大神们什么情况啊 一直说name 是空？

Question

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "String.toCharArray()" because "this.name" is null
    at p.<init>(Demo.java:33)
    at Demo.main(Demo.java:3)

public class Demo {
    public static void main(String [] args){
        p l =new p("  Tupi   ");
        l.i();
        l.x();
        l.s1();
        //System.out.print(l.c+"   "+l.b);
        int e = 0;
        int g = 5;
        char [] a  = {' ','a','b','c','n',' '};
        System.out.print(String.copyValueOf(a,e,g+1));

    }
}


class p{
    private String name;
    p(String name){
        this.name = name;
    }

    public int getC() {
        return c;
    }

    public int getB() {
        return b;
    }

    private int c;
    private int b;
    char [] a  = name.toCharArray();

    public void i() {
        for (int i = 0;i<a.length;i++){
            if (a[i]!=' '){
                c=i;
                break;

            }
        }
    }
    public void x() {
        for (int i = a.length-1;i>0;i--){
            if (a[i]!=' '){
                b=i;
                break;

            }
        }
    }
    public void s1(){
        System.out.println(String.copyValueOf(a,this.getC(),this.getB()));
    }


}

我人都傻掉了 ，设计思路是这样的 我想模拟trim  去空格，我想先传一个字符串进去，然后再用 字符串转字符数组，然后再用字符数组循环去除空格，再用字符数组转换字符串！    

现在问题是 我穿进去一个字符串，为什么说我是null值 搞不懂 我是小白！大神救救孩子吧！！

Answer 1

public class Demo {
    public static void main(String [] args){
        p l =new p();
        l.str_char("  Tupi   ");
        l.i();
        l.x();
        l.s1();
        //System.out.print(l.c+"   "+l.b);
        int e = 0;
        int g = 5;
        char [] a  = {' ','a','b','c','n',' '};
        System.out.print(String.copyValueOf(a,e,g+1));
 
    }
}
 
 
class p{
    //private String name;
    char[] a;
    
    public void str_char(String name) {
    	a = name.toCharArray();;
    }
 
    public int getC() {
        return c;
    }
 
    public int getB() {
        return b;
    }
 
    private int c;
    private int b;
    
 
    public void i() {
        for (int i = 0;i<a.length;i++){
            if (a[i]!=' '){
                c=i;
                break;
 
            }
        }
    }
    public void x() {
        for (int i = a.length-1;i>0;i--){
            if (a[i]!=' '){
                b=i;
                break;
 
            }
        }
    }
    public void s1(){
        System.out.println(String.copyValueOf(a,this.getC(),this.getB()));
    }
}

或者这样子吧