Java Programming: Two-Dimensional
Array
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Objectives
• To describe how a Two-dimensional array is implemented as an array of arrays.
• To understand the structure of Two-dimensional array
• To demonstrate processing Two-Dimensional array with sample code
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Two-Dimensional Array
•
payScaleTable
Declare the pay scale table as:
double [ ][ ] payScaleTable;
Or
double payScaleTable [ ][ ];
• Create the array as:
payScaleTable = new double [4][5];
• A table organized in rows and columns is a
very effective means for communicating
many different types of information.
• In Java, we represent tables as twodimensional arrays.
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2-D Array Implementation
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Understanding Length of payScaleTable
• Expression:
• payScaleTable.length
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Cont’d
• Expression: payScaleTable[1].length
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Accessing an Element
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Two-Dimensional Array Processing: Sample Code
public class Ch10PayScaleTable {
A programmer with skill grade
level 2, step 1 earns $36.50 1hr.
public static void main (String[] args) {
double[ ][ ] payScaleTable = { {10.50, 12.00, 14.50, 16.75, 18.00},
{20.50, 22.25, 24.00, 26.25, 28.00},
This code finds the average
pay of the grade 2
programmers.
{34.00, 36.50, 38.00, 40.35, 43.00},
{50.00, 60.00, 70.00, 80.00, 99.99} };
double sum = 0.0, average;
for(int j = 0; j < 5; j++) {
sum += payScaleTable[2][j];
}
average = sum / 5;
System.out.println("Average of Level 2 Employees: " + average );
System.out.println("\n");
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Cont’d
double difference;
Display the pay difference
at each grade level
for(int i = 0; i < 4; i++) {
difference = payScaleTable[i][4] - payScaleTable[i][0];
System.out.println("Pay difference at Grade Level "+ i + " is " + difference);
}
A programmer with skill grade
level 2, step 1 earns $36.50 1hr.
System.out.println("\n");
for(int i = 0; i < payScaleTable.length; i++) {
for(int j = 0; j < payScaleTable[i].length; j++) {
System.out.print( payScaleTable [i] [j] + " " );
}
System.out.println("");
Display the pay
scale table
} System.out.println("\n");
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Cont’d
for (int i = 0; i < payScaleTable.length; i++) {
for (int j = 0; j < payScaleTable[i].length; j++) {
payScaleTable[i][j] += 1.50;
System.out.print(payScaleTable[i][j] + " " );
}
System.out.println("");
}
}
}
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Summary
• This lesson describes how two-dimensional arrays are used in Java.
• In Java, we represent tables as two-dimensional arrays.
• Two indices (one for the row and another for the column) are used to refer to an
array element in two-dimensional array.
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Let’s Do Exercises!!!
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