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Java – StringBuffer substring() method

May 20, 2017 SJ String Handling 0

In this article, we will discuss StringBuffer’s substring() method which is used to get substring (partial string or portion of string from StringBuffer as per specified range)

1. StringBuffer’s substring() method:

  • This StringBuffer method is used to get sub-string for the specified begin-indexand end-index
  • There are 2 variants or overloaded substring() method,
    1. 1st variant returns substring starting from specified index-position till length
    2. 2nd variant returns substring starting from specified index-position to specified end index-position
  • In addition to this, there is one more StringBuffer method similar to 2nd variant i.e.; subSequence() method

1.1 Method Signature:

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public String substring(int start);
 
public String substring(int start, int end);
 
public CharSequence subSequence(int start, int end);

1.2 Parameters:

  • Start –> start index (indicates from where string need to be extracted and it is inclusive)
  • end –> end index (indicates till where string need to be extracted and it is exclusive)

1.3 Returns:

substring() method

Returns

public String substring(int start);Returns substring from the invoking StringBuffer object, starting from specified begin-index
public String substring(int start, int end);Returns substring from the invoking StringBuffer object, starting from specified begin-index till end-index
public CharSequence subSequence(int start, int end);Very similar to substring(beginIndex, endIndex);

 

Returns char sequence from the invoking StringBuffer object, starting from specified begin-index till end-index

1.4 Throws:

  • substring() method throws StringIndexOutOfBoundsException, if index value passed falls out of range i.e.;
    1. if either start-index or end-index is negative (<0)
    2. if start-index is greater than end-index
    3. if end-index is greater than length()
  • subsequence() method throws IndexOutOfBoundsException, if index value passed falls out of range i.e.;
    1. if either start-index or end-index is negative (<0)
    2. if start-index is greater than end-index
    3. if end-index is greater than length()

2. Examples on substring() method:

2.1 To get sub-string starting from specified begin-index

Method Signature:

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public String substring(int start);

StringBufferSubstringMethod.java

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package in.bench.resources.stringbuffer.methods;
 
public class StringBufferSubstringMethod {
 
    public static void main(String[] args) {
 
        // StringBuffer 1: to get substring() -
        // starting from 10th index-position
        StringBuffer sb1 = new StringBuffer(
                "Java is a super cool language");
        String subString1 = sb1.substring(10);
        System.out.println("sb1.substring(10) is : "
                + subString1);
 
        // StringBuffer 2: to get substring() -
        // starting from 24th index-position
        StringBuffer sb2 = new StringBuffer(
                "BenchResources.Net ");
        sb2.append("is a Java weblog"); // 1st append
        String subString2 = sb2.substring(24);
        System.out.println("\nsb2.substring(24) is : "
                + subString2);
 
        // StringBuffer 3: to get substring() -
        // starting from 13th index-position
        StringBuffer sb3 = new StringBuffer(
                "String class ");
        sb3.append("has useful "); // 1st append
        sb3.append("methods"); // 2nd append
        String subString3 = sb3.substring(13);
        System.out.println("\nsb3.substring(13) is : "
                + subString3);
    }
}

Output:

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sb1.substring(10) is : super cool language
 
sb2.substring(24) is : Java weblog
 
sb3.substring(13) is : has useful methods

2.2 To get substring starting from specified begin-index till specified end-index

Method Signature:

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public String substring(int start, int end);

StringBufferSubstringMethod2.java

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package in.bench.resources.stringbuffer.methods;
 
public class StringBufferSubstringMethod2 {
 
    public static void main(String[] args) {
 
        // StringBuffer 1: to get substring() -
        // starting from 10th till 20th index-position
        StringBuffer sb1 = new StringBuffer(
                "Java is a super cool language");
        String subString1 = sb1.substring(10, 20);
        System.out.println("sb1.substring(10, 20) is : "
                + subString1);
 
        // StringBuffer 2: to get substring() -
        // starting from 24th till 28th index-position
        StringBuffer sb2 = new StringBuffer(
                "BenchResources.Net ");
        sb2.append("is a Java weblog"); // 1st append
        String subString2 = sb2.substring(24, 28);
        System.out.println("\nsb2.substring(24, 28) is : "
                + subString2);
 
        // StringBuffer 3: to get substring() -
        // starting from 7th till 23rd index-position
        StringBuffer sb3 = new StringBuffer(
                "String class ");
        sb3.append("has useful "); // 1st append
        sb3.append("methods"); // 2nd append
        String subString3 = sb3.substring(07, 23);
        System.out.println("\nsb3.substring(07, 23) is : "
                + subString3);
    }
}

Output:

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sb1.substring(10, 20) is : super cool
 
sb2.substring(24, 28) is : Java
 
sb3.substring(07, 23) is : class has useful

2.3 To get char sequence starting from specified begin-index till specified end-index

  • Note: very similar to substring(beginIndex, endIndex);

Method Signature:

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public CharSequence subSequence(int start, int end);

StringBufferSubsequenceMethod.java

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package in.bench.resources.stringbuffer.methods;
 
public class StringBufferSubsequenceMethod {
 
    public static void main(String[] args) {
 
        // Example 1: to get subSequence() -
        // starting from 10th till 20th index-position
        StringBuffer sb1 = new StringBuffer(
                "Java is a super cool language");
        CharSequence charSequence1 = sb1.substring(10, 20);
        System.out.println("sb1.subSequence(10, 20) is : "
                + charSequence1);
 
        // Example 2: to get subSequence() -
        // starting from 24th till 28th index-position
        StringBuffer sb2 = new StringBuffer(
                "BenchResources.Net ");
        sb2.append("is a Java weblog"); // 1st append
        CharSequence charSequence2 = sb2.subSequence(24, 28);
        System.out.println("\nsb2.subSequence(24, 28) is : "
                + charSequence2);
 
        // Example 3: to get subSequence() -
        // starting from 7th till 23rd index-position
        StringBuffer sb3 = new StringBuffer(
                "String class ");
        sb3.append("has useful "); // 1st append
        sb3.append("methods"); // 2nd append
        CharSequence charSequence3 = sb3.subSequence(07, 23);
        System.out.println("\nsb3.subSequence(07, 23) is : "
                + charSequence3);
    }
}

Output:

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sb1.subSequence(10, 20) is : super cool
 
sb2.subSequence(24, 28) is : Java
 
sb3.subSequence(07, 23) is : class has useful

Related Articles:

References:

Happy Coding !!
Happy Learning !!

Java - StringBuilder class
Java - StringBuffer reverse() method

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