Writing methods

Throwing exceptions

Throwing exceptions using the standard method addLine() works roughly like this:

  public JavaMethod getDifficultMethod(JavaSource pSource) {
    JavaMethod jm = pSource.newJavaMethod("difficultMethod", "void", "public");
    jm.addLine("throw new (", NotImplementedException.class, "(",
               JavaSource.getQuoted("The method 'difficultMethod' is not yet implemented."),
               ");");
    return jm;
  }

Using the method addThrowNew(), this could be rewritten as follows:

  public JavaMethod getDifficultMethod(JavaSource pSource) {
    JavaMethod jm = pSource.newJavaMethod("difficultMethod", "void", "public");
    jm.addThrowNew(NotImplementedException.class,
                  JavaSource.getQuoted("The method 'difficultMethod' is not yet implemented."));
    return jm;
  }

If .. else if .. else blocks

Suggest the following example:

  public JavaMethod getValueOfMethod(JavaSource pSource) {
    JavaMethod jm = pSource.newJavaMethod("valueOf", "int", "public");
    jm.addParam(String.class, "s");
    jm.addLine("if (", JavaSource.getQuoted("FOO"), ".equals(s)) {");
    jm.indent();
    jm.addLine("return foo;");
    jm.unindent();
    jm.addLine("} else if (", JavaSource.getQuoted("BAR"), ".equals(s)) {");
    jm.indent();
    jm.addLine("return bar;");
    jm.unindent();
    jm.addLine("} else {");
    jm.indent();
    jm.addThrowNew(IllegalArgumentException.class,
                   JavaSource.getQuoted("Invalid value for s: "), " + s");
    jm.unindent();
    jm.addLine("}");
    return jm;
  }

This example could also be written like this:

  public JavaMethod getValueOfMethod(JavaSource pSource) {
    JavaMethod jm = pSource.newJavaMethod("valueOf", "int", "public");
    jm.addParam(String.class, "s");
    jm.addIf(JavaSource.getQuoted("FOO"), ".equals(s)");
    jm.addLine("return foo;");
    jm.addElseIf(JavaSource.getQuoted("BAR"), ".equals(s)");
    jm.addLine("return bar;");
    jm.addElse();
    jm.addThrowNew(IllegalArgumentException.class,
                   JavaSource.getQuoted("Invalid value for s: "), " + s");
    jm.addEndIf();
    return jm;
  }

The rewritten example is both shorter and more readable.

try .. catch blocks

A try .. catch block is typically written like this:

  public JavaMethod getAsIntMethod(JavaSource pSource) {
    JavaMethod jm = pSource.newJavaMethod("asInt", "int", "public");
    jm.addParam(String.class, "s");
    jm.addLine("try {");
    jm.indent();
    jm.addLine("return Integer.toString(s);");
    jm.unindent();
    jm.addLine("} catch (", NumberFormatException.class, " e) {");
    jm.indent();
    jm.addLine("e.printStackTrace();");
    jm.addLine("return 1;");
    jm.unindent();
    jm.addLine("}");
    return jm;
  }

To simplify the example, use the addTry() and addCatch() methods:

  public JavaMethod getAsIntMethod(JavaSource pSource) {
    JavaMethod jm = pSource.newJavaMethod("asInt", "int", "public");
    jm.addParam(String.class, "s");
    jm.addTry();
    jm.addLine("return Integer.toString(s);");
    jm.addCatch(NumberFormatException.class, "e");
    jm.addLine("e.printStackTrace();");
    jm.addLine("return 1;");
    jm.addEndTry();
    return jm;
  }

An even shorter version would be to replace

    jm.addCatch(NumberFormatException.class, "e");

with

    jm.addCatch(NumberFormatException.class);

The method version with a single parameter uses the default variable name e.