I Dont know how to put my data into 2D arrays

[okokok]

the first 4 characters into array.
and every row has same ordered number.
like:
String a = "7890100"
7->0,0
8->0,1
9->0,2
0->0,3

7->1,0
8->1,1
9->1,2
0->1,3

7->2,0
8->2,1
9->2,2
0->2,3

7->3,0
8->3,1
9->3,2
0->3,3

[Norm]

So the index for the characters of the source String would go from 0 to 3.

[okokok]

Yes, a.substring(0,3)

So the index for the characters of the source String would go from 0 to 3.

[Norm]

I was referring to this index:
java.lang.StringIndexOutOfBoundsException: String index out of range: 5

[okokok]

what's mean?

So the index for the characters of the source String would go from 0 to 3.

[Norm]

Where is this error happening?
java.lang.StringIndexOutOfBoundsException: String index out of range: 5

The index is past the end of the String. Your code must keep the index within the length of the String.

[okokok]

I know that, the b1 string index out of range. because the 'begin'and'end' dont stop adding 1
until the all loop is done.

I was referring to this index:
java.lang.StringIndexOutOfBoundsException: String index out of range: 5

[Norm]

Your code must keep the value of begin in bounds.

[okokok]

when the begin = 4,and 5 , the b1 is out of range. thanks!!! But i still confused how to reset 'begin''end' to initial value

I know that, the b1 string index out of range. because the 'begin'and'end' dont stop adding 1
until the all loop is done.

[Norm]

Use an if statement

[okokok]

I revise the code.

import java.lang.*;


public class TwoD {

public static void main(String[] args) {
int begin=0;
int end=1;
String a = new String("1111100");

String b1 = a.substring(0,4);

String b2 = a.substring(4, 7);

System.out.println(b1);
System.out.println(b2);

String[][] arrayB= new String[3][4];;
for(int i=0; i<=2;i++)
{
for(int j=0;j<=3;j++)
{
System.out.println("i="+i);
System.out.println("j="+j);
System.out.println("beginInput="+begin);
System.out.println("endInput="+end);

arrayB[i][j]=b1.substring(begin,end);
begin++;
end++;


System.out.println("begin="+begin);
System.out.println("end="+end);

if (begin>3&&end>4)
{
begin =0;
end = 1;
}

}
}

}

}

The output:1111
100
i=0
j=0
beginInput=0
endInput=1
begin=1
end=2
i=0
j=1
beginInput=1
endInput=2
begin=2
end=3
i=0
j=2
beginInput=2
endInput=3
begin=3
end=4
i=0
j=3
beginInput=3
endInput=4
begin=4
end=5
i=1
j=0
beginInput=0
endInput=1
begin=1
end=2
i=1
j=1
beginInput=1
endInput=2
begin=2
end=3
i=1
j=2
beginInput=2
endInput=3
begin=3
end=4
i=1
j=3
beginInput=3
endInput=4
begin=4
end=5
i=2
j=0
beginInput=0
endInput=1
begin=1
end=2
i=2
j=1
beginInput=1
endInput=2
begin=2
end=3
i=2
j=2
beginInput=2
endInput=3
begin=3
end=4
i=2
j=3
beginInput=3
endInput=4
begin=4
end=5



cool!!!! I have a conclude that you must know the nature of error, then you can fix the error completely.
Thanks, Norm!

Your code must keep the value of begin in bounds.

[Norm]

You could reduce the code a bit by getting rid of the end variable since it is always = begin+1

arrayB[i][j]=b1.substring(begin, begin+1);

I changed your debug output to:

		System.out.println("i="+ i + ", j="+j + " char=" + arrayB[i][j]);
		System.out.println("begin= "+begin);