Let's summarize the Java 8 grammar from the perspective of an iOS engineer

Declaration of class in Java

Student.java

class Student {
    //Field declaration
    //Declare name of type String
    String name;
    //Declare int type score
    int score;
    //Declare a class constant of type int
    static final int MAX_SCORE = 100;
}

class Takashi {
    //The static modifier is the class name.Can be accessed by member name
    int mathScore = Student.MAX_SCORE;
}

Define a class

SampleClass.java

public class SampleClass { //name of the class
    private String name = "Sample"; //Field name(iOS:Property)
    public String action() { //Method name
        return name + "> " + "Action";
    }
}

About modifiers that can be specified for classes

Qualifiers that can be specified for fields and methods

Other commonly used modifiers

static modifier

The static modifier can define methods and fields that can be called without creating an instance. Fields and methods with the static modifier are called class members and can be called without creating an instance. How to use class members can be called by "class name.class member".

StaticTest.java

public class StaticTest {
    //Class field
    static String staticField = "World";

    //Class method
    static String staticMethod() {
        return "yes!";
    }

    //Instance field
    String instanceField = "Hello";

    //Instance method
    String instanceMethod() {
        return instanceField + " " + staticField + " " + staticMethod();
    }
}

How to use

StaticTestMain.java

public class StaticTestMain {
    public static void main(String... args) {
        System.out.print(StaticTest.staticField);

        System.out.print(StaticTest.staticMethod());

        StaticTest.staticField = "Japan";
        System.out.print(StaticTest.staticField);

        StaticTest test = new StaticTest();
        System.out.print(test.staticField);
        System.out.print(test.staticMethod());
        System.out.print(test.instanceMethod());
    }
}

final modifier

The final modifier is a modifier that makes a variable immutable.

Declaration method

FinalTest.java

public class FinalTest {
    //Class constant
    static final String GREETING_MESSAGE = "Hello";
}

How to use

StaticTestMain.java

public class StaticTestMain {
    public static void main(String... args) {
        System.out.print(FinalTest.GREETING_MESSAGE);
    }
}

I learned a lot. I would like to study the design patterns in Android development as soon as possible.

References

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