a

build.gradle.kts

@@ -32,7 +32,7 @@ dependencies {
     testImplementation(platform("org.junit:junit-bom:5.10.0"))
     testImplementation("org.junit.jupiter:junit-jupiter")
     testRuntimeOnly("org.junit.platform:junit-platform-launcher")
-    implementation("org.checkerframework:checker-qual:3.43.0")
+    implementation("org.slf4j:slf4j-api:2.0.17")
 }
 
 tasks.test {

gradle.properties

@@ -1,5 +1,5 @@
 GROUPSID=com.mingliqiye
-ARTIFACTID=socket-utilts
+ARTIFACTID=string-utilts
 VERSIONS=0.1
-MAINCLASS=com.mingliqiye.Main
+MAINCLASS=com.mingliqiye
 JDKVERSIONS=1.8

settings.gradle.kts

@@ -1 +1 @@
-rootProject.name = "socket-utilts"
+rootProject.name = "string-utilts"

src/main/java/com/mingliqiye/Main.java

@@ -1,13 +0,0 @@
-package com.mingliqiye;
-
-public class Main {
-    /**
-     * @param args []
-     */
-    public static void main(String[] args) {
-        System.out.print("Hello and welcome!");
-        for (int i = 1; i <= 5; i++) {
-            System.out.println("i = " + i);
-        }
-    }
-}

src/main/java/com/mingliqiye/utils/StringUtil.java

@@ -0,0 +1,67 @@
+package com.mingliqiye.utils;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.slf4j.helpers.MessageFormatter;
+
+public class StringUtil {
+
+    public static String toString(Object obj) {
+        return obj == null ? "" : obj.toString();
+    }
+
+    public static String format(String format, Object... args) {
+        return MessageFormatter.arrayFormat(format, args).getMessage();
+    }
+
+    public static boolean isEmpty(String str) {
+        return str == null || str.isEmpty();
+    }
+
+
+    public static String joinOf(String spec, String... objects) {
+        return join(spec, Arrays.asList(objects));
+    }
+
+
+    public static List<String> split(String str, String separator) {
+        List<String> data =
+                new ArrayList<>(Arrays.asList(str.split(separator)));
+        while (!data.isEmpty() && data.getFirst().isEmpty()) {
+            data.removeFirst();
+        }
+        return data;
+    }
+
+    public static <P> String join(
+            String separator, List<P> list,
+            PRFunction<P, String> fun
+    ) {
+        StringBuilder sb = StringUtil.stringBuilder();
+        for (int i = 0; i < list.size(); i++) {
+            P item = list.get(i);
+            if (i == 0) {
+                sb.append(fun == null ? item.toString() : fun.call(item));
+            } else {
+                sb.append(separator)
+                        .append(fun == null ? item.toString() : fun.call(item));
+            }
+        }
+        return sb.toString();
+    }
+
+    public static String join(String separator, List<String> list) {
+        return join(separator, list, null);
+    }
+
+    public static StringBuilder stringBuilder() {
+        return new StringBuilder();
+    }
+
+    @FunctionalInterface
+    public interface PRFunction<P, R> {
+        R call(P p);
+    }
+}