我无法弄清楚这种void方法是如何工作的

My code is:

我的代码是:

public class MyProgram {
    public void start() {
        int a = 1; 
        int[] b = { 1, 2, 3}; 
        int[] c = { 1, 2, 3}; 

        method1(a,  b[0], c); 

        System.out.println("a   = " + a); 
        System.out.println("b[0]   = " + b[0]); 
        System.out.println("c[0]   = " + c[0]); 
    }

    private  void method1(int x, int y, int[] z) {
        x++; 
        y = 10; 

        if ( z.length >= 1   ) {  
            z[0] = 100;  
        }
        System.out.println(x); 
        System.out.println(y); 
    }
}
public class MyProgram {