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OneCodeOneTimeOneCodeOneTime
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Chapter 16 arrays btp170603 (#5)
* 170537-Generic * 0528-Generic * Chapter-15-Generic-btp0530 * Chapter-16-Arrays-btp170603
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8 files changed

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‎src/btp/oneP/ArrayOfGenerics.java‎

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package btp.oneP;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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public class ArrayOfGenerics {
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public static void main(String[] args) {
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//编译期不能实例化泛型数组，但是可以创建泛型数组的引用
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List<String>[] ls;
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List[] la = new List[10];
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ls = (List<String>[])la;
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ls[0] = new ArrayList<String>(Arrays.asList("hehe","keke","xixi"));
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//ls[1] = new ArrayList<Integer>();
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Object[] objects = ls;
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objects[1] = new ArrayList<Integer>(Arrays.asList(1,2,3,4,5));
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System.out.println(Arrays.toString(la));
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System.out.println(la.getClass().getName());
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System.out.println(Arrays.toString(ls));
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System.out.println(ls.getClass().getName());
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System.out.println(Arrays.toString(objects));
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System.out.println(objects.getClass().getName());
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List<BerylliumSphere>[] spheres = (List<BerylliumSphere>[])new List[10];
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for(int i=0;i<10;i++){
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spheres[i] = new ArrayList<BerylliumSphere>();
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}
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}
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}

‎src/btp/oneP/ArrayOptions.java‎

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package btp.oneP;
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import java.util.Arrays;
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public class ArrayOptions {
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public static void main(String[] args) {
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BerylliumSphere[] a = null;
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BerylliumSphere[] b = new BerylliumSphere[5];
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System.out.println(a);
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System.out.println(b);
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System.out.println(Arrays.toString(b));
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BerylliumSphere[] c = new BerylliumSphere[4];
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for(int i=0;i<c.length;i++){
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if(null == c[i]){
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c[i] = new BerylliumSphere();
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}
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}
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BerylliumSphere[] d = {
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new BerylliumSphere(),new BerylliumSphere(),new BerylliumSphere()
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};
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a = new BerylliumSphere[]{
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new BerylliumSphere(),new BerylliumSphere(),new BerylliumSphere()
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};
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System.out.println("a.length:"+a.length);
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System.out.println("b.length:"+b.length);
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System.out.println("c.length:"+c.length);
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System.out.println("d.length:"+d.length);
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a = d;
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System.out.println("a.length:"+a.length);
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int[] e;
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int[] f = new int[4];
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System.out.println("f:"+Arrays.toString(f));
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int[] g = new int[4];
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for(int i=0;i<g.length;i++){
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g[i] = i*i;
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}
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int[] h = {11,47,93};
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System.out.println("f.length:"+f.length);
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System.out.println("g.length:"+g.length);
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System.out.println("h.length:"+h.length);
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e = h;
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System.out.println("e.length:"+e.length);
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e = new int[]{1,2};
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System.out.println("e.length:"+e.length);
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char[] cs = new char[5];
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System.out.println(Arrays.toString(cs));
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}
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}

‎src/btp/oneP/ArrayTest.java‎

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package btp.oneP;
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public class ArrayTest {
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public static void main(String[] args) {
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//f({1,2,3});
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f(new int[]{1,2,3});
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}
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static void f(int[] a){
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for(int i:a){
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System.out.println(i);
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}
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}
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}

‎src/btp/oneP/ContainerComparison.java‎

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package btp.oneP;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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public class ContainerComparison {
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public static void main(String[] args) {
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BerylliumSphere[] spheres = new BerylliumSphere[10];
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for(int i=0;i<5;i++){
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spheres[i] = new BerylliumSphere();
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}
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System.out.println(Arrays.toString(spheres));
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System.out.println(spheres[4]);
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List<BerylliumSphere> sphereList = new ArrayList<BerylliumSphere>();
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for(int i=0;i<5;i++){
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sphereList.add(new BerylliumSphere());
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}
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System.out.println(sphereList);
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System.out.println(sphereList.get(4));
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int[] integers = {0,1,2,3,4,5};
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System.out.println(integers);
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System.out.println(integers[4]);
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List<Integer> intList = new ArrayList<Integer>(Arrays.asList(0,1,2,3,4,5));
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intList.add(97);
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System.out.println(intList);
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System.out.println(intList.get(4));
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}
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}
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class BerylliumSphere{
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private static long counter;
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private final long id = counter++;
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public String toString(){
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return "Sphere"+id;
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}
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}

‎src/btp/oneP/IceCream.java‎

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package btp.oneP;
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import java.util.Arrays;
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import java.util.Random;
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public class IceCream {
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private static Random rand = new Random(47);
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static final String[] FLAVORS = {
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"Chocolate","Strawberry","Vanilla","Mint Chip",
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"Mocha Almond Fudge","Rum Raisin","Praline","Mud"
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};
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public static String[] flavorSet(int n){
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if(n>FLAVORS.length){
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throw new IllegalArgumentException("Set too big");
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}
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String[] results = new String[n];
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boolean[] picked = new boolean[FLAVORS.length];
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for(int i=0;i<n;i++){
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int t;
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do
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t = rand.nextInt(FLAVORS.length);
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while(picked[t]);
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results[i] = FLAVORS[t];
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picked[t] = true;
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}
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return results;
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}
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public static void main(String[] args) {
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for(int i=0;i<7;i++){
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System.out.println(Arrays.toString(flavorSet(3)));
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}
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}
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}

‎src/btp/oneP/MultidimensionalPrimitiveArray.java‎

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package btp.oneP;
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import java.util.Arrays;
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public class MultidimensionalPrimitiveArray {
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public static void main(String[] args) {
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int[][] a = {{1,2,3},{4,5,6}};
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System.out.println(Arrays.toString(a));
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System.out.println(Arrays.toString(a[1]));
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System.out.println(Arrays.deepToString(a));
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}
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}

‎src/btp/oneP/ParameterizedArrayType.java‎

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package btp.oneP;
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import java.util.Arrays;
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public class ParameterizedArrayType {
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public static void main(String[] args) {
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Integer[] ints = {1,2,3,4,5};
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Double[] doubles = {1.1,2.2,3.3,4.4,5.5};
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Integer[] ints2 = new ClassParameter<Integer>().f(ints);
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System.out.println(Arrays.toString(ints2));
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System.out.println(ints == ints2);
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Double[] doubles2 = new ClassParameter<Double>().f(doubles);
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System.out.println(Arrays.toString(doubles2));
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ints = MethodParameter.f(ints);
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System.out.println(Arrays.toString(ints));
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doubles = MethodParameter.f(doubles);
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}
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}
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class ClassParameter<T>{
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public T[] f(T[] args){
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return args;
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}
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}
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class MethodParameter{
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public static <T> T[] f(T[] arg){
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return arg;
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}
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}

‎src/btp/oneP/ThreeWithNew.java‎

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package btp.oneP;
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import java.util.Arrays;
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public class ThreeWithNew {
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public static void main(String[] args) {
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int[][][] a = new int[2][2][4];
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System.out.println(a);
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System.out.println(Arrays.toString(a));
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System.out.println("a.length:"+a.length);
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System.out.println(Arrays.toString(a[0]));
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System.out.println("a[0].length:"+a[0].length);
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System.out.println(Arrays.toString(a[1]));
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System.out.println("a[1].length:"+a[1].length);
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System.out.println(Arrays.toString(a[0][1]));
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}
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}

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