数组“

src/main/java/examples/Array/MainClass.java

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+package examples.Array;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+
+public class MainClass {
+
+    public static void main(String[] args) throws Exception {
+        int array[] = {2, 5, -2, 6, -3, 8, 0, -7, -9, 4 };
+        Arrays.sort(array);
+        printArray("排序结果为：", array);
+        int index = Arrays.binarySearch(array, 2);
+        System.out.println("元素 2  在第 " + index + " 个位置");
+
+        //插入数组
+        int newIndex = index;
+        array = insertElement(array, 1, newIndex);
+        printArray("数组添加元素 1", array);
+
+        //数组长度
+        String[][] data = new String[2][5];
+        System.out.println("第一维数组长度: " + data.length);
+        System.out.println("第二维数组长度: " + data[0].length);
+
+        //数组反转
+        ArrayList<String> arrayList = new ArrayList<String>();
+        arrayList.add("A");
+        arrayList.add("B");
+        arrayList.add("C");
+        Collections.reverse(arrayList);
+        System.out.println("反转后排序：" + arrayList);
+
+
+        //获取最大值、最小值
+        Integer[] numbers = { 8, 2, 7, 1, 4, 9, 5 };
+        int min = (int) Collections.min(Arrays.asList(numbers));
+        int max = (int) Collections.max(Arrays.asList(numbers));
+        System.out.println("最小值：" + min);
+        System.out.println("最大值：" + max);
+
+
+        //数组合并
+        String a[] = { "A", "E", "I" };
+        String b[] = { "O", "U" };
+
+
+
+    }
+
+    private static void printArray(String message, int array[]) {
+        System.out.println(message
+                + ": [length: " + array.length + "]");
+        for (int i = 0; i < array.length; i++) {
+            if(i != 0){
+                System.out.print(", ");
+            }
+            System.out.print(array[i]);
+        }
+        System.out.println();
+    }
+
+    private static int[] insertElement(int original[],
+                                       int element, int index) {
+        int length = original.length;
+        int destination[] = new int[length + 1];
+        System.arraycopy(original, 0, destination, 0, index);
+        destination[index] = element;
+        System.arraycopy(original, index, destination, index
+                + 1, length - index);
+        return destination;
+    }
+
+}

src/main/java/examples/String/JavaStringSplitEmp.java

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+public class JavaStringSplitEmp {
+    public static void main(String args[]){
+
+        String str = "www-runoob-com";
+        String[] temp;
+        String delimeter = "-";  // 指定分割字符
+        temp = str.split(delimeter); // 分割字符串
+        // 普通 for 循环
+        for(int i =0; i < temp.length ; i++){
+            System.out.println(temp[i]);
+            System.out.println("");
+        }
+
+        System.out.println("------java for each循环输出的方法-----");
+        String str1 = "www.runoob.com";
+        String[] temp1;
+        String delimeter1 = "\\.";  // 指定分割字符， . 号需要转义
+        temp1 = str1.split(delimeter1); // 分割字符串
+        for(String x :  temp1){
+            System.out.println(x);
+            System.out.println("");
+        }
+    }
+}

src/main/java/examples/String/JavaStringSplitEmp2.java

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+package examples.String;
+
+import java.util.StringTokenizer;
+
+public class JavaStringSplitEmp2 {
+    public static void main(String[] args) {
+
+        String str = "This is String , split by StringTokenizer, created by runoob";
+        StringTokenizer st = new StringTokenizer(str);
+
+        System.out.println("----- 通过空格分隔 ------");
+        while (st.hasMoreElements()) {
+            System.out.println(st.nextElement());
+        }
+
+        System.out.println("----- 通过逗号分隔 ------");
+        StringTokenizer st2 = new StringTokenizer(str, ",");
+
+        while (st2.hasMoreElements()) {
+            System.out.println(st2.nextElement());
+        }
+    }
+}

src/main/java/examples/String/Main.java

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+public class Main {
+    public static void main(String args[]) {
+        String str = "this is Java";
+        System.out.println(removeCharAt(str, 3));
+    }
+    public static String removeCharAt(String s, int pos) {
+        return s.substring(0, pos) + s.substring(pos + 1);
+    }
+}

src/main/java/examples/String/SearchStringEmp.java

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+public class SearchStringEmp {
+    public static void main(String[] args) {
+        String strOrig = "Google Runoob Taobao";
+        int intIndex = strOrig.indexOf("Runoob");
+        if(intIndex == - 1){
+            System.out.println("没有找到字符串 Runoob");
+        }else{
+            System.out.println("Runoob 字符串位置 " + intIndex);
+        }
+    }
+}

src/main/java/examples/String/SearchlastString.java

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+public class SearchlastString {
+    public static void main(String[] args) {
+        String strOrig = "Hello world ,Hello Runoob";
+        int lastIndex = strOrig.lastIndexOf("Runoob");
+        if(lastIndex == - 1){
+            System.out.println("没有找到字符串 Runoob");
+        }else{
+            System.out.println("Runoob 字符串最后出现的位置： "+ lastIndex);
+        }
+    }
+}

src/main/java/examples/String/StringCompareEmp.java

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+package examples.String;
+
+public class StringCompareEmp {
+
+    public static void main(String[] args) {
+        String str = "Hello world";
+        String anotherString = "Hello world";
+        Object objStr = str;
+
+        // 以下实例中我们通过字符串函数
+        // compareTo (string) ，
+        // compareToIgnoreCase(String)
+        // 及 compareTo(object string) 来比较两个字符串，
+        // 并返回字符串中第一个字母ASCII的差值。
+        System.out.println(str.compareTo(anotherString));
+        System.out.println(str.compareToIgnoreCase(anotherString));
+        System.out.println(str.compareTo(objStr.toString()));
+    }
+
+}

