https://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html


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.



public interface AutoCloseable {
    void close() throws Exception;
}

public interface Closeable extends AutoCloseable {
    public void close() throws IOException;
}

使用 try-with-resources 

try (BufferedReader br =
                   new BufferedReader(new FileReader(path))) {
        return br.readLine();
}

使用 try finally

    BufferedReader br = new BufferedReader(new FileReader(path));
    try {
        return br.readLine();
    } finally {
        if (br != null) br.close();
    }


多个资源

try(FileInputStream input = new FileInputStream("file.txt"); BufferedInputStream bufferedInput = new BufferedInputStream(input))
    {

        int data = buffereInput.read();
        while(data != -1){
            System.out.println( (char) data);
            data = bufferedInput.read();
        }
    }
    
创建顺序的逆序关闭
关闭顺序 BufferedInputStream  FileInputStream
    


完整例子


public class TryResourceTest implements AutoCloseable{
	
	private String name;
	private boolean error = false;
	
	public TryResourceTest(String name,boolean error){
		this.name = name;
		this.error = error;
	}

	public static void main(String[] args) throws Exception {
			
		try(TryResourceTest test1 = new TryResourceTest("test1",false)){
			test1.hello();
		}	
		System.out.println("111");
		
		// 抛出异常 也会自动关闭
		try(TryResourceTest test2 = new TryResourceTest("test2",true)){
			test2.hello();
		}
		
		// 这里不会运行
		System.out.println("222");

	}
	
	public void hello(){
		if(error){
			throw new RuntimeException("error,name="+name);
		}
		System.out.println("hello,name="+name);
	}
	
	public void close() throws Exception{
		System.out.println("close run,name="+name);
	}

}