Refactor Java API (#806)

sherpa-onnx/java-api/src/com/k2fsa/sherpa/onnx/OnlineLMConfig.java

@@ -1,16 +1,20 @@
-/*
- * // Copyright 2022-2023 by zhaoming
- */
+// Copyright 2022-2023 by zhaoming
+// Copyright 2024 Xiaomi Corporation
 
 package com.k2fsa.sherpa.onnx;
 
 public class OnlineLMConfig {
+
     private final String model;
     private final float scale;
 
-    public OnlineLMConfig(String model, float scale) {
-        this.model = model;
-        this.scale = scale;
+    private OnlineLMConfig(Builder builder) {
+        this.model = builder.model;
+        this.scale = builder.scale;
+    }
+
+    public static Builder builder() {
+        return new Builder();
     }
 
     public String getModel() {
@@ -20,4 +24,23 @@ public class OnlineLMConfig {
     public float getScale() {
         return scale;
     }
-}
+
+    public static class Builder {
+        private String model = "";
+        private float scale = 1.0f;
+
+        public OnlineLMConfig build() {
+            return new OnlineLMConfig(this);
+        }
+
+        public Builder setModel(String model) {
+            this.model = model;
+            return this;
+        }
+
+        public Builder setScale(float scale) {
+            this.scale = scale;
+            return this;
+        }
+    }
+}