java - 由于 main 方法不是静态的，编译器错误

Question

我编写了一个程序来将一些文本组装成二进制代码。编译器总是在 main 方法中给出错误，并告诉我它不是静态的......有人可以帮助我吗？？？我试图使其静态，但错误仍然存​​在。我希望有人能帮助我。

public class Main {
     private String file;
     private int pc = 0;

    public  Main( String fin ) {
        file = fin;
    }

    public void main( String[] args ) throws IOException, Exception {
        // CREATE INSTANCES OF OTHER MODULES
        Parser fp = new Parser( args[ 0 ] );
        Parser sp = new Parser( args[ 0 ] );
        Code code = new Code();
        HashMap<String, String> st = new HashMap<String, String>();

        // SYMBOL TABLE INITIALIZATION
        st.put( "R0", "0" ); st.put( "R1", "1" ); st.put( "R2", "2" ); st.put( "R3", "3" ); st.put( "R4", "4" ); st.put( "R5", "5" ); st.put( "R6", "6" ); st.put( "R7", "7" );
        st.put( "R8", "8" ); st.put( "R9", "9" ); st.put( "R10", "10" ); st.put( "R11", "11" ); st.put( "R12", "12" ); st.put( "R13", "13" ); st.put( "R14", "14" ); st.put( "R15", "15" );
        st.put( "SCREEN", "16384" ); st.put( "KBD", "24576" );
        st.put( "SP", "0" ); st.put( "LCL", "1" ); st.put( "ARG", "2" ); st.put( "THIS", "3" ); st.put( "THAT", "4" );

        // FIRST PASS
        fp.advance();
        while( fp.command != null ) {
            if( fp.commandType() == "L_COMMAND" ) {
                st.put( fp.symbol(), Integer.toString( pc ) );
                pc--;
            }
            fp.advance();
            pc++;
        }

        // SECOND PASS
        FileWriter writer = null;
        int rAllocation = 16; // Keeps a record of the last register allocated to a variable.

        try {
            // CREATE FILE, FILE WRITER
            File nf = new File( file.replaceAll( "\\.asm", ".hack" ) );
            nf.createNewFile();
            writer = new FileWriter( nf );

            // SECOND PASS
            sp.advance();
            while( sp.command != null ) {
                if( sp.commandType() == "L_COMMAND" ) {
                    // Do nothing.
                } else if( sp.commandType() == "A_COMMAND" ) {
                    if( !( Pattern.compile( "[a-zA-Z]" ).matcher( sp.symbol() ).find() ) ) { // If the symbol consists of only digits.
                        writer.write( convertAddr( sp.symbol() ) + "\n" ); // Translate integer value to binary, write to file.
                    } else if( st.get( sp.symbol() ) == null ){
                        st.put( sp.symbol(), Integer.toString( rAllocation ) ); // Assign the variable an unoccupied register.
                        rAllocation++;
                        writer.write( convertAddr( st.get( sp.symbol() ) ) + "\n" );  // Retrieve the just allocated value from SymbolTable, translate to binary, write.
                    } else {
                        writer.write( convertAddr( st.get( sp.symbol() ) ) + "\n" );  // Retrieve value of symbol from SymbolTable, translate to binary, write.
                    }
                } else if( sp.commandType() == "C_COMMAND" ) {
                    String d = code.dest( sp.dest() );
                    String c = code.comp( sp.comp() );
                    String j = code.jump( sp.jump() );

                    writer.write( "111" + c + d + j + "\n" );
                }
                sp.advance();
            }
        } catch( IOException e ) {
            e.printStackTrace();
        } finally {
            // CLOSE WRITER
            writer.flush();
            writer.close();
        }
    }

    private String convertAddr( String addr ) throws Exception{
        String bin;
        String zeroPad = "";
        if( addr != null ) {
            bin = Integer.toBinaryString( Integer.parseInt( addr ) );
            for( int i = 0; i < ( 16 - bin.length() ); i++ ) {
                zeroPad += "0";
            }
            return zeroPad + bin;
        } else {
            throw new Exception( "Null Parameter." );
        }
    }
}

还有另外两个类，解析器和代码，与主类相关

Answer 1

你的主要方法需要是

public static void main(String[] args){}

需要静态，因为非静态方法是在类的对象上调用的 - 并且在程序开始时还没有创建对象。然而，静态方法是在类上调用的，这意味着它们可以在类加载后立即调用，但只能访问类的其他静态资源。

这意味着您的 pc 和 file 变量也需要是静态的，或者您需要将代码移动到不同的方法并在 main 中创建一个 Main 对象方法并在新对象上调用该新方法，如下所示:

public class Main(){
    private String file;
    private int pc = 0;

    public Main(String fin){
        file=fin;
    }

    public static void main(String[] args){
        Main main = new Main(args[0]); //or wherever the filename is in args
        main.doStuff();
    }

    public void doStuff(){
        //your code
    }
}