String.valueOf() Method
This static method takes an argument as int and returns a string form of the integer value. Here, static means that the string class name should be used without instantiating the string object. The full syntax for this method is:
The following program illustrates the use of this method for different integer values:
public static void main(String[] args) {
int i1 = 5, i2 = -5, i3 = 256, i4 = -256;
String str1 = String.valueOf(i1); String str2 = String.valueOf(i2);
String str3 = String.valueOf(i3); String str4 = String.valueOf(i4);
System.out.print(str1); System.out.print(", ");
System.out.print(str2); System.out.print(", ");
System.out.print(str3); System.out.print(", ");
System.out.print(str4); System.out.println();
}
}
The output is:
The program begins with no import statement. All the code is in the main() method. The first line in the main method declares the integers with assignments. The second code segment does the conversions. The third code segment prints out the results.
Integer.toString()
There is a class with the name, Integer. It does not need to be imported by the program to be used. It is a wrapper to the primitive int type. It has a method, which is toString(). This method returns the string form of the integer value. The full syntax for this is:
It is a static method. Any static method does not require the instantiation of the class (String) in order to be used. The following program illustrates the use of this method for different integer values:
public static void main(String[] args) {
int i1 = 5, i2 = -5, i3 = 256, i4 = -256;
String str1 = Integer.toString(i1); String str2 = Integer.toString(i2);
String str3 = Integer.toString(i3); String str4 = Integer.toString(i4);
System.out.print(str1); System.out.print(", ");
System.out.print(str2); System.out.print(", ");
System.out.print(str3); System.out.print(", ");
System.out.print(str4); System.out.println();
}
}
The output is:
The program begins with no import statement. All the code is in the main() method. The first line in the main method declares the integers with assignments. The second code segment does the conversions. The third code segment prints out the results.
StringBuffer or StringBuilder
The StringBuffer or StringBuilder class is like a string class. However, its characters can be changed, while the characters of the string class cannot be changed. Both of these classes have the append() method that can be used to add value to the object. The append method can take an int as an argument. The integer value is converted into a character and added to the string.
StringBuffer
The following program illustrates the case for a StringBuffer object:
public static void main(String[] args) {
int i1 = 5, i2 = -5, i3 = 256, i4 = -256;
StringBuffer str1 = new StringBuffer(); StringBuffer str2 = new StringBuffer();
StringBuffer str3 = new StringBuffer(); StringBuffer str4 = new StringBuffer();
str1.append(i1); str2.append(i2); str3.append(i3); str4.append(i4);
System.out.print(str1); System.out.print(", ");
System.out.print(str2); System.out.print(", ");
System.out.print(str3); System.out.print(", ");
System.out.print(str4); System.out.println();
}
}
The output is:
The program begins with no import statement. All the code is in the main() method. The first line in the main method declares the integers with assignments. The second code segment does the conversions. The third code segment prints out the results.
StringBuilder
The following program illustrates the case for the StringBuilder object:
public static void main(String[] args) {
int i1 = 5, i2 = -5, i3 = 256, i4 = -256;
StringBuilder str1 = new StringBuilder(); StringBuilder str2 = new StringBuilder();
StringBuilder str3 = new StringBuilder(); StringBuilder str4 = new StringBuilder();
str1.append(i1); str2.append(i2); str3.append(i3); str4.append(i4);
System.out.print(str1); System.out.print(", ");
System.out.print(str2); System.out.print(", ");
System.out.print(str3); System.out.print(", ");
System.out.print(str4); System.out.println();
}
}
The output is:
The program begins with no import statement. All the code is in the main() method. The first line in the main method declares the integers with assignments. The second code segment does the conversions. The third code segment prints out the results.
String.format()
The string class has the format() method. The full syntax is:
It is a static method. It consists of text interspersed with format specifiers. The first argument is called the format string, though it is still to be formatted. The second argument is an argument list. If the format string has only one specifier, the argument list should have only one argument, the integer value, not quotes. The specifier for integer is %d .
public static void main(String[] args) {
int i1 = 5, i2 = -5, i3 = 256, i4 = -256;
String str1 = String.format("%d", i1); String str2 = String.format("%d", i2);
String str3 = String.format("%d", i3); String str4 = String.format("%d", i4);
System.out.print(str1); System.out.print(", ");
System.out.print(str2); System.out.print(", ");
System.out.print(str3); System.out.print(", ");
System.out.print(str4); System.out.println();
}
}
The output is:
The program begins with no import statement. All the code is in the main() method. The first line in the main method declares the integers with assignments. The second code segment does the conversions. The third code segment prints out the results.
String Concatenation Operator
The string concatenation operator is + . If an empty string is concatenated with an integer, that integer becomes the string. The following program illustrates this:
public static void main(String[] args) {
int i1 = 5, i2 = -5, i3 = 256, i4 = -256;
String str1 = "" + i1; String str2 = "" + i2;
String str3 = "" + i3; String str4 = "" + i4;
System.out.print(str1); System.out.print(", ");
System.out.print(str2); System.out.print(", ");
System.out.print(str3); System.out.print(", ");
System.out.print(str4); System.out.println();
}
}
The output is:
The program begins with no import statement. All the code is in the main() method. The first line in the main method declares the integers with assignments. The second code segment does the conversions. The third code segment prints out the results.
Conclusion
The following methods and operator, can be used to convert an integer into a string: String.valueOf(), Integer.toString(), StringBuffer.append(), StringBuilder.append(), String.format() and the string concatenation operator.