catch / Reference / Processing.org

Name

catch

Description

The catch keyword is used with try to handle exceptions. Sun's Java documentation defines an exception as "an event, which occurs during the execution of a program, that disrupts the normal flow of the program's instructions." This could be, for example, an error while a file is read.

Examples

BufferedReader reader;
String line;
 
void setup() {
  // Open the file from the createWriter() example
  reader = createReader("positions.txt");    
}
 
void draw() {
  try {
    line = reader.readLine();
  } catch (IOException e) {
    e.printStackTrace();
    line = null;
  }
  if (line == null) {
    // Stop reading because of an error or file is empty
    noLoop();  
  } else {
    String[] pieces = split(line, TAB);
    int x = int(pieces[0]);
    int y = int(pieces[1]);
    point(x, y);
  }
}

Syntax

try {
tryStatements
} catch (exception) {
catchStatements
}

Parameters

tryStatementsif this code throws an exception, then the code in "catch" is run
exceptionthe Java exception that was thrown
catchStatementscode that handles the exception

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