SimplifyMe.java

public String foo(boolean p1, boolean p2, long p3) {
    String result = "a";
    if (p1) result += "b";
    if (p2) result += "c";
    if (p1 && p2 && p3 < 5L) result += "d";
    if (p3 == 1L) result = "e" + result;
    result = "f" + result;
    return result;
}
private String bar1() {
    return foo(true, false, 6L);
}
private String bar2() {
    return foo(true, true, 6L);
}


// Step 0.
// ============

// make a spreadsheet with all callers and their parameters

// +--------+------+-------+----+
// | caller |  p1  |  p2   | p3 |
// +--------+------+-------+----+
// | bar1   | true | false | 6L |
// | bar2   | true | true  | 6L |
// |        | true | ?     | 6L |
// +--------+------+-------+----+

// Step 1.
// ============

// refactor foo and run application with -enableassertions

public String foo(boolean p1, boolean p2, long p3) {
    assert p1 == true;
    assert p3 == 6L;
    return p2 ? "fabc" : "fab";
}


// Step 2.
// ============

// remove unneeded parameters and alter all callers

public String refactoredFoo(boolean p2) {
    return p2 ? "fabc" : "fab";
}
private String bar1(){
    return foo(false);
}
private String bar2(){
    return foo(true);
}


// Step 3.
// ============

// get rid of boolean parameters and use enums instead

public enum ImportantChoice {
    OMIT_C, INCLUDE_C;
}
public String refactoredFoo(ImportantChoice p2) {
    return p2 == INCLUDE_C ? "fabc" : "fab";
}
private String bar1() {
    return foo(OMIT_C);
}
private String bar2() {
    return foo(INCLUDE_C);
}