解决不了的文件压缩有关问题！想了老半天了！请大家赐小弟我力量！先谢大家了…

解决不了的文件压缩问题！想了老半天了！请大家赐我力量！先谢大家了……
运行结果：请输入需要压缩的第1文件的文件名:
a.txt
Exception in thread "main" java.lang.NullPointerException
at Zip.zip(Zip.java:19)
at Main.main(Main.java:8)
是否还需要输入文件？yes/no
不知道怎么解决了请高手指点。。谢谢。。
源代码：
//功能函数
import java.io.*;
import java.util.zip.*;

public class Zip {

void zip() throws IOException{

BufferedReader in1;
in1 = new BufferedReader(new InputStreamReader(System.in));
String cs = null;
String[] file;
int i = 0;
do {
System.out.println("请输入需要压缩的第"+(i+1)+"文件的文件名:");
file=new String[i+1];
file[i]=in1.readLine();
i++;
System.out.println("是否还需要输入文件？yes/no");
} while (cs.equals("yes"));
in1.close();

ZipOutputStream out1;
out1 = new ZipOutputStream(new BufferedOutputStream(new FileOutputStream("b.zip")));
for (int j = 0; j <file.length; j++) {
BufferedInputStream in2;
in2 = new BufferedInputStream(new FileInputStream(file[j]));
out1.putNextEntry(new ZipEntry(file[j]));
int c = 0;
while ((c = in2.read()) != -1) {
out1.write(c);
}

in2.close();
}

out1.close();
}
}

//主函数
import java.io.IOException;

public class Main {
public static void main(String[] args) throws IOException {

Zip zp = new Zip();
zp.zip();

}
}

------解决方案--------------------
你的：
do {
System.out.println("请输入需要压缩的第"+(i+1)+"文件的文件名:");
file=new String[i+1];file[i]=in1.readLine();
i++;
System.out.println("是否还需要输入文件？yes/no");
} while (cs.equals("yes"));
in1.close();

是不对的，
其实到循环结束，你只读到了最后一个文件，而且数组的前几项都是空的，
在后面压缩的时候肯定会包空指针异常
------解决方案--------------------

Java code


 void zip() {
        BufferedReader in1=new BufferedReader(new InputStreamReader(System.in));
        String[] file=null;
        try {
            System.out.print("请输入压缩包数量：");
            int sum=Integer.parseInt(in1.readLine());
            file = new String[sum];
            int i = 0;
            do {
                System.out.println("请输入需要压缩的第"+(i+1)+"文件的文件名:");
                file[i]=in1.readLine();
                i++;
                } while (i<=sum-1);
        } catch (IOException e) {
            e.printStackTrace();
        }
        finally{
            try {
                if(null!=in1){
                    in1.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        ZipOutputStream out1 = null;
        BufferedInputStream in2 = null;
        try {
            for (int j = 0; j <file.length; j++) {
                out1 = new ZipOutputStream(new BufferedOutputStream(new FileOutputStream(file[j]+j+"_b.zip")));
                in2 = new BufferedInputStream(new FileInputStream(file[j]));
                byte[] temp=new byte[in2.available()];
                out1.putNextEntry(new ZipEntry(file[j]));
                in2.read(temp);
                out1.write(temp);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        finally{
            try {
                if(null!=in2){
                    in2.close();
                }
                if(null!=out1){
                    out1.close();
                }
                System.out.println("文件另外压缩复制完成！");
            } catch (IOException e) {
                e.printStackTrace();
            }
            
        }
    }

解决不了的文件压缩有关问题！想了老半天了！请大家赐小弟我力量！先谢大家了…

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