accounts/abi/bind: generate java structs

This commit enables struct generation for contracts on java.
It will generate for the TUPLE contract the following:

// TupleP is an auto generated low-level Java binding around an user-defined struct.
	public class TupleP {
		public BigInt x;
		public BigInt y;
	}

	// TupleQ is an auto generated low-level Java binding around an user-defined struct.
	public class TupleQ {
		public BigInt x;
		public BigInt y;
	}

	// TupleS is an auto generated low-level Java binding around an user-defined struct.
	public class TupleS {
		public BigInt a;
		public BigInts b;
		public TupleT[] c;
	}

	// TupleT is an auto generated low-level Java binding around an user-defined struct.
	public class TupleT {
		public BigInt x;
		public BigInt y;
	}

	// Func1Results is the output of a call to func1.
	public class Func1Results {
		public TupleS Return0;
		public TupleT[][] Return1;
		public TupleT[][] Return2;
		public TupleS[] Return3;
		public BigInts Return4;
	}

accounts/abi/bind/bind.go

@@ -22,7 +22,6 @@ package bind
 
 import (
 	"bytes"
-	"errors"
 	"fmt"
 	"go/format"
 	"regexp"
@@ -165,10 +164,6 @@ func Bind(types []string, abis []string, bytecodes []string, fsigs []map[string]
 		if evmABI.HasReceive() {
 			receive = &tmplMethod{Original: evmABI.Receive}
 		}
-		// There is no easy way to pass arbitrary java objects to the Go side.
-		if len(structs) > 0 && lang == LangJava {
-			return "", errors.New("java binding for tuple arguments is not supported yet")
-		}
 
 		contracts[types[i]] = &tmplContract{
 			Type:        capitalise(types[i]),

accounts/abi/bind/bind_test.go

@@ -2150,7 +2150,7 @@ public class Test {
 			for _, line := range lines {
 				if strings.TrimSpace(line) != "" {
 					lines[index] = line
-					index += 1
+					index++
 				}
 			}
 			lines = lines[:index]
@@ -2163,3 +2163,14 @@ public class Test {
 		}
 	}
 }
+
+// Tests binding the bindTests succeeds (does not execute test cases, only checks binding errors)
+func TestGenerateBindingingJava(t *testing.T) {
+	// Generate the test suite for all the contracts
+	for _, tt := range bindTests {
+		_, err := Bind([]string{tt.name}, tt.abi, tt.bytecode, nil, "bindtest", LangJava, nil, tt.aliases)
+		if err != nil {
+			t.Fatalf("test %s: failed to generate binding: %v", tt.name, err)
+		}
+	}
+}

accounts/abi/bind/template.go

@@ -613,6 +613,14 @@ import java.util.*;
 		this(Geth.bindContract(address, ABI, client));
 	}
 
+	{{range $structs}}
+	// {{capitalise .Name}} is an auto generated low-level Java binding around an user-defined struct.
+	public class {{capitalise .Name}} {
+		{{range $index, $item := .Fields}}public {{$item.Type}} {{if ne .Name ""}}{{.Name}}{{else}}Return{{$index}}{{end}};
+		{{end}}
+	}
+	{{end}}
+
 	{{range .Calls}}
 	{{if gt (len .Normalized.Outputs) 1}}
 	// {{capitalise .Normalized.Name}}Results is the output of a call to {{.Normalized.Name}}.