转到Java中for语句的开头

Question

I'm very new to Java and maybe my question is a bit irritating.

I have two for loops in my code and I want to go to the beginning of each one by a for - else statement.

public static void main(String[] args)
{
    int[][] x=new int[1000][1000];

    int[] Z=new int[1000];

    lable1:
        for(int i=1; i<=1000; i++)
        {
            Z[i]=rand1.nextInt(1000);
            System.out.println("Z["+i +"] = " + Z[i] );

            if(Z[i]>0 && Z[i]<=Nk)
            {
                int Z1=Z[i]-1;
                lable2:         
                    for(int j = 1; j<=Z1;j++ )
                    {
                        x[i][j]= rand2.nextInt(1000);
                        sum+=x[i][j];
                        if( sum<1000)
                        {
                            x[i][(j+1)]=1000-sum;
                            System.out.println("x[" + i+"][" + j + "] = " + x[i][j]);
                            System.out.println("Nx[" + i+"][" + (j+1) + "] = " +x[i][(j+1)]);
                        }
                        else{
                            // ????
                            //Goto lable2;
                        }
                    }
            }
            else{
                //goto label1;
                // ????
            } 
        }

}

Answer 1

You can break to any defined label (within scope) by using:

break label;

Same holds for continue .

Here is something to read.

In your particular example, removing the else s would do what you want.

Answer 2

Just use continue keyword.. It will continue with the next iteration.. No need to label your loop .. As you are not continuing the outer loop from the inner one.. Or, if you want to continue with outer loop, you can use continue with a label ...

And you should use your for loop from j = 0 to j < z1 ..

for(int j = 0; j < Z1;j++ ) {    
      if( sum<1000) {
           x[i][(j+1)]=1000-sum;
           System.out.println("x[" + i+"][" + j + "] = " + x[i][j]);
           System.out.println("Nx[" + i+"][" + (j+1) + "] = " +x[i][(j+1)]);
       }
       else{  // Not needed if your else does not contain anything else..
           continue;
       }
}

In fact you don't need an else block at all.. If you are not doing any further processing in it..

Just remove it.. It will automatically go to your loop..

Suggestion : - You should use coding convention.. variable names start with lowercase letter or underscore .. (Z1 -> z1)

Answer 3

Here you are:

public static void main(String[] args) {
        int[][] x = new int[1000][1000];

        int[] Z = new int[1000];

        boolean resetOuterCycle = true;

        for (int i = 0; i < 1000; i++) {
            Z[i] = rand1.nextInt(1000);
            System.out.println("Z[" + i + "] = " + Z[i]);

            if (Z[i] > 0 && Z[i] <= Nk) {
                int Z1 = Z[i] - 1;

                boolean resetInnerCycle = true;

                for (int j = 0; j < Z1; j++) {
                    x[i][j] = rand2.nextInt(1000);
                    sum += x[i][j];
                    if (sum < 1000) {
                        x[i][(j + 1)] = 1000 - sum;
                        System.out.println("x[" + i + "][" + j + "] = " + x[i][j]);
                        System.out.println("Nx[" + i + "][" + (j + 1) + "] = " + x[i][(j + 1)]);
                    } else if (resetInnerCycle) {
                        j = 0;
                        resetInnerCycle = false;
                    }
                }
            } else if (resetOuterCycle) {
                i = 0;
                resetOuterCycle = false;
            }
        }

    }

Answer 4

- In your above code you can use 2 approach to do it...

1st Approach : No else part

for (int i = 0; i < 1000; i++) {

   if (Z[i] > 0 && Z[i] <= Nk){
    for (int j = 0; j < Z1; j++) {

          if(sum < 1000){


         }
      }
    }
  }

2nd Approach : With else part and continue

for (int i = 0; i < 1000; i++) {

   if (Z[i] > 0 && Z[i] <= Nk){

    for (int j = 0; j < Z1; j++) {

              if(sum < 1000){


             }else{

                  continue;

             }
          }
       }else{

               continue;

        }
   }