, token)
  : input;
// Returns "Stack Overflow - "

Apache StringUtils functions are null-, empty-, and no match- safe

回答10:

Kotlin Solution

Use the built-in Kotlin substringBefore function (Documentation):

var string = "So much text - no - more"
string = string.substringBefore(" - ") // "So much text"

It also has an optional second param, which is the return value if the delimiter is not found. The default value is the original string

string.substringBefore(" - ", "fail")  // "So much text"
string.substringBefore(" -- ", "fail") // "fail"
string.substringBefore(" -- ")         // "So much text - no - more"