Java StringWriter Tutorial
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StringWriter is a subclass of Writer that manages a StringBuffer object. The characters written to the StringWriter will be appended to the StringBuffer object it manages.
The StringWriter class does not use I/O or Network operations so you can use it without closing it.
- TODO Link!
- TODO Link!
StringWriter constructor
StringWriter() StringWriter​(int initialSize)
Besides those methods inherited from its parent class, StringWriter also has a few more notable methods of its own, including:
| String toString() | Returns the String of the buffer. |
| StringBuffer getBuffer() | Returns the StringBuffer object that StringWriter is currently managing. |
| StringWriter append( char c) | Append a character to the buffer, the same as calling StringWriter.write(char) method, but this method returns the current StringWriter object, this allows calling another method of StringWriter instead of terminating with a semicolon (;) |
| StringWriter append( CharSequence csq) | Similar to the StringWriter.write(CharSequence) method, but returns the current StringWriter object. |
| StringWriter append( CharSequence csq, int start, int end) | Similar to the StringWriter.write(CharSequence,int,int) method, but returns the current StringWriter object. |
StringWriterEx1.java
package org.o7planning.stringwriter.ex;
import java.io.StringWriter;
public class StringWriterEx1 {
public static void main(String[] args) {
StringWriter sw = new StringWriter();
sw.write("Java Tutorial");
sw.append("\n").append("C# Tutorial").append("\n").append("Python Tutorial");
String s = sw.toString();
System.out.println(s);
}
}
Output:
Java Tutorial C# Tutorial Python Tutorial
Usually when an exception occurs, you often see "Stack Trace" information printed on the Console screen, how to get this content as a String?
StringWriterEx3.java
package org.o7planning.stringwriter.ex;
import java.io.PrintWriter;
import java.io.StringWriter;
public class StringWriterEx3 {
public static void main(String[] args) {
try {
int a = 100/0; // Exception occur here
} catch(Exception e) {
String s = getStackTrace(e);
System.err.println(s);
}
}
public static String getStackTrace(Throwable t) {
StringWriter writer = new StringWriter();
// Create PrintWriter via PrintWriter(Writer) constructor.
PrintWriter pw = new PrintWriter(writer);
// Call method: Throwable.printStackTrace(PrintWriter)
t.printStackTrace(pw);
pw.close();
String s = writer.getBuffer().toString();
return s;
}
}
Output:
java.lang.ArithmeticException: / by zero
at org.o7planning.stringwriter.ex.StringWriterEx5.main(StringWriterEx5.java:10)
GetStackTraceEx.java
package org.o7planning.printwriter.ex;
import java.io.PrintWriter;
import java.io.StringWriter;
public class GetStackTraceEx {
public static void main(String[] args) {
try {
int a = 100/0; // Exception occur here
} catch(Exception e) {
String s = getStackTrace(e);
System.err.println(s);
}
}
public static String getStackTrace(Throwable t) {
StringWriter stringWriter = new StringWriter();
// Create PrintWriter via PrintWriter(Writer) constructor.
PrintWriter pw = new PrintWriter(stringWriter);
// Call method: Throwable.printStackTrace(PrintWriter)
t.printStackTrace(pw);
pw.close();
String s = stringWriter.getBuffer().toString();
return s;
}
}
Output:
java.lang.ArithmeticException: / by zero
at org.o7planning.printwriter.ex.GetStackTraceEx.main(GetStackTraceEx.java:10)
