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‎JavaCode/String/StringBufferBuilderTest.java‎

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package String;
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import org.junit.Test;
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public class StringBufferBuilderTest {
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@Test
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public void test2(){
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StringBuffer str1 = new StringBuffer("abc");
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str1.append(1);
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str1.append('1');
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System.out.println(str1);
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//System.out.println(str1.delete(2, 4));
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//System.out.println(str1.replace(2, 4, "hello"));
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//System.out.println(str1.insert(2, false));
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//反转
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str1.reverse();
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System.out.println(str1);
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}
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@Test
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public void test1(){
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StringBuffer sb1 = new StringBuffer("abc");
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sb1.setCharAt(0,'m');
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System.out.println(sb1);//mbc
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StringBuffer sb2 = new StringBuffer();
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System.out.println(sb2.length());//0
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}
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}

‎JavaCode/String/StringDemo.java‎

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package String;
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//将一个字符串进行反转，将字符串中指定部分进行反转，比如"abcdefg"转换为"abfedcg"
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import org.junit.Test;
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public class StringDemo {
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//方法一：将字符串转换为字符数组
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public String reverse1(String str,int startIndex,int endIndex){
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if(str != null){
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char[] charArray = str.toCharArray();
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for(int x = startIndex,y = endIndex;x < y;x++,y--){
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char temp = charArray[x];
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charArray[x] = charArray[y];
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charArray[y] = temp;
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}
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return new String(charArray);
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}else{
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return null;
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}
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}
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//方法二：使用字符串拼接
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public String reverse2(String str,int startIndex,int endIndex){
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String startString = str.substring(0,startIndex);
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for(int i = endIndex;i >= startIndex;i--){
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startString += str.charAt(i);
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}
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startString += str.substring(endIndex + 1);
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return startString;
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}
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//方法三：使用StringBuilder或者StringBuffer来替代String
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public String reverse3(String str,int startIndex,int endIndex){
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StringBuilder builder = new StringBuilder(str.length());
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builder.append(str.substring(0,startIndex));
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for (int i = endIndex; i >= startIndex ; i--) {
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builder.append(str.charAt(i));
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}
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builder.append(str.substring(endIndex + 1));
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return new String(builder);
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}
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@Test
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public void test(){
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String str = "abcdefg";
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System.out.println(reverse3(str, 2, 5));
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}
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}

‎JavaCode/String/StringDemo1.java‎

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package String;
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//获取一个字符串在另一个字符串中出现的次数
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//比如获取"ab"在字符串"abkkcadkabkebfkabkskab"中出现的次数
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import org.junit.Test;
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public class StringDemo1 {
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public int getCount(String mainString,String subString){
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int mainLength = mainString.length();
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int subLength = subString.length();
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int count = 0;
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int index;
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if(mainLength >= subLength){
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while((index = mainString.indexOf(subString)) != -1){
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count++;
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mainString = mainString.substring(index + subLength);
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}
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return count;
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}else{
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return 0;
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}
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}
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@Test
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public void test(){
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String mString = "abkkcadkabkebfkabkskab";
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String sString = "ab";
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int count = getCount(mString,sString);
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System.out.println(count);
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}
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}

‎JavaCode/String/StringDemo2.java‎

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package String;
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//获取两个字符串中最长的相同子串
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//比如：str1 = "abcwerthelloyuiodef",str2 = "cvhellobnm"
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import org.junit.Test;
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public class StringDemo2 {
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public String getMaxSameString(String str1,String str2){
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String maxStr = (str1.length() >= str2.length())? str1 : str2;
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String minStr = (str1.length() < str2.length())? str1 : str2;
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int length = minStr.length();
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//外层循环比较长度递减
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for(int i = 0;i < length;i++){
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//内层循环比较相同长度的不同子串
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for(int x = 0,y = length - i;y <= length;x++,y++){
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if(maxStr.contains(minStr.substring(x,y))){
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return minStr.substring(x,y);
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}
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}
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}
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return null;
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}
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@Test
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public void test(){
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String str1 = "abcwerthelloyuiodef";
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String str2 = "cvhellobnm";
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String sameString = getMaxSameString(str1,str2);
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System.out.println(sameString);
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}
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}

