# Java reflect Field get class variables

**URL:** <https://discourse.processing.org/t/java-reflect-field-get-class-variables/14357>\
**Category:** Coding Questions\
**Created:** [October 1, 2019, 7:07pm UTC](https://discourse.processing.org/t/java-reflect-field-get-class-variables/14357 "2019-10-01T19:07:12Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![GeorgeJava](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/georgejava/32/7646_2.png) [@GeorgeJava](https://discourse.processing.org/u/GeorgeJava)\
**Post date:** [October 1, 2019, 7:07pm UTC](https://discourse.processing.org/t/java-reflect-field-get-class-variables/14357/1 "2019-10-01T19:07:12Z")

</div>

Hello, i want to load all variables from sketch and want to check some variables in the specific class and do some changes, how i can get class from Field ? 😐🤔

```auto
import java.lang.reflect.Field;

testClass test = new testClass(125); // save some number, wich we want to edit or read/write

void setup() {
  println(test); // only chech if return "toString" is good
  
  final Class <?extends PApplet> c = getClass(); // read all variables

  final Field[] fields = c.getDeclaredFields(); // get it to the array

  int x = fields[0].i; // <-- I dont know hot to load the class "test" and get var "i", can you help me ?

  // HOW TO GET FIELD CLASS NAME LIKE A "testClass" ?
  // ... AND after that load list of variables in the class and get someone or rewrite to this variable some other number..

  exit();
}

class testClass { // class for test
  int i = 0;
  testClass(int i) {
    this.i = i;
  }
  String toString() {
    return "This is class, iam returning some string...";
  }
}

```

Thanks, George.

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<div class="post-metadata">

**Author:** ![GoToLoop](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/gotoloop/32/86_2.png) [@GoToLoop](https://discourse.processing.org/u/GoToLoop)\
**Post date:** [October 1, 2019, 7:28pm UTC](https://discourse.processing.org/t/java-reflect-field-get-class-variables/14357/2 "2019-10-01T19:28:53Z")

</div>

[Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/lang/reflect/Field.html#get(java.lang.Object)](http://Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/lang/reflect/Field.html#get(java.lang.Object))

```auto
import java.lang.reflect.Field;

final TestClass test = new TestClass((int) random(1000));

void setup() {
  final Class<TestClass> c = TestClass.class;
  final Field[] fields = c.getDeclaredFields();

  printArray(fields);
  println();

  try {
    for (final Field f : fields) println(f.get(test));
  } 
  catch (final ReflectiveOperationException e) {
    throw new RuntimeException(e);
  }

  exit();
}

class TestClass {
  int i;

  TestClass(int ii) {
    i = ii;
  }

  String toString() {
    return str(i);
  }
}

```

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<div class="post-metadata">

**Author:** ![GeorgeJava](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/georgejava/32/7646_2.png) [@GeorgeJava](https://discourse.processing.org/u/GeorgeJava)\
**Post date:** [October 2, 2019, 7:49am UTC](https://discourse.processing.org/t/java-reflect-field-get-class-variables/14357/3 "2019-10-02T07:49:01Z")

</div>

THANKS, but can i get this class withou inserting “test” object for Getting class ?

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<div class="post-metadata">

**Author:** ![GoToLoop](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/gotoloop/32/86_2.png) [@GoToLoop](https://discourse.processing.org/u/GoToLoop)\
**Post date:** [October 2, 2019, 7:56am UTC](https://discourse.processing.org/t/java-reflect-field-get-class-variables/14357/4 "2019-10-02T07:56:38Z")

</div>

- A `class` itself is merely a description for fields, methods & constructors.
- Non-`static` fields only got values stored in them after a class is instantiated.
- Therefore, we’ve gotta have an instance of a `class` prior to use the reflective method Field::**get()**.