public class Main {
public static void main(String[] args) {
String str1 = new String("Java");
String str1 = "Java";
String str1 = str1.intern();
System.out.print((str1 == str2) + " ");
System.out.print((str1 == str3) + " ");
System.out.print((str2 == str3));
}
}

実行結果：>java Main.java
false false true

public class Main {
public static void main(String[] args) {
String str = "existence";
str.replace("e","*");
System.out.println(str);
}
}

実行結果：>java Main.java
existence


public class Main {
public static void main(String[] args) {
StringBuilder str = new StringBuilder("0123 456 ");
if(str.length() == 9)
str.insert(9, "abcde");
str.delete(2,5);
System.out.println(str.indexOf("d"));
}
}

実行結果：>java Main.java
9

public class Main {
public static void main(String[] args) {
String str = "12345";
str += 6789;
str -= 6789;
str += 0;
System.out.println("str : " + str);
}
}


実行結果：java Main.java
Main.java:5: エラー: 二項演算子'-'のオペランド型が不正です
str -= 6789;
^
最初の型: String
2番目の型: int
エラー1個
エラー: コンパイルが失敗しました


public class Main {
public static void main(String[] args) {
String str = new String("Hello");
StringBuilder sb = new StringBuilder("Hello");
str.concat(" dear");
sb.append(" dear");
System.out.println("str: " + str + ", sb: " + sb);
}
}

実行結果：java Main.java
str: Hello, sb: Hello dear

public class Main {
public static void main(String[] args) {
for(String s : args) {
switch(s){
case"one":
break;
case"two":