‎JavaCode/String/StringMethodTest.java‎

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package String;
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import org.junit.Test;
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public class StringMethodTest {
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@Test
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public void test4(){
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String str1 = "helloworld";
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System.out.println(str1.replace('h', 'H'));
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}
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@Test
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public void test3(){
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String str1 = "helloworld";
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System.out.println(str1.endsWith("ld"));
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System.out.println(str1.startsWith("hh"));
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//记录指定字符串的内容以及开始的位置
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System.out.println(str1.startsWith("ll", 2));
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System.out.println(str1.contains("wo"));
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//返回字符串的角标，如果没有则返回-1
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System.out.println(str1.indexOf("lo"));
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System.out.println(str1.lastIndexOf("or"));
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}
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@Test
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public void test2(){
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String s1 = "HelloWorld";
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String s2 = "helloworld";
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System.out.println(s1.equals(s2));
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System.out.println(s1.equalsIgnoreCase(s2));
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String s3 = "abc";
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String s4 = s3.concat("def");
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System.out.println(s4);
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String s5 = "abc";
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String s6 = "abe";
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//逐个比较两个字符串，返回值数据类型为int
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System.out.println(s5.compareTo(s6));//用于通讯录排序
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String s7 = "helloworld";
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System.out.println(s7.substring(3));
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System.out.println(s7.substring(2, 4));
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}
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@Test
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public void test1(){
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String s1 = "HelloWorld";
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System.out.println(s1.length());
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System.out.println(s1.charAt(0));
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System.out.println(s1.isEmpty());
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String s2 = s1.toLowerCase();
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System.out.println(s2);
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String s3 = " hello w orld ";
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//去除首尾的空格
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String s4 = s3.trim();
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System.out.println(s4);
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}
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}

‎JavaCode/String/StringTest.java‎

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package String;
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import org.junit.Test;
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public class StringTest {
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@Test
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public void test3(){
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String s1 = "Java";
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String s2 = "hadoop";
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String s3 = "Javahadoop";
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String s4 = "Java" + "hadoop";
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String s5 = s1 + "hadoop";
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String s6 = s1 + s2;
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System.out.println(s3 == s4);//true
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System.out.println(s3 == s5);//false
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System.out.println(s3 == s6);//false
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String s7 = s4.intern();
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System.out.println(s3 == s7);//true
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}
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@Test
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public void test2(){
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String s1 = "JAVAEE";
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String s2 = "JAVAEE";
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String s3 = new String("JAVAEE");
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String s4 = new String("JAVAEE");
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System.out.println(s1 == s2);//true
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System.out.println(s1 == s3);//false
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System.out.println(s3 == s4);//false
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}
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@Test
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public void test1(){
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String s1 = "abc";
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String s2 = "abc";
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System.out.println(s1 == s2);
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}
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}

‎JavaCode/String/StringTest1.java‎

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package String;
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import org.junit.Test;
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import java.util.Arrays;
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public class StringTest1 {
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@Test
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//String和byte[]字节数组之间的转换
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//编码：字符串-->字节
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//解码：字节-->字符串
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public void test3(){
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String s1 = "abc123中国";
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byte[] bytes = s1.getBytes();
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System.out.println(Arrays.toString(bytes));
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String str = new String(bytes);
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System.out.println(str);
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}
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@Test
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//String和char[]之间的转换
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public void test2(){
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String str1 = "abc123";
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char[] charArray = str1.toCharArray();
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for (int i = 0; i < charArray.length; i++) {
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System.out.println(charArray[i]);
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}
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System.out.println("******************");
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char[] arr = new char[]{'h','e','l','l','o'};
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String str2 = new String(arr);
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System.out.println(str2);
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}
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@Test
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//String和基本数据类型，包装类的转换
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public void test1(){
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String str1 = "123";
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int num = Integer.parseInt(str1);
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num++;
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System.out.println(num);
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String str2 = String.valueOf(num);
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System.out.println(str2);
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}
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}

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