src/main/java/examples/String/StringComparePerformance.java

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+public class StringComparePerformance{
+    public static void main(String[] args){
+        long startTime = System.currentTimeMillis();
+        for(int i=0;i<50000;i++){
+            String s1 = "hello";
+            String s2 = "hello";
+        }
+        long endTime = System.currentTimeMillis();
+        System.out.println("通过 String 关键词创建字符串"
+                + " : "+ (endTime - startTime)
+                + " 毫秒" );
+        long startTime1 = System.currentTimeMillis();
+        for(int i=0;i<50000;i++){
+            String s3 = new String("hello");
+            String s4 = new String("hello");
+        }
+        long endTime1 = System.currentTimeMillis();
+        System.out.println("通过 String 对象创建字符串"
+                + " : " + (endTime1 - startTime1)
+                + " 毫秒");
+    }
+}

src/main/java/examples/String/StringConcatenate.java

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+public class StringConcatenate {
+    public static void main(String[] args){
+
+
+        long startTime = System.currentTimeMillis();
+        for(int i=0;i<5000;i++){
+            String result = "This is"
+                    + "testing the"
+                    + "difference"+ "between"
+                    + "String"+ "and"+ "StringBuffer";
+        }
+        long endTime = System.currentTimeMillis();
+        System.out.println("字符串连接"
+                + " - 使用 + 操作符 : "
+                + (endTime - startTime)+ " ms");
+
+
+        long startTime1 = System.currentTimeMillis();
+        for(int i=0;i<5000;i++){
+            StringBuffer result = new StringBuffer();
+            result.append("This is");
+            result.append("testing the");
+            result.append("difference");
+            result.append("between");
+            result.append("String");
+            result.append("and");
+            result.append("StringBuffer");
+        }
+        long endTime1 = System.currentTimeMillis();
+        System.out.println("字符串连接"
+                + " - 使用 StringBuffer : "
+                + (endTime1 - startTime1)+ " ms");
+    }
+}

src/main/java/examples/String/StringFormat.java

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+import java.util.*;
+
+public class StringFormat {
+    public static void main(String[] args){
+        double e = Math.E;
+        System.out.format("%f%n", e);
+        System.out.format(Locale.CHINA  , "%-10.4f%n%n", e);  //指定本地为中国（CHINA）
+    }
+}

src/main/java/examples/String/StringOptimization.java

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+public class StringOptimization {
+    public static void main(String[] args){
+        String variables[] = new String[50000];
+
+
+        for( int i=0;i <50000;i++){
+            variables[i] = "s"+i;
+        }
+        long startTime0 = System.currentTimeMillis();
+        for(int i=0;i<50000;i++){
+            variables[i] = "hello";
+        }
+        long endTime0 = System.currentTimeMillis();
+        System.out.println("直接使用字符串： "+ (endTime0 - startTime0)  + " ms" );
+
+
+        long startTime1 = System.currentTimeMillis();
+        for(int i=0;i<50000;i++){
+            variables[i] = new String("hello");
+        }
+        long endTime1 = System.currentTimeMillis();
+        System.out.println("使用 new 关键字：" + (endTime1 - startTime1) + " ms");
+
+
+
+        long startTime2 = System.currentTimeMillis();
+        for(int i=0;i<50000;i++){
+            variables[i] = new String("hello");
+            variables[i] = variables[i].intern();
+        }
+        long endTime2 = System.currentTimeMillis();
+        System.out.println("使用字符串对象的 intern() 方法: "
+                + (endTime2 - startTime2)
+                + " ms");
+    }
+}

src/main/java/examples/String/StringRegionMatch.java

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+public class StringRegionMatch{
+    public static void main(String[] args){
+        String first_str = "Welcome to Microsoft";
+        String second_str = "I work with microsoft";
+        boolean match1 = first_str.
+                regionMatches(11, second_str, 12, 9);
+        boolean match2 = first_str.
+                regionMatches(true, 11, second_str, 12, 9); //第一个参数 true 表示忽略大小写区别
+        System.out.println("区分大小写返回值：" + match1);
+        System.out.println("不区分大小写返回值：" + match2);
+    }
+}

src/main/java/examples/String/StringReplaceEmp.java

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+public class StringReplaceEmp{
+    public static void main(String args[]){
+        String str="Hello World";
+        System.out.println( str.replace( 'H','W' ) );
+        System.out.println( str.replaceFirst("He", "Wa") );
+        System.out.println( str.replaceAll("He", "Ha") );
+    }
+}

src/main/java/examples/String/StringReverseExample.java

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+public class StringReverseExample{
+    public static void main(String[] args){
+        String string="runoob";
+        String reverse = new StringBuffer(string).reverse().toString();
+        System.out.println("字符串反转前:"+string);
+        System.out.println("字符串反转后:"+reverse);
+    }
+}

src/main/java/examples/String/StringToUpperCaseEmp.java

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+public class StringToUpperCaseEmp {
+    public static void main(String[] args) {
+        String str = "string runoob";
+        String strUpper = str.toUpperCase();
+        System.out.println("原始字符串: " + str);
+        System.out.println("转换为大写: " + strUpper);
+    }
+}