How to concatenate strings in Java

How to connect strings in Java: 1. Use operators to connect strings, code such as ""I'm a" "student""; 2. Connect strings through the concat method of String, code such as "public String concat (String str)".

The operating environment of this article: Windows 7 system, Dell G3 computer, Java version 8.0.

Concatenation in Java is the operation of joining two strings together. You can concatenate strings using the addition ( ) operator or the concat () method of String.

Using the operator

Using the operator is the most common way to concatenate two strings in Java. You can provide a variable, number, or string literal (always enclosed in double quotes).

For example, to combine the strings "I'm a" and "student", write:

"I’m a" + " student"

Be sure to remember to add spaces so that when you print the combined strings, they are separated correctly its words. For example, notice above that "student" starts with a space.

Combining multiple strings

You can string any number of operands together, for example:

"I’m a" + " student" + "! And so are you."

In a print statement Using Operators

Normally, the operator is used in print statements. You could write something like:

System.out.println("pan" + "handle");

This will print:

panhandle

Mixture of combined objects

The operator " " is usually used in arithmetic operator unless one of its operands is a String. If so, it converts the other operand to a String before concatenating the second operand to the end of the first operand.

For example, in the example below, age is an integer, so the operator will first convert it to a String and then combine the two strings together. (The operator does this behind the scenes by calling its toString() method; you won't see this happen.)

int age = 12;
System.out.println("My age is " + age);

This will print:

My age is 12

Using Concat Method

String class has a method concat() which performs the same operation. This method acts on the first string and then combines the strings into arguments:

public String concat (String str)

For example:

String myString = " I have decided to stick with love.;
myString = myString.concat(" Hate is too great a burden to bear.");
System.out.println(myString);

This will print:

I have decided to stick with love. Hate is too great a burden to bear.

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