stringbuilder append at index java - Brave Search

java: use StringBuilder to insert at the beginning

stackoverflow.com › questions › 5931261 › java-use-stringbuilder-to-insert-at-the-beginning

// DO NOT DO THIS. It is quadratic-time!
StringBuilder sb = new StringBuilder();
for(int i=0;i<100;i++){
    sb.insert(0, Integer.toString(i));
}

Warning: It defeats the purpose of StringBuilder, but it does what you asked.

Better technique (although still not ideal):

Reverse each string you want to insert.
Append each string to a StringBuilder.
Reverse the entire StringBuilder when you're done.

This will turn an O(n²) solution into O(n).

Answer from user541686 on Stack Overflow

docs.oracle.com › javase › 8 › docs › api › java › lang › StringBuilder.html

StringBuilder (Java Platform SE 8 )

April 21, 2026 - Let n be the length of this character ... Then the character at index k in the new character sequence is equal to the character at index k in the old character sequence, if k is less than n; otherwise, it is equal to the character at index k-n in the argument str....

tutorialspoint.com › java › lang › stringbuilder_append_subsequence.htm

Java.lang.StringBuilder.append() Method

The java.lang.StringBuilder.ap... to this sequence. Characters of the argument s, starting at index start, are appended, in order, to the contents of this sequence up to the (exclusive) index end....

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docs.oracle.com › javase › 7 › docs › api › java › lang › StringBuilder.html

StringBuilder (Java Platform SE 7 )

Let n be the length of this character ... Then the character at index k in the new character sequence is equal to the character at index k in the old character sequence, if k is less than n; otherwise, it is equal to the character at index k-n in the argument str....

stackoverflow.com › questions › 5931261 › java-use-stringbuilder-to-insert-at-the-beginning

string - java: use StringBuilder to insert at the beginning - Stack Overflow

// DO NOT DO THIS. It is quadratic-time!
StringBuilder sb = new StringBuilder();
for(int i=0;i<100;i++){
    sb.insert(0, Integer.toString(i));
}

Warning: It defeats the purpose of StringBuilder, but it does what you asked.

Better technique (although still not ideal):

Reverse each string you want to insert.
Append each string to a StringBuilder.
Reverse the entire StringBuilder when you're done.

This will turn an O(n²) solution into O(n).

you can use strbuilder.insert(0,i);

stackoverflow.com › questions › 14453438 › append-to-string-at-certain-position

java - Append to String at certain position - Stack Overflow

Use the insert method.

info.insert(19, Misc.toTimestampLiteral(currentDate));

Use String#subString to cut 0 to 20 index and then add new String.

String str = miscFlag.substring(0,20)+ " "+Misc.toTimestampLiteral(currentDate)+" "+  miscFlag.substring(21);

docs.oracle.com › javase › 6 › docs › api › java › lang › StringBuilder.html

StringBuilder (Java Platform SE 6)

String.valueOf(java.lang.Object), append(java.lang.String) public StringBuilder append(String str) Appends the specified string to this character sequence. The characters of the String argument are appended, in order, increasing the length of this sequence by the length of the argument.

docs.oracle.com › cd › E17802_01 › j2se › j2se › 1.5.0 › jcp › beta2 › apidiffs › java › lang › StringBuilder.html

java.lang Class StringBuilder

String.valueOf(java.lang.Object) , append(java.lang.String) public StringBuilder append(String str) Appends the specified string to this character sequence. The characters of the String argument are appended, in order, increasing the length of this sequence by the length of the argument.

javahungry.blogspot.com › 2022 › 04 › stringbuilder-append-start.html

StringBuilder append to the start/front [3 ways] | Java Hungry

Using the insert() method 2. Using ... the start/front of the StringBuilder object using the insert() method. The insert() method of the StringBuilder class inserts the specified text at the specified index....

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Thedeveloperblog

thedeveloperblog.com › stringbuilder-java

Java StringBuilder Examples: append, insert

So we can quickly append, or insert, data. Here we use the insert method. It receives two arguments: an index, and a value we want to insert. Index: This is the first argument. To insert after the second character, use the value 2. And to insert at the start, use zero.

tutorialspoint.com › java › lang › stringbuilder_insert_chararray_len.htm

Java.lang.StringBuilder.insert() Method

The java.lang.StringBuilder.insert(int index, char[] str, int offset, int len) method inserts the string representation of a subarray of the str array argument into this sequence.

geeksforgeeks.org › java › stringbuilder-append-method-in-java-with-examples

StringBuilder append() Method in Java - GeeksforGeeks

July 11, 2025 - This version appends a subarray of characters to the StringBuilder, starting at the specified offset and with the specified length.

ulibgcj.sourceforge.net › javadoc › java › lang › StringBuilder.html

Set the character at the specified index. ... IndexOutOfBoundsException - if index is negative or >= length() (while unspecified, this is a StringIndexOutOfBoundsException) ... Append the String value of the argument to this StringBuilder.

codecademy.com › docs › java › stringbuilder › .insert()

Java | StringBuilder | .insert() | Codecademy

August 22, 2022 - If str is a String, a CharSequence*, or a char[] array**, the characters contained are inserted at index and its capacity is increased by the number of characters inserted. For other types, it behaves as if str was first converted to a string ...

Microsoft Learn

learn.microsoft.com › en-us › dotnet › api › java.lang.stringbuilder.append

StringBuilder.Append Method (Java.Lang) | Microsoft Learn

Then the character at index k in the new character sequence is equal to the character at index k in the old character sequence, if k is less than n; otherwise, it is equal to the character at index k-n in the argument sb.

scaler.com › home › topics › java › stringbuilder in java with examples, methods and constructors

StringBuilder in Java with Examples, Methods, and Constructors - Scaler Topics

May 3, 2023 - ... Modifying the text in the ... StringBuilder sequence. For inserting the text at the particular index, we will use StringBuilder.insert(index,text) method of the StringBuilder class....

docs.oracle.com › en › java › javase › 17 › docs › api › java.base › java › lang › StringBuilder.html

StringBuilder (Java SE 17 & JDK 17)

April 21, 2026 - Appends the string representation of the codePoint argument to this sequence. ... Returns the current capacity. ... Returns the char value in this sequence at the specified index.

developer.classpath.org › doc › java › lang › StringBuilder.html

StringBuilder (GNU Classpath 0.95 Documentation)

This is like #append(char), but will append two characters if a supplementary code point is given. ... Get the total number of characters this StringBuilder can support before it must be grown. Not to be confused with length. ... Get the character at the specified index.

jnior.com › jnior › janos-runtime-javadoc › java › lang › StringBuilder.html

StringBuilder (JanosRuntime JavaDOC)

public StringBuilder append(char[] str, int ofs, int len) Append character data from array starting at offset for the defined length. Parameters: str - character array containing data to append · ofs - starting index of the data · len - length of data to append ·

docs.oracle.com › en › java › javase › 18 › docs › api › java.base › java › lang › StringBuilder.html

StringBuilder (Java SE 18 & JDK 18)

August 18, 2022 - Appends the string representation of the codePoint argument to this sequence. ... Returns the current capacity. ... Returns the char value in this sequence at the specified index.

javastring.net › home › java stringbuilder class

Java StringBuilder Class

July 4, 2019 - append(): many overloaded methods to append primitive as well as objects to the StringBuilder. The data is always added at the end of the string builder. insert(): used to insert characters at the given index.