什么是Java的“延迟”等价物

Question

This is just a short example of Go code:

package main

import "fmt"

func main() {
    defer fmt.Println("world") //use of keyword 'defer'

    fmt.Println("hello")
}

I am finding an equivalent of 'defer' in Java.

Instead of 'defer' I can use

try {
    //do something
} finally {
    //code using defer
}

Is there any alternative without using try/catch/finally?

Answer 1

Java 7 has a try-with-resources statement.

The try-with-resources statement is a try statement that declares one or more resources. A resource is an object that must be closed after the program is finished with it. The try-with-resources statement ensures that each resource is closed at the end of the statement. Any object that implements java.lang.AutoCloseable, which includes all objects which implement java.io.Closeable, can be used as a resource.

The following example reads the first line from a file. It uses an instance of BufferedReader to read data from the file. BufferedReader is a resource that must be closed after the program is finished with it:

static String readFirstLineFromFile(String path) throws IOException {
    try (BufferedReader br = new BufferedReader(new FileReader(path))) {
        return br.readLine();
    }
}

In this example, the resource declared in the try-with-resources statement is a BufferedReader. The declaration statement appears within parentheses immediately after the try keyword. The class BufferedReader, in Java SE 7 and later, implements the interface java.lang.AutoCloseable. Because the BufferedReader instance is declared in a try-with-resource statement, it will be closed regardless of whether the try statement completes normally or abruptly (as a result of the method BufferedReader.readLine throwing an IOException).