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Summary of return usage

angryTom

Jul 23, 2019 pm 01:36 PM

javareturn

Usage of return in java: 1. Return null in a method with an object reference return type, with syntax such as "public Button doStuff(){}"; 2. Return anything in a method with a basic return type Value or variable, syntax such as "public int foo(){}" and so on.

Summary of return usage

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##return usage summary:

1. In a method with a return value, return the value of the type specified by the method and end the method execution at the same time; 2. Also Can be used in methods whose return value is void to terminate the method execution;

break and return

## Break is used to jump out of loops, such as for, while, and do-while, but not the function Return causes the entire function to return, regardless of what follows. Whether it is inside the loop or outside the loop, it will not be executed.

1. You can return null in a method with an object reference return type

public Button doStuff（）{
    return null；
}

2. Array is a completely legal return type

public String[] go(){
    return new String[]{"wangsan","wangsan","wangsi"};
}

3. Within a method with a basic return type, you can return any Values or variables, as long as they can be implicitly converted to the declared return type

public int foo(){
    char c=‘c’;
    return c;//char可以转化成int
}

4. Within a method with a basic return type, any value or variable can be returned, as long as they can Display forced conversion to the declared return type (this is not an example)

5. You must not return any value from a method with a return type of void (^_^), of course you can Use return to interrupt the program.

public void bar(int a){
    //负数则中断操作，
    if(a<0){
    return;
    }
    //do other things
}

6. Within a method with an object reference return type, any value or variable can be returned as long as they can be implicitly converted to the declared return type (passing the is-a test That’s it)

public Animal getAnimal(){
    return new Dog();//只要Dog继承Animal即可
}

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