Inline

Introduction

IntelliJ IDEA provides the following inline refactorings:

• Inline Variable refactoring replaces redundant variable usage with its initializer. See example. This refactoring is opposite to the Extract Variable refactoring.

  The variable must be initialized at declaration. If the initial value is modified somewhere in the code, only the occurrences before modification will be inlined.

• Inline Method refactoring results in placing method's body into the body of its caller(s). You can opt to:
  • inline all occurrences of the method, and delete the method
  • inline only a single occurrence, and retain the method

  See example.

  This refactoring is opposite to Extract Method.

• Inline to Anonymous Class refactoring allows replacing redundant class with its contents. Starting with Java 8, the inlined anonymous classes can be converted to lambdas automatically. See example.
• Inline Constructor allows compressing a chain of constructors, if one of them is a special case of another. See example.
• Inline JSP/JSPX works like a regular Java inline refactoring.
• Inline Superclass refactoring results in pushing superclass' methods into the class where they are used, and removing the superclass.

Examples

Inline variable

public void method() {
    int number = anotherClass.intValue();
    int b = a + number;
}

public void method() {
    int b = a + anotherClass.intValue();
}

public void method() {
    AnotherClass.InnerClass aClass = anotherClass.innerClass;
    int a = aClass.i;
}

public void method() {
    int a = anotherClass.innerClass.i;
}

Inline method

public void method() {
    int c=add(a,b);
    int d=add(a,c);
}

private int add(int a, int b) {
    return a+b;
}

public void method() {
    int c= a + b;
    int d= a + c;
}

public ArrayList method() {
    String[] strings = {"a","b","c"};
    ArrayList list=add(strings);
    return list;
}

private ArrayList add(String[] strings) {
    ArrayList list = new ArrayList();
    for (int i=0; i< strings.length; i++)
        {list.add(strings[i]);}
    return list;
}

public ArrayList method() {
    String[] strings = {"a","ab","abc"};
    ArrayList list1 = new ArrayList();
    for (int i=0; i< strings.length; i++)
        {list.add(strings[i]);}
    ArrayList list = list1;
    return list;
}

Inline constructor

public class Class {
    public int varInt;
    public Class() {
        this(0);
    }

    public Class(int i) {
        varInt=i;
    }

    public void method() {
        Class aClass=new Class();
        ...
    }
}

public class Class {
    public int varInt;
    public Class(int i) {
        varInt=i;
    }
    public void method() {
        Class aClass=new Class(0);
        ...
    }
}

Inline superclass

public class Bar {
    ...
    int calculations1() { ... }
    int calculations2() { ... }
}

class Foo extends Bar {
    int someMethod() {
        ...
        if (something > calculations1()) {
            ...
            return calculations2();
        }
        ...
    }
}

class Foo {
    ...
    int someMethod() {
        ...
        if (something > calculations1()) {
            ...
            return calculations2();
        }
        ...
    }
    int calculations1() {...}
    int calculations2() {...}
}

Inline to anonymous class

import java.util.*;
public class Main {
    public class MyComparator implements Comparator<String> {
        @Override
        public int compare(String s1, String s2) {
            return 0;
        }
    }

    void sort(List<String> scores) {
        scores.sort(new MyComparator());
    }
}

import java.util.*;

public class Main {

    void sort(List<String> scores) {
        scores.sort((s1, s2) -> 0);
    }
}

Performing inline refactoring

1. Place the caret in the editor at the desired symbol to be inlined.
2. Do one of the following:
   • On the main menu or on the context menu, choose Refactor | Inline.
   • Press Ctrl+Alt+N.
3. In the Inline dialog , that corresponds to the selected symbol, specify the inlining options.
4. Preview and apply changes.