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Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
Md05 arrays
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Md05 arrays

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  • 1. Module 5 Arrays  
  • 2.  
  • 3. <ul><li> Arrays </li></ul><ul><ul><li>• Java array is an ordered collection of primitives, </li></ul></ul><ul><ul><li>object references, or other arrays. </li></ul></ul><ul><ul><li>• A structure that holds multiple values of </li></ul></ul><ul><ul><li>the same type. </li></ul></ul><ul><ul><li>• An array is an object; it is created with new </li></ul></ul>
  • 4. <ul><ul><li>To create an array follow three steps </li></ul></ul><ul><ul><ul><li>Declaration </li></ul></ul></ul><ul><ul><ul><li>Construction </li></ul></ul></ul><ul><ul><ul><li>Initialization </li></ul></ul></ul>
  • 5. <ul><ul><li>Declaration </li></ul></ul><ul><ul><li>Declaration tell the array’s name and what type its </li></ul></ul><ul><ul><li>element will be. </li></ul></ul><ul><ul><li>int[]ints; //declare array of primitive types </li></ul></ul><ul><ul><li>double[] dubs; </li></ul></ul><ul><ul><li>Dimension[] dims; //declare array of object reference </li></ul></ul><ul><ul><li>Float[][]twodee; //declare a two dimensional array </li></ul></ul>
  • 6. <ul><li>Construction </li></ul><ul><ul><li>Notice the declaration doesnot specify the size of array, </li></ul></ul><ul><ul><li>size is specified at runtime when array is allocated </li></ul></ul><ul><ul><li>via new keyword . </li></ul></ul><ul><ul><li>int[] ints; </li></ul></ul><ul><ul><li>ints=new int[25]; </li></ul></ul><ul><ul><li>Use the new keyword to create an array object. </li></ul></ul>
  • 7. <ul><ul><li>Declaration and construction performed in single </li></ul></ul><ul><ul><li>line as </li></ul></ul><ul><ul><li>int[] ints=new int[25]; </li></ul></ul>
  • 8. <ul><ul><li>Initialization </li></ul></ul><ul><ul><li>When the array is constructed its elements are </li></ul></ul><ul><ul><li>automatically initialized to their default value </li></ul></ul><ul><ul><li>Element type Initial Value </li></ul></ul><ul><ul><li>byte 0 </li></ul></ul><ul><ul><li>short 0 </li></ul></ul><ul><ul><li>i nt 0 </li></ul></ul><ul><ul><li>long 0L </li></ul></ul><ul><ul><li>float 0.0f </li></ul></ul><ul><ul><li>double 0.0d </li></ul></ul><ul><ul><li>char ‘u0000’ </li></ul></ul><ul><ul><li>b oolean false </li></ul></ul><ul><ul><li>object reference null </li></ul></ul>
  • 9. <ul><li>T o initialize an array to values other than above </li></ul><ul><ul><li>combine declaration,construction and initialization </li></ul></ul><ul><ul><li>into single step . </li></ul></ul><ul><ul><li>Implicit assigning of values </li></ul></ul><ul><ul><ul><li>boolean[] answers = { true, false, true, true, false }; </li></ul></ul></ul><ul><ul><ul><li>float[]diameters={1.1f,2.2f,3.3f,4.4f,5.5f};  </li></ul></ul></ul><ul><ul><li>Explicit assigning of values </li></ul></ul><ul><ul><ul><li>long[] squares; </li></ul></ul></ul><ul><ul><ul><li>squares=new long[6000]; </li></ul></ul></ul><ul><ul><ul><li>for(int i=0;i&lt;6000;i++){ </li></ul></ul></ul><ul><ul><ul><li>squares[i]=i*i; </li></ul></ul></ul><ul><ul><ul><li>} </li></ul></ul></ul>
  • 10. <ul><ul><ul><li>Accessing an Array Element </li></ul></ul></ul><ul><ul><ul><li>for (int i = 0; i &lt; anArray.length; i++) { </li></ul></ul></ul><ul><ul><ul><li>anArray[i] = i; </li></ul></ul></ul><ul><ul><ul><li>System.out.print(anArray[i] + &amp;quot; &amp;quot;); </li></ul></ul></ul><ul><ul><ul><li>  } </li></ul></ul></ul><ul><li>  </li></ul><ul><li>Note: Java array’s index always start at 0. </li></ul>
  • 11. <ul><li>Getting the Size of an Array </li></ul><ul><li>arrayname.length </li></ul><ul><ul><ul><li>Note :length is not a method. length is a property </li></ul></ul></ul><ul><ul><ul><li>provided by the Java platform for all arrays. </li></ul></ul></ul>
  • 12. &nbsp;
  • 13. Example ArrayOfArraysDemo
  • 14. <ul><li> Array Bounds </li></ul><ul><ul><li>All array subscripts begin at 0: </li></ul></ul><ul><ul><ul><ul><li>int list[] = new int [10]; </li></ul></ul></ul></ul><ul><ul><ul><ul><li>for (int i = 0; i &lt; list.length; i++) { </li></ul></ul></ul></ul><ul><ul><ul><ul><li>System.out.println(list[i]); </li></ul></ul></ul></ul><ul><ul><ul><ul><li>} </li></ul></ul></ul></ul>
  • 15. <ul><li> Array Resizing </li></ul><ul><ul><li>• Cannot resize an array </li></ul></ul><ul><ul><li>• Can use the same reference variable to refer to an </li></ul></ul><ul><ul><li>entirely new array: </li></ul></ul><ul><ul><li>int elements[] = new int[6]; elements = new int[10]; </li></ul></ul><ul><ul><li>Example ArrayDemo.java </li></ul></ul>
  • 16. Example ArrayCopyDemo

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