How to compare two strings in Java?
Aug 04, 2025 am 11:03 AM
Use the .equals() method to compare string content, because == only compare object references rather than content; 1. Use .equals() to compare string values equally; 2. Use .equalsIgnoreCase() to compare case ignoring; 3. Use .compareTo() to compare strings in dictionary order, returning 0, negative or positive numbers; 4. Use .compareToIgnoreCase() to compare case ignoring; 5. Use Objects.equals() or safe call method to process null strings to avoid null pointer exceptions. In short, you should avoid using == for string content comparisons unless it is explicitly necessary to check whether the objects are the same.
Comparing two strings in Java might seem straightforward, but there are important differences between using == and the .equals() method — and using the wrong one can lead to bugs.
Use .equals() to compare string content
The most important rule: don't use == to compare the values of two strings . The == operator checks whether two references point to the same object in memory, not whether the string contents are the same.
Instead, use the .equals() method to compare the actual characters in the strings:
String str1 = "hello";
String str2 = "hello";
if (str1.equals(str2)) {
System.out.println("Strings are equal");
} This returns true because both strings contain the same sequence of characters.
?? Example of what not to do:
if (str1 == str2) { ... } // Don't rely on this for value comparisonThis may work sometimes due to string interning, but it's unreliable, especially with strings from user input or
new String("...").
Handle case sensitivity with .equalsIgnoreCase()
If you want to ignore case when comparing strings (eg, "Hello" vs "HELLO"), use .equalsIgnoreCase() :
String str1 = "Hello";
String str2 = "HELLO";
if (str1.equalsIgnoreCase(str2)) {
System.out.println("Strings are equal (ignoring case)");
}This is useful for things like user login or search functionality where case shouldn't matter.
Compare strings alphabetically using .compareTo()
If you need to know the lexicographical order (dictionary order) of two strings, use .compareTo() :
String str1 = "apple";
String str2 = "banana";
int result = str1.compareTo(str2);
if (result < 0) {
System.out.println("str1 comes before str2");
} else if (result > 0) {
System.out.println("str1 comes after str2");
} else {
System.out.println("str1 and str2 are equal");
}- Returns 0 if strings are equal
- Returns a negative number if
str1comes beforestr2 - Returns a positive number if
str1comes afterstr2
Use .compareToIgnoreCase() if you want case-insensitive ordering.
Watch out for null strings
Calling .equals() on a null string will throw a NullPointerException . To avoid this, especially when the first string might be null , consider:
- Using
Objects.equals()(recommended):
import java.util.Objects;
String str1 = null;
String str2 = "hello";
if (Objects.equals(str1, str2)) {
System.out.println("Equal");
} else {
System.out.println("Not equal"); // This will print
} Objects.equals() safely handles null values — it returns true only if both are null , or both are non-null and .equals() returns true .
Alternatively, avoid calling .equals() on the potentially null string:
if ("hello".equals(str1)) { ... } // Safe even if str1 is null This way, you're calling .equals() on a literal (which is never null ).
So to recap:
- ? Use
.equals()for content comparison - ? Use
.equalsIgnoreCase()for case-insensitive checks - ? Use
.compareTo()for sorting/ordering - ? Handle
nulls withObjects.equals()or safe calling order
Basically, just don't use == unless you explicitly want to check object identity — and that's rare in everyday string comparison.